Model 520 - Lake Shore Cryotronics, Inc.
Contents
1. I Perform all repairs at a static free work station J Only grounded tip soldering irons and anti static type de soldering devices should be used ole A troubleshooting guide for the 520 is given in Table 5 1 To properly use the guide complete the operational check given earlier in this section and note any discrepancies Locate the problem in the Symptom column and perform the appropriate tests for the possible causes as listed next to the Symptom Corrective actions are given for the various possible causes Schematics and component layouts for the various pcb assemblies are given later in this section The test equipment necessary for troubleshooting is as follows A Digital voltmeter multimeter 4 digits or more B Test cable and precision resistors to simulate the temperature sensors C Power resistor to simulate the heater Dul Replaceable Parts Below is a list of Tables and Figures for the 520 schematics replaceable parts list and illustrated components layouts Parts List Al Main PCB assembly Table 5 2 Component Layout AL Main PCB Figure 5 1 Schematic Al Main Schematics Figure 5 2 Schematic Al Output Section Figure 5 3 Schematic Al Power Supply Figure 5 4 Parts List A2 Front Panel Assembly Table 5 3 Parts List A3 Rear Panel Assembly Table 5 4 Parts List A4 Transformer Assembly Table 5 5 Parts List 5 Heater Current Heat Table 5 6 Sink Assembly Parts List SAli Heater Current Range T2. User s Manual Model 520 Cryogenic Temperature Indicator Controller Obsolete Notice This manual describes an obsolete Lake Shore product This manual is a copy from our archives and may not exactly match your instrument Lake Shore assumes no responsibility for this manual matching your exact hardware revision or operational procedures Lake Shore is not responsible for any repairs made to the instrument based on information from this manual LakeShore Lake Shore Cryotronics Inc 575 McCorkle Blvd Westerville Ohio 43082 8888 USA E Mail Addresses sales Qlakeshore com service lakeshore com Visit Our Website www lakeshore com Fax 614 891 1392 Telephone 614 891 2243 Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics Inc No government or other contractual support or relationship whatsoever has existed which in any way affects or mitigates proprietary rights of Lake Shore Cryotronics Inc in these developments Methods and apparatus disclosed herein may be subject to U S Patents existing or applied for Lake Shore Cryotronics Inc reserves the right to add improve modify or withdraw functions design modifications or products at any time without notice Lake Shore shall not be liable for errors contained herein or for incidental or consequential damages in connection with furnishing performance or use of this material Obsolete Manual
3. of full output can be set from front panel Manual and Automatic modes can be used simultaneously Heater Output 0 25 watts into 25 ohm load or 0 10 watts into 10 ohm load rear panel switch selected Heater current can be limited at 10mA 30mA 100mA 300mA and IA approximate decade power increments Temperature Readout Method Sensor voltage is nulled against set point equivalent voltage using front panel thumbwheels in MANual mode Temperature is deter mined from V T or R T tables requires sensor calibrated over approp riate temperature range Accuracy 100 microvolts calibration error of Sensor General Dimensions Weight 432mm wide x l46mm high x 330mm deep 17 in x 5 3 4 in x 13 in Style L full rack package Net weight 8 kg 18 lbs Power 105 125 or 210 250 VAC switch selected 50 or 60 Hz 50 watts 1 4 Major Assemblies Supplied The Model 520 Cryogenic Temperature Thermometer Controller includes as standard equipment in addition to the controller proper the following additional components A One Operating and Service Manual B One l4 pin male connector LSCI Stock 7106 070 and 12 pins 8 required LSCI Stock 7106 060 Assembly mates with Jl connector on Model 520 Rear Panel 1 5 Options and Accessories Available Model 5201 Interface Allows remote digital control of set point and provides BCD output of Sensor voltage divided by two Model SW 10A 10 Sensor Selector Switch Pushbutton s
4. 014 103 012 103 030 103 010 103 029 103 008 103 280 103 322 103 370 103 407 103 441 103 465 103 106 103 414 103 107 103 107 103 107 WO2M WO2M WO2M MR501 MR501 IN459A IN459A IN459A IN459A IN4749A IN750A IN4148 IN4148 601 30 020B 1 380991 0 307 050 520 202 3006P 1 105 3006P 1 504 3006P 1 104 3006P 1 503 3006P 1 103 _3006P 1 502 3006P 1 102 3006P 1 501 H ODER BO MO LS Ka Ka DO Ka BO do Ka Ka Ka Ka Ka Ka oa B S 37 Table 5 2 cont d ITEM LSCI TOT NO DESCRIPTION STOCK NO MFR PART NO QTY 38 R24 R25 R26 R27 R28 R29 R31 R32 R33 R34 R35 R36 R37 R38 R39 RAO RAI R42 R43 R44 R45 R46 R47 R48 R49 R50 R51 R52 R53 R54 R55 R56 R57 R58 R59 R60 R61 R62 R63 R64 R65 R66 R68 R69 R70 R71 RES MTF 10K 1 4W POT 10K RES MTF 10K 12 hW POT 10K RES MTF 1M 1 W RES MTF 12 1K 1 MW RES MTF 365 1 ZW RES MTIF 1969 12 4W RES MIF 10K 1 M RES MTF 9 76K 1Z kW POT 5009 RES MTF 4 99K 12 W RES VISHAY 100K 017 POT 100K POT LOOK RES MTF 301K 17 W RES MTF 301K 1 XM RES MTF 3 92K 1 ZW RES MTF 1L74K 1 1 4 RES MTF 10K 1 W RES MIF 174K 14 1 RES MTF 4 75K 17 HW RES MTF 4 75K 12 HW RES MTF 1K 1 W RES MTF LOOK 1 ZW RES MTF 4990 1 5 ZW RES MTF 9769 1 XW POT 502 RES MTF LOK 1 9 RES MTF 4 99K 1 LW RES MTF 10K 1 EW
5. 101 009 ECE A 1VV 4718 160 68J100G ECE A 1VV 4715 160 68J100G 160 68J100G ECE A 1VV 4718 160 68J100G 160 68J100G ECE A ICV 2228 160 68J100G 3186BA402U050BMA2 160 1K100G WMF1533 CD15CD151G03 WMF1D15 WMF1533 WMF1533 WMF1533 WMF1533 1501K100FG 1501K100FC 416P 10391 146P 10391 1501K100FC WMF 1533 WMF 1533 WMF1533 WMF1533 WMF1533 WMF1533 160 1K100G WMF1533 WMF1533 1501K100FC 160 1K100G 150 68J100FC 160 1K100G 160 68J100G Table 5 2 cont d ITEM LSCI TOT BRIDGE RECTIFIER BRIDGE RECTIFIER BRIDGE RECTIFIER DIODE RECTIFIER DIODE RECTIFIER DIODE SIL G P DIODE SIL G P DIODE SIL G P DIODE SIL G P DIODE ZENER 24V DIODE ZENER 4 7V DIODE SIL SIG DIODE SIL SIG HEAT SINK 1 4 4 METAL SCREW 4 40 KEP NUT 10 PIN TRANS CONNECTOR 50 PIN CONNECTOR RES MTF 2610 12Z 12W RES MIF 6 65K 1 4W RES MTF 3 74K 1 I4W POT IM POT 500K POT 100K POT POT POT POT POT RES MTF 2 15K 1 EW RES MTF 6 49K 17 XM RES MTF 21 5K 1Z2 4W RES MTF 64 9K 1Z2 iW RES MIF 215K 1Z LW RES MTF 649K 1 1zW RES MTF 2M 19 LU RES MTIF 82 5K 17 LU RES MTF 2 2M 1 EW RES MTF 2 2M 1 HW RES MIF 2 2M 1 14W 102 029 102 029 102 029 102 008 102 008 102 003 102 003 102 003 102 003 102 033 102 036 102 004 102 004 110 021 110 112 110 108 110 102 110 122 110 129 106 135 106 133 103 230 103 324 103 296 103 013 103 031 103
6. 4 0 380 1 7 Repacking for Shipment If the 520 appears to be operating incorrectly please discuss the problem with a factory representative before returning the instru ment He may be able to suggest several field tests which could avoid the unnecessary returning of a satisfactory instrument to the factory when the malfunction is elsewhere If these tests determine that the fault is in the instrument the representative will provide shipping and labeling instructions for returning it In order to expedite the repair of the instrument contact the factory for a Returned Goods Authorization RGA number Include the instrument s model and serial numbers in all written correspondence When returning an instrument please attach a tag securely to the instrument itself not on the shipping carton clearly stating A Owner and Address B Instrument Model and Serial Numbers C Malfunction Symptoms D Description of External Connections and Cryostats E Returned Goods Authorization Number If the original carton is available repack the instrument in a plastic bag place it in the carton using original spacers to protect protruding controls Seal the carton with strong paper or nylon tape Affix shipping labels and FRAGILE warnings If the original carton is not available pack the instrument similar to the above procedure being careful to use spacers or suit able packing material on all sides of the instrument This Page Intentionall
7. DAC If the input codes are wrong replace set point switch Instrument doesn t null properly cont d Input problem Verify that the output of the input buffer DIODE or amplifier RESISTOR is correct For diode input check if input voltage is present at pin 5 of Ul3 If it is not check for improper input connection If it is check to see if it is also at pin 10 of Ul3 and its negative value at pin 10 of Ul4 If it is not at one of these outputs replace that amplifier For resistor input check to see if the input voltage is present at pin 1 of Ull If it is not check for improper input connection If it is correct check to see the output pin 9 is equal to 100 times the input If it is not replace Ull Summing problem Verify that the output pin 10 of Ul9 is approximately zero when input voltage is equal to set point voltage If it is not replace Ul9 4 No heater current 7 Blown fuse Replace fuse two Output stage problem Set control mode to MANual and rotate the manual heater potentiometer on the front panel Verify that the voltage at pin 1 of U23 ranges from 0 to approximately 2 8V If this is in correct replace U23 Then check if the voltage across R99 varies between 0 and 1 volt If it doesn t try replacing U23 and or U25 If everything is correct to this point try replacing U23 and or U26 2 5e ka
8. Div 1 800 3 270 10 80 30 27 100 8 500 Zel 1000 0 8 F Automatic Reset Circuit Bounding Circuit The bound circuit and variable gain integrator are realized by operational amplifiers U21 and 022 respectively Note that for an under temperature con dition the voltage applied to these amplifiers is positive and the integrator will integrate unless the input voltage exceeds approximately 2 volts Above this voltage input the comparator output goes negative to close to 8 volts and diode CR14 conducts and causes the integrator to shut down effectively taking it out of the control circuit For an over temperature condi tion the input voltage is negative and the integrator output is clamped by the germanium diode CR15 to approximately 0 4 volts However with the input signal between zero and two volts the integrator is operational and ultimately once the system is controlling and stable the voltage developed across the integrating capacitor C36 becomes just equal to the error signal which would be required to hold the set point temperature under open loop conditions Since this voltage is now present on the capacitor of the reset amplifier it is no longer needed at the output of the gain summing amplifier resulting in the error signal reducing to zero The switch in series with R77 in the feedback loop is closed when the RESET control is in the off position and the amplifier gain is approximately 0 001 25 95 A
9. Q I gt 1 y LH r i G a a I x U ZOLU o gt fa 90Lu 2 cc GOLH o POLU o o k maj cold 4 HMd H31V3H OOLY gt lt t w e e N x cc x ST 8 gt oh 864 o i I tcc e a gt ve 96H gt 05 Lo ep 9 T jis LO o 205 gt 5 i w d v o e i N er ogy ese c c tc N O SER S nl 0 gt e c gt G T gt t 64 1334 A oo S O uu agu ESE o BL i 064 gt RESET 20 ye gt QT 15 P S 1 15R P S 2 P S 3 P S 4 P S 5 P S 6 c38 N 8 15 5 N3 C10 C9 C11 S7 P S 7 C12 SLLU Schematic Al Power Supply Figure 5 4 47 Table 5 3 Parts List A2 Front Panel Assembly SENSOR CURRENT SWITCH LED LED LED LED LED LED 6 32 x 3 8 STANDOFFS 6 32 KEP NUTS 6 32 NUTS 6 32 LOCK WASHERS NULL METER HEATER CURRENT METER MODEL 520 FRONT PANEL DWG PAINTED AND SILK SCREENED ARTWORK POWER SWITCH RES RES DIODE SELECTOR SWITCH HEATER CURRENT RANGE SWITCH ASSEMBLY LSCI Part 108 037 ITEM LSCI NO DESCRIPTION STOCK NO MFR PART NO 105 076 102 046 102 046 102 046 102 046 102 046 102 046 110 137 110 129 110 130 110 132 110 033 110 032 107 094 105 048 105 073 113 100 PA 1015 558 0101 003 558 0101 003 558 0101 003 558 01
10. R68 Increasing or decreas ing the sensor current by a factor of three would change the loop gain of the instrument by the same factor Therefore switch wafer S2D together with wafer switch SID adjust the amplifier gain by shorting out resistor R60 on the X3 X30 X300 and X3K scales so that the overall loop gain is not changed Since the Model 520 controller is capable of using both positive and negative temperature coefficient sensors a sign change must be made for the negative temperature coefficient sensors so that the control circuit will add power when the processed sensor voltage is greater than the set point voltage and reduce power when the inverse is true This is accomplished by means of the inversion amplifier U20 and the switch wafers S2F and S2G Null Meter Circuit The output of the variable gain amplifier is fed to the null meter circuit as well as the rest of the control circuits The Null Meter is desensitized for large errors by placing two germanium diodes across its terminals The result is a linear scale for errors less than 50Z of full deflection in either direction with a high non linearity for large errors The sensor set point error can be related to gain settings by the following table for small errors The units division are the set point units which are selected by the user Table 4 1 Translation of Null error versus set point deviation as a function of gain Gain Sensor Set Point Error S P Unit
11. Transfer Assembly Schematic Model 5201 BCD Option Parts List A5 Heater Current Heat Sink Assembly Page vi 10 14 11 14 20 19 25 41 34 43 36 45 49 47 50 57 51 39 51 Reference Table 5 7 Table 5 8 Table 5 9 Table 5 10 Table of Illustrations cont d Description Parts List SALL Heater Current Range Assembly Parts List A Final Assembly Parts List Model 5201 BCD Option PCB Assembly Cross Reference of Parts Manufacturers Page 52 33 54 61 V Vi ics Inc ER CRYOGENIC TEMPERATURE CONTROLL CURRENT rna SES rcns p RES a Yi ES DIO CONTROL MODE MIX AUTO Figure 1 1 Model 520 Cryogenic Temperature Controller SECTION I General Information Let Introduction This section contains a description of the Model 520 Thermo meter Controller its applications general specifications major assemblies supplied and accessory equipment available LZ Description and Applications The Model 520 Cryogenic Temperature Thermometer Controller is housed in an aluminum case and is rack mountable with the RM 5H rack mount kit in a standard 19 relay panel All connections are at the rear of the case with all normal operating controls on the front panel The instrument is line operated from either 115 volt or 230 volt mains 30 or 60 Hertz The controller has the performance features needed for use with Silicon or gallium arsenide diodes
12. available of one ampere The voltage supply for the current drive can be selected to have an output of 10 volts on a low setting or 25 volts on a high setting Figure 3 2 Key No 22 Page 14 therefore if your heater resistance is ten ohms or less the low resistance setting should be used so as to minimize power dissipation within the instrument The maximum power deliverable to the load is therefore equal to the load resistance as long as the resistance does not exceed 25 ohms for loads greater than 25 ohms the minimum power to the load is 25 R where R is your load resistance and it is assumed that the lead resistance to the heating element is negligible The Heating element should be floated to preclude the possibility of any of the heater current being coupled into the thermometer sensor leads Electrical feedback in addition to the desired thermal feedback may cause oscillations and certainly will cause erroneous temperature readings a Inspect the heater element fuse FU2 Figure 3 2 Key No 21 Page 14 for proper value 3AG 1 0A Fast Blow or smaller current rating if desired This fuse should not blow under most circumstances since the output stage is a current stage with an upper limit of one ampere rather than a voltage stage with maximum current depending on output resistance Table 2 1 Sensor Connections Jl Diode Pin Diode Assignments Diode Diode Resistor Resistor Resistor Resistor Figure 2 1 x F
13. germanium carbon glass platinum or other resistance thermometers or any sensor with a voltage response less than four volts or a resistance of less than 40 000 ohms The 520 is designed to accept a voltage signal or resistance equivalent signal from a temperature sensitive transducer compare this signal with an internal set point voltage or resistance equivalent voltage amplify and process their difference error signal and drive an external heating element Sensor currents from 1 microampere to 3 milliamperes can be selected from the front panel Use of analog control means constant and immediate correction for temperature changes Ample range of gain reset and rate have been designed into the 520 to assure fast response low offset error and high stability The Gain control of the Model 520 has 1X and 3X steps similar to those for the current supply As a result loop gain of the system can be kept constant even when sensor current must be changed to avoid sensor self heating or because of low signal value A heater output current of up to one ampere is available to drive up to a 25 ohm load Smaller load resistances will reduce the maximum power below 25 watts as will higher resistance loads due to the voltage limiting of the power supply of the output stage The maximum heater current may be set from 10 mA to 1 ampere in 1X and 3X steps which enables output power to be varied in decade steps over five orders of magnitude Manual
14. gt ge 3 rN OY E R78 R87 R85 1 Figure 5 1 sm Tum TT a D xw c s Component Layout Al Main PCB R89 R74 le J2 J2 1 R4 R20 R21 R2 9 SIA JUN 5 15 PE de Dar R5 R18 R19 g 4 t gi 3 l I I R6 R17 7 i LC 0 I l R7 R16 1 6 G3 i I 1 4 t t R8 R15 5 E l U R9 R14 YA 3 4 i U 8 20 R10 R13 3 l I La i R11 R12 I 51 i D R27 8 R26 N R29 8 R34 R35 pae 15R R J10 e R POI D a S2E A 14 AN OUT 5 t 12 15 gt AG CI 13 d DIS 2T4 TO POWER SUPPLY EI ns oe 15 Y BD R38 i R4O R41 MSB C2 3 AA 123 1 BB 12 ci dM ill 3 I 4 3 R37 i R69 R70 c2 i HR Wi 19 5 R59 at XIS 2120 6 R68 CR13 Y 21 7 EE Zi 122 8 ap R71 cil I I 1 i R67 MZ l I i h lt R60 t I l R65 c e am ai l Ti i I 10 1 R61 lt R62QR63 R64 R66 ma C GAIN Ll VI 1 EN 1 3 Ho 130 ho C1 l l O O O O O U SER i 3 4 GAIN R72 ess Li ndi m STD A A a mM 112 6 ZL LT Pi 131 7 S LT Ree 4 ci m l I i R55 W CA i K A AAA cz I l E YNNN 8 G 17 al Hi 18 10 191 R53 I 19 11 16 R56 R57 E 10 12 Sal pr C1 a 3 13 LSB a Figure 5 2 i i i R47 R46 igure 5 Schematic Al Main Schematics i I b 5 L 43 45 ig ri 1 O U fist ET a tc E t
15. 0 TRANSFORMER 109 015 8088 Table 5 6 Parts List A5 Heater Current Heat Sink Assembly LSCI Part if 113 106 LSCI El DESCRIPTION STOCK NO MER MFR PART NO 110 034 HEAT SINK AV 60585 2 3 4 HEAT SINK INSULATORS 110 004 SHOULDER WASHERS 110 176 HEX SOCKET 4X40X3 8 110 152 4 40 NUTS 110 106 4 40 KEP NUT 110 108 IC LIN V REG 102 048 LM317T 102 044 IRF9532 FET P CH POWER Ky Table 5 7 Parts List SAll Heater Current Range Assembly LSCI Part 113 100 LSCI TOT DESCRIPTION is eae MFR PART NO ory SHORTING WIRE 1 5 LONG LSCI 2 SHORTING WIRE 1 5 LONG RES 1009 1 5 ZW 103 216 1 RES 30 19 1 W 103 209 1 RES 109 12 4W 103 206 1 RES 3 01Q 12 12W 103 122 1 RES 12 5 2 5W 103 120 1 RES 4220 1 4W 103 236 1 RES 54 90 12 3W 103 479 ji RES 16 90 12 3W 103 478 1 RES 4 970 1 3W 103 477 1 RES 1 640 1 3W 103 476 1 RES 490 1 3W 103 475 1 m 2 POLE 5 POS ROTARY PA 1013 SWITCH WITH CARRIAGE HOLDER CNLB 52 Table 5 8 Parts List A7 Final Assembly LSCI Part 1020 LSCI TOT M DESCRIPTION STOCK NO MFR PART NO QTY MODEL 520 MAIN BOARD ASSEMBLY FRONT PANEL ASSEMBLY REAR PANEL ASSEMBLY TRANSFORMER ASSEMBLY WIRING ASSEMBLIES DWG j ENCLOSURE 6 32 x 3 8 PHMS 6 32 x 3 8 FHMS 6 32 KEP NUTS KNOBS SINGLE KNOBS DOUBLE RIBB
16. 01 003 558 0101 003 558 0101 003 8423 E 25 100 0 100 E 25 0 1 DC MA DLA3A125V C9 P10637 49 Table 5 4 Parts List A3 Rear Panel Assembly LSCI Part if 108 038 LSCI E DESCRIPTION STOCK NO MER MFR PART NO m HEATER CURRENT DRIVER TRANSISTOR HEAT SINK ASSEMBLY MAIN FUSE FUSEHOLDER FUSE 90 125V 3 4A 210 250V 4 10A HEATER FUSE FUSEHOLDER FUSE STRAIN RELIEF 4X40Xi FHMS 4X40X3 8 PHMS 4 40 KEP NUTS PLASTIC BOARD GUIDES GRAY BINDING POST BLACK BINDING POST BLACK BINDING POST 14 PIN CONNECTOR amp TERMINALS MODEL 520 REAR PANEL DWG f ANODIZED AND SILK SCREENED ARTWORK f POT lOK 115 230 SELECTOR SWITCH 3 POLE 2 POS SLIDE SW LINE CORD STANDARD CEE 113 106 106 007 110 019 110 016 106 007 110 020 110 006 110 105 110 101 110 108 110 039 106 002 106 001 106 001 106 142 106 061 107 095 103 038 105 014 105 072 112 021 112 019 342004A MDL 3 4A MDL 4 10A 342004A MDL 1A 939 37N1643 111 0113 001 111 0103 001 111 0103 001 206043 1 66399 3 CM38800 10K 46206LFR 50209L 17239 17740C Table 5 5 Parts List A4 Transformer Assembly LSCI Part 113 097 TOT CONTACTS FEMALE 106 058 60617 1 STANDOFFS 110 169 8 X 32 X 2 3 4 SCREWS 110 170 FHMS 8 32 NUTS 110 144 8 LOCK WASHERS 110 171 MOUNTING BRACKET 107 072 B239 82 01 A SHOULDER WASHERS 110 161 54008 CONNECTOR FEMALE 10 PIN 106 134 1 480285
17. 51 104 037 104 045 104 045 104 045 104 045 104 045 104 033 104 033 _ 104 033 104 033 160 1K100G 160 68J100G CD15CD391G03 160 68J100G 22 10 100 DB WMF1833 160 68J100G 160 68J100G 160 68J100G 150D155X9010A2 CD15CD331G03 IN743A IN743A 3432 2003 RES MTF 6492 12 2W 103 247 RES MTF 19612 1 4W 103 225 POT LOOK 103 014 3006P 1 104 RES MTF 5629 1 4W 103 242 ICL71CO3ACPI ICL8052ACPD 74123 74LS175 74LS175 74LS175 74LS175 7415175 7404 7404 7404 7404 Table 5 9 cont d LSCI El DESCRIPTION STOCK NO MFR PART NO Ed IC AND OR SELECT IC AND OR SELECT IC AND OR SELECT IC AND OR SELECT IC AND OR SELECT IC TIMER SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC SOCKET IC 104 020 104 020 104 020 104 020 104 020 104 028 106 111 106 106 106 105 106 105 106 105 106 105 106 105 106 105 106 106 106 106 106 106 106 106 106 105 106 105 106 105 106 105 106 105 106 107 CD4019BCN CD4019BCN CD4019BCN CD4019BCN CD4010BCN 1355 703 4028 514 AGIID 516 AGIID 516 AGIID 516 AGIID 516 AGIID 516 AGIID 516 AGIID 514 AGIID 514 AGIID 514 AGIID 514 AGIID 516 AGIID 516 AGIID 216 AGIID 216 AGIID 516 AGIID 508 AGTID 55 56 This Page Intentionally Left Bl
18. 9 02 20 04 21 04 ZZ 02 23 08 24 01 25 I 26 8 27 2 28 4 29 4 30 2 31 8 32 l Note BCD output is one half of actual sensor voltage 20 SECTION IV Theory of Operation 4 1 Introduction This section contains the theory of operation of the Model 520 Cryogenic Temperature Thermometer Controller In some applications it may be required for an experienced user to modify the gain reset or rate range The information given within this section should make these modifications straightforward 4 2 General Description Refer to Figures 5 1 5 2 5 3 and 5 4 as an aid in the following discussion A precision current source causes a DC current to bias the control sensor For a diode sensor the recommended current is 10 microamperes For a resistance thermometer the current choices range from 1 to 3000 microamperes in 1X and 3X steps The current chosen is a compromise between increasing the current to maximize signal size and keeping the signal small so that self heating of the thermometer does not give erroneous temperature data Therefore to keep the self heating to a minimum a voltage signal between l and 3 millivolts will give the best results For example a Germanium at 30 Kelvin will have a self heating error of 6 or 7 mK with a 10 mV excitation If this type of temperature rise or error is not a prob lem within the system then the larger signal strength should be used because of the improved signal to noise ratio Whi
19. A Table 5 2 Parts List Al Main Schematics LSCI Part 113 096 r Tor Am DESCRIPTION stock wo MER MFR PART NO 30 MODEL 520 MAIN BOARD P C BOARD ARTWORK ff D278 83 01B SHORTING BOARD CAP ELECT 470MF 35V CAP POLY 68MF 100V CAP ELECT 470MF 35V CAP POLY 68MF 100V CAP POLY 68MF 100V CAP ELECT 470MF 35V CAP POLY 68MF 100V CAP POLY 68MF 100V CAP ELECT 2200MF CAP POLY 68MF 100V CAP ELECT 4000MF CAP POLY 0 1MF 100V CAP MYLAR 033MF 100V CAP MICA 150PF 500V CAMp MYLAR 0015MF 100V CAP MYLAR 033MF 100V CAP MYLAR 033MF 100V CAP MYLAR 033MF 100V CAP MYLAR 033 7 100V CAP POLY 1MF 100V CAP POLY 1MF 100V CAP MYLAR 01 100V CAP MYLAR 01 100V CAP POLY IMF 100V CAP MYLAR 033MF 100V CAP MYLAR 033MF 100V CAP MYLAR 033MF 100V CAP MYLAR 033MF 100V CAP MYLAR 033MF LOOV CAP MYLAR 033MF 100V CAP POLY 1MF 100V CAP MYLAR 033MF 100V CAP MYLAR 033MF 100V CAP POLY IMF 100V CAP POLY 0 1MF 100V CAP POLY 68MF 100V CAP POLY 0 1MF 100V CAP POLY 68MF 100V 111 036 111 030 101 001 101 009 101 001 101 009 101 009 101 001 101 009 101 009 101 057 101 009 101 056 101 008 101 005 101 013 101 004 101 005 101 005 101 005 101 005 101 011 101 011 101 020 101 020 101 011 101 005 101 005 101 005 101 005 101 005 101 005 101 008 101 005 101 005 101 011 101 008 101 010 101 008
20. ET circuit integrating the steady error The heater current meter will gradually rise toward full scale deflection The rate at which the heater current rises is determined by the RESET time constant setting The rate is a minimum in the counterclockwise position and a maximum in the fully clockwise position Abruptly change the set point voltage to cause 10 units deflection of the NULL meter to the left The HEATER CURRENT meter should gradually decrease from full scale deflection to zero The rate at which the current meter goes to zero is in part determined by the reset bounding circuit Similar tests should be performed for the Res and Res modes If the instrument does not respond to the tests as outlined refer to Section 5 6 for the Troubleshooting procedure Dio Calibration The test equipment necessary for calibration is as follows A Digital voltmeter multimeter 4 digits or more B Test cable and precision resistors to simulate the temperature sensors C Precision voltage source Refer to Figure 5 1 Component Layout Al Main PCB for adjust ment trimpot locations BASIE Current Sources The eight independent sensor current values have been factory calibrated to better than 01 of value To check the sensor current a precision resistance of not less than 01 tolerance should be connected across the I and I leads for one of the two sensor type inputs Jl pins l and 7 for diode or pins 8 and 14 for resisto
21. INST AMP IC LIN OP AMP IC LIN OP AMP lC LIN OP AMP IC DAC IC DAC IC LIN OP AMP IC LIN OP AMP IC LIN OP AMP a rj Aj p KA Ka An 40 IC LIN OP AMP lC LIN DUAL OP AMP IC LIN OP AMP IC DUAL OP AMP IC DUAL OP AMP FET N CH PWR SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET SOCKET IC DIP 8 PIN IC DIP l6 PIN DIP 8 PIN DIP 14 PIN IC IC IC 1G IC IC IC IC IC IC IC IC IC DIP DIP DIP DIP DIP DIP DIP DIP DIP DIP DIP 14 PIN 24 PIN 24 PIN 14 PIN 14 PIN 14 PIN 8 PIN 8 PIN 14 PIN 8 PIN 8 PIN 104 001 104 084 104 050 104 007 104 007 102 045 106 107 106 105 106 107 106 106 106 106 106 103 106 103 106 106 106 106 106 106 106 107 106 107 106 106 106 107 106 107 OPO EP LM353N ICL7650CPD MC1458PI MC1458PT VNO106N5 508 AGIID 516 AGIID 508 AGIID 514 AGIID 514 AGIID 524 AGI ID 524 AGI ID 514 AGI ID 514 AGI ID 514 AGIID 508 AGI ID 508 AGI ID 514 AGI ID 508 AGLID 508 AGIID R80 L CR 14 X U21 R88 R86 ji J1 d R84 R77 R90 SL IF pimi z 5 5 5 TERRE X U11 pates je up Ja Hi AL aadal pages o ee u a X U17 R68 R69 R66 X U13 R60 R64 s 2 3 OI I o BOGE A X om T TTS y BL w i 5
22. Inc HTR CURRENT RANGE MICROAMPERES CRYOGENIC TEMPERATURE CONTROLLER MILLIAMPERES E w MODEL 520 3 RES 1 BELOW NULL ABOVE HEATER CURRENT SENSOR VOLTAGE GAIN CONTROL MODE NEM k MIX AUTO SET POINT SENSOR VOLTAGE na OHMS seen POWER ALERT VOLTS 40 400 4K 40K e e e e e e 13333 MAX FOR X3 SENSOR CURRENTS MIN OFF MAX MIN OFF MAX y d p c SEZ FRZ SER EAR GO 5 n H MIN HEATER CURRENT x VARIABLE D OU ww uw Figure 3 1 Model 520 Cryogenic Temperature Controller Front Panel 2 amp amp o HH o HEATER 230 115 VAC 475A SB f amp HIGH LOW RESISTANCE gt TORT id N m E TR eli a e em E R O Ba l Figure 3 2 Model 520 Cryogenic Temperature Controller Rear Panel 14 3 3 Initial Checks Initial checks calibration checks and servicing procedures are described in Section V MAINTENANCE 3 4 Temperature Readout Mode To use the 520 as a cryogenic thermometer to measure the temperature of a calibrated sensor initially position the switches and controls as follows Sensor selector switch Key No 14 to type of sensor HTR CURRENT RANGE Key No 12 to 10 HEATER CURRENT Potentiometer Key No 8 to MIN CONTROL MODE switch Key No 7 to MAN GAIN Key Nos 5 and 6 to minimum setting RESET Key No 9 to off RATE Key No 10 to off POWER switch Key No 11 to on GD G j b UC CO UJ gt The null meter will probab
23. K 1 HW RES MTF 100K 12 W RES MTF 1 96M 1 ZW RES MTF 1009 1 4W RES MTF 1K 1 W RES MTF LOK 1 4W RES MIF 49 9K 1 EW RES MTF LOOK 1 35W RES MTF 100K 14 l RES MTF LOK 14 MW RES MTF 49 9K 1 MW RES MTF 5620 1 1 4 RES MTF 2002 1 5 ZW RES MTF LOK 1 5 ZW RES MTF 2 1 5 ZW RES MTF 49 9K 12 kW RES MTF 10K 1 W RES MIF 3322 1 W SWITCH AND POT ASSEMBLY SWITCH POTENTIOMETER 49719 SKPCB 1 CM44307 10K SWITCH AND POT ASSEMBLY SWITCH POTENTIOMETER 49734 SKPCB 1 CM44307 10K SWITCH AND POT ASSEMBLY SWITCH POTENTIOMETER HOLDER CM43318 100K DH 2 SWITCH AND POT ASSEMBLY SWITCH POTENTIOMETER HOLDER CM43318 100K DH 2 39 Table 5 2 cont d ITEM LSCI TOT NO DESCRIPTION STOCK NO MFR PART NO QTY SET POINT SWITCH ASSEMBLY 105 031 105 032 2A216056G 3A216056G 102 025 102 025 102 034 102 028 102 027 102 022 102 011 LM399H 104 013 LM308N 102 020 3N163 104 083 AD524CD 104 001 OPO7EP 104 050 ICL7650CPD 104 050 ICL7650CPD 104 085 DAC80 CCD V 104 085 DAC80 CCD V 104 050 IGL 650CPD 104 050 ICL7650CPD 104 050 ICL7650CPD MC7815CT MC7815CT MC7808CT MC7915CT MC7908CT MC7805CT 15V REGULATOR 15V REGULATOR 8V REGULATOR 15V REGULATOR 8V REGULATOR 5V REGULATOR VOLTAGE REFERENCE IC LIN OP AMP FET P CH IC LIN
24. ON CABLE HOLDERS 520 IC KIT Jl MATE CONNECTOR AND TERMINALS 113 096 108 037 108 038 113 097 112 032 108 004 110 121 110 127 110 129 105 054 105 055 110 167 113 091 106 070 106 060 SS 70TS2 2BIK SS 50L 70CTSL CFCC 8 206044 1 206070 1 53 Table 5 9 Parts List Model 5201 BCD Option PCB Assembly LSCI Part 1000 031 ITEM I LSCI TOT 111 039 Model 520 BCD Option 54 P C Board Artwork C274 83 01 CAP POLY 0 1MF 100V CAP POLY 68MF 100V CAP MICA 390PF 500V CAP POLY 68MF 100V CAP POLY 22MF 100V CAP MYLAR 033MF 100V CAP POLY 68MF 100V CAP POLY 68MF 100V CAP POLY 68MF 100V CAP TANT 1 5MF 10V CAP MICA 330PF 500V DIODE DIODE 40 PIN HEADER RES MTF 100K 17 3 RES MTF 100K 1 W RES MTF 3012 1 4W RES MTF 36 5K 14 5 KW RES MTF 200K 1 4W RES MIF 1 96M 1 W RES MIF 33 2K 1 W IC A D CONVERTER IC A D SUPPORT CHIP IC DUAL ONE SHOT IC 4 BIT LATCH IC 4 BIT LATCH IC 4 BIT LATCH IC 4 BIT LATCH IC 4 BIT LATCH IC INVERTER IC INVERTER IC INVERTER IC INVERTER 101 008 101 009 101 016 101 009 101 050 101 005 101 009 101 009 101 009 101 007 101 015 102 002 102 002 106 049 103 420 103 420 103 448 103 384 103 439 103 106 RES MIF 866 15 WN 103 250 103 381 104 059 104 0
25. October 1983 ii Section Table of Contents Es General Information Ka Ka Ka KO ps JOU POCO KM Introduction Description and Applications General Specifications Major Assemblies Supplied Options and Accessories Available Temperature Sensors Repacking for Shipment LE Introduction Mm ND NN OO ND U UN FEN FS DD NN NKL N IS UNE PEN Introduction Initial Inspection Power Requirements Grounding Requirements Instrument Grounding Temperature Sensor Grounding Instrument Installation Bench Use Rack Mounting Sensor and Heater Connections Sensor Input Connections Heater Connections Lil Operating Instructions 0 DH Co Co WH Co W COON DU WH P Introduction Controls Indicators and Connectors Initial Checks Temperature Readout Mode Constant Temperature Control Mode MAN and MIX Control Mode Remote Parallel BCD Input Output Option Grounding IV Theory of Operation 4 1 4 2 4 3 Introduction General Description Detailed Description Page U P ON RP KO 00 00 00 00 CO CO CO CO NJ 11 11 15 15 16 17 18 18 a 21 22 Section V Un Un Y Ui Un Un Cn Ui uu Un Un Ui Co W Un Un UT in Un Ui Ui GA Table of Contents cont d Maintenance and Calibration KA JOU E lo N UT PN W Dot Introduction General Maintenance Access Information Fuse Replacement Model 5201 BCD Option Installation Operational Checks Cali
26. RES MTF 28 7K 1 HW POT 5K RES VISHAY 100K 017 RES MIF 33 2K 1 W RES MTF 64 9K 1 4W RES MTF 3 24K 1 W RES MTF 1K 1 M RES MTF 3320 14 MW RES MTF 1009 17 HW RES MIF 10K 1 4W RES MTF 1K 1 2 W RES MTF 1002 17 ZW RES MTF 1K 17 MW RES MTF 1 18K 1 ZW RES MIF lK 1Z W 103 358 103 030 103 358 103 030 103 472 103 360 103 233 103 225 103 358 103 355 103 008 103 308 103 017 103 005 103 005 103 448 103 448 103 298 103 435 103 358 103 435 103 306 103 306 103 491 103 492 103 251 103 262 103 033 103 358 103 308 103 358 103 376 103 010 103 017 103 381 103 407 103 291 103 265 103 232 103 216 103 358 103 265 103 216 103 265 103 267 103 265 3006P 1 103 3006P 1 103 3006P 1 501 S102C 3059Y 1 104 3059Y 1 104 S102C1K0000 0 1 S102C100K00 0 1 3006P 1 500 3006P 1 502 s102C Table 5 2 cont d ITEM LSCI TOT DESCRIPTION STOCK NO wra MFR PART NO RES MTF 49 9K 12 MW 5 RES MTF 49 9K 1 4W RES MTF 1009 1 4W RES MTF 1 96M 17 XW RES MTF 1009 12 XW RES MTF LOOK 1 ZW RES MTF 4 99K 12 ZW RES MTF 2K 1 54W RES MTF LOOK 1 il RES MIF 1M 1 4 W RES MTF 100K 12 4W RES MTF 215K 1Z XW RES MTF 215
27. Series Sensors O to 4 volts for other diode sensors 0 40 ohms to 0 40K ohms for resistance sensors 4 ranges selected by Sensor Current selector Recommended Sensors DT 500 Series silicon or TG 100 Series gallium arsenide diode sensors CGR 1 carbon glass GR 200 germanium or PT 100 platinum resistance sensors Order sensors separately Calibration required over appropriate temperature range to provide V T or R T data Resistors with either positive or negative temperature coefficients can be utilized Sensor Input Separate diode and resistor inputs 4 terminal input for each type Can be connected in 2 wire configuration Sensor Excitation 1 3 10 30 100 300 1000 and 3000 microamperes resistors or 1 10 100 and 1000 microamperes diodes selected from the front panel Temperature Control Set Point Selected via 5 front panel digital thumbwheel switches from 00000 to 39999 Decimal point is automatically positioned de pending on sensor type and sensor current selected to indicate 0 0000 to 3 9999 volts 00 000 to 39 999 ohms 000 00 to 399 99 ohms 0000 0 to 3999 9 ohms or 00000 to 39999 ohms Optional BCD control with Interface Typical Controllability 0 0005K for temperatures below 30K 0 005K at higher temperatures with silicon diodes in a properly designed system Control Modes Automatic Proportional gain integral reset and derivative rate set from front panel controls Manual 0 to 100
28. The chassis is grounded by the 3 lead power cable to the electrical supply common ground The common lead of the controller circuitry LOW terminal of the heater output Key 23 Fig 3 2 can be externally con nected to the chassis ground terminal Although the grounding of the controller common is normal operation practice the common LOW terminal may be disconnected from chassis ground if doing so helps to eliminate accidental ground loops within the system PROGRAMMED SET POINT TEMP SAMPLE HOLDER TEMP NEW SET PT TEMP Pd 7 z Wu ir INSTANTANEOUS TEMP ERROR TEMP l TIME TIME OF ABRUPT CHANGE IN SET PT TEMP INITIAL PROGRAMMED SET POINT TEMP SET PT SAMPLE HOLDER TEMP TEMP INSTANTANEOUS TEMP ERROR NEW N SET PT Pam TEMP TIME TIME OF ABRUPT REDUCTION IN SET PT TEMP Figure 3 3 Temperature versus Time Characteristics of Controller 219 Parallel BCD Output of Sensor Voltage Input of Set Point 2 A 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 BCD VOLTAGE BCD VOLTAGE BCD VOLTAGE SET POINT BCD VOLTAGE SET POINT OUTPUT PIN INPUT PIN OUTPUT PIN INPUT 0008 33 l 34 2 l 0001 2 3 0002 4 0004 35 DATA VALID 36 l 5 0004 6 0002 37 38 If high 5V 7 0008 8 0001 39 Common BE Er PE PRES Codd Set Point S m daz 40 Common Ground 11 002 T2 004 13 004 14 002 15 008 16 001 17 Ol 18 08 1
29. able 5 7 Assembly Parts List Final Assembly Table 5 8 Parts List Model 5201 BCD Opton PCB Assembly Table 5 9 Component Layout Model 5201 BCD Option PCB Figure 5 5 Schematic Model 5201 BCD Option Figure 5 6 The parts lists include the following information A Reference Designation or Item Number B Description of each part C LSCI Stock Number D Abbreviated Manufacturer see end of section for Cross Reference of Parts Manufacturers Table 5 10 E Manufacturer Part Number or Type F Total Quantity per assembly or component De sd How to Obtain Parts Components may be ordered directly from the manufacturer by using the manufacturer s part number or from LSCI or authorized LSCI representative by using the LSCI part number To ensure proper handling of your order include the follow ing information 0 G O gt Quantitv LSCI Stock Number Description Reference designation or item number Assembly number Instrument model and serial number 33 A Table 5 1 Troubleshooting Guide for Model 520 Symptom Possible Cause Corrective Action General Failure 1 Blown fuse Replace fuse one 115 230 V line switch set to 230 V using a 115 V line Set switch to 115 V Power supply failure Verify the D C potential at the output of the power supply regulators Ul U7 with respect to their respective grounds If any of these regulators has no output then check to see if it ha
30. ank e U7 X US X U7 X U6 X US X U m X U1 4 TT 1 EH CR2 e cc A P1 Figure 5 5 Component Layout Model 5201 BCD Option PCB 57 f De elolajelo elo r 2 ola elolelo le 2s ejolelolele elal leleleizle que A fr TAT TATE IET TM p FETE ZI felolaje s jelolo FITTE v eH IL T sett GEH 4d gt gt steel ooi o EUR del Schematic Model 5201 BCD Option Fi ure 5 6 5 5 5 15 59 Table 5 10 Cross Reference of Parts Manufacturers AD Analog Devices BUS Bussman Div McGraw Edison Rt 1 Industrial Park P O Box 14460 P O Box 280 St Louis MO 63178 Norwood MA 02062 314 394 2877 617 329 4700 CDE Cornell Dubilier AMCO Ameo Electronics 150 Avenue L Div of G A W Electronics Newark NJ 07101 9181 Gazette Ave Chatsworth CA 91311 CENT Centralab Inc 213 882 9027 5855 N Glen Park Road P O Box 2032 AMP Amp Inc Milwaukee WI 53201 Harrisburg PA 17105 414 228 7380 717 564 0100 DLT Dialight Dialco AUG Augat Inc 203 Harrison Place 33 Perry Ave Brooklyn NY 11237 P O Box 779 212 497 7600 Attleboro MA 02703 617 222 2202 EDAC EDAC Inc 20 Railside Rd AV Aavid Engineering Inc Don Mills ON Canada M3A 1A4 30 Cook Court 416 445 2292 Box 400 Laconia NH 03247 EECO EECO Inc 603 524 4443 1601 E Chestnut Ave Santa Ana CA 92701 BB Burr Bro
31. bration Current Sources Set Point Diode Input Buffer Resistor Input Amplifier 3X Current Summing Troubleshooting Replaceable Parts How to Obtain Parts Page 2 27 27 27 28 29 29 30 30 30 31 31 32 33 11i V Reference Figure Figure Table Figure Figure Table Figure Table Figure Table Figure Table Figure Table Figure Table Figure Table Figure Table Figure Table 1 1 ied 3 1 3 1 3 2 3 2 3 3 4 1 died 5 1 5 2 5 2 5 3 5 3 5 4 5 4 202 555 3 6 5 6 Table of Illustrations Description Model 520 Cryogenic Temperature Controller Model 520 Sensor Connection to Instrument Sensor Connections Typical RM 3F and RM 5F Rack Mounting Installation Modei 520 Cryogenic Temperature Controller Front Panel Functional Description of the 520 Front Panel and Rear Panel Features Model 520 Cryogenic Temperature Controller Rear Panel Parallel BCD Output of Sensor Voltage Input of Set Point Temperature Versus Time Characteristics of Controller Translation of Null Error Versus Set Point Deviation Component Layout Al Main PCB Troubleshooting Guide for Model 520 Schematic Al Main Schematics Parts List Al Main PCB Assembly Schematic Al Output Section Parts List A2 Front Panel Assembly Schematic Al Power Supply Parts List A3 Rear Panel Assembly Component Layout Model 5201 BCD Option PCB Parts List A4
32. control of the heater output current is available from the front panel Additionally the user can manually add a fixed current to the controlled current This manual offset often produces improved control in relatively stable systems and applications since all the heater power is not contributed via Controller gain The 520 can be used to accurately measure temperature by being operated in the open loop mode The sensor is nulled against the set point using the built in meter thus the set point becomes a read out of the actual sensor signal either voltage or resistance Referral to the V T or R T calibration table for the particular sensor yields the actual temperature reading in the resistance mode the set point is directly in ohms thus the user is freed from constant use of Ohms Law to read or control tempera tures n the diode mode the set point is calibrated in volts since most diode temperature calibrations are provided as voltage as a function of temperature at a constant current Multi sensor inputs for the Model 520 are possible with the accessory Model SW 10A Sensor Selector Up to 10 sensors can be connected to the 520 Selection is made via front panel pushbuttons on the SW 10A Lao General Specifications The following specifications for the Model 520 Cryogenic Tempera ture Thermometer Controller are applicable when used with cryogenic thermometers Input Temperature Range 1 4 to 380K with Lake Shore DT 500
33. de Res Switch for selecting diode temperature Res sensor or resistive temperature sensors with either positive or negative temperature coefficient for their R vs T curves 15 NULL SENSOR Indicates the difference between the VOLTAGE set point voltage and the sensor output voltage Meter is non linear for large errors of either sign See page and for discussion 16 SENSOR CURRENT Selector switch for determining the level MICROAMPERES of dc current for the temperature sensor IOLA is recommended for diode sensors 17 115 230 VAC A C line voltage selector slide switch 50 60 Hz 75A SB A RA line fuse FUl 115 VAC 0 75 230 VAC 0 4 AMP acme NO LABEL A C line cord RESISTANCE HIGH LOW LA HE 23 HEATER Heater element lead terminals Grey is HIGH LOW the HIGH side and black is the LOW side NO LABEL Heat sink for output transistor 25 NO LABEL Potentiometer used for setting the resistive sensor voltage limit See Key No 2 26 J2 40 pin connector for REMOTE BCD in out option 27 Jl Sensor cable receptacle 14 pin LSCI 1106 142 See Table 2 1 for sensor s connections Selector switch to match load resistance to controller output stage HIGH is for a load greater than 10 ohms 25 ohms optimum LOW is for a load of 10 ohms or less 10 ohms optimum Heater element line fuse 1 AMP Fast Blow 13 SENSOR CURRENT amp Lake ShoreCryotronics
34. ected Key No 16 and indicates decimal point and maximum range of set point resistance Gain Multiplier xl x3 x10 x30 and x100 Elis 315 E i Control Mode Heater Current Variable gain 1 10 Together with gain multiplier allows adjustment of overall controller gain over 1000 to l range MAN position permits user to control the current to the heater with the heater current knob Key No 8 AUTO uses controller to set output power to force error signal to zero MIX allows both a manual output com ponent as well as an error component of output power Sets the amount of manual heater cur Control rent when the Control Mode is either MAN or MIX Reset Adjusts auto reset time constant of integrator Effectively determines time constant of integrator between 100 and 1 seconds MIN and MAX respectively or OFF 10 Rate Adjusts auto rate time constant of differentiator Effectively sets differentiator time constant between l and 100 seconds MIN and MAX respectively or OFF 11 A C line switch ON OFF and pilot light 12 HTR CURRENT RANGE Switch selected current selector Use MILLIAMPERES of a low setting will avoid inadvertent boil off in setting up system and or system oscillations Monitors heater element current Full scale deflection corresponds to HTR CURRENT RANGE switch Key No 12 setting 13 HEATER CURRENT 14 Dio
35. election of any one of up to 10 sensors Dimensions 216mm wide x 102mm high x 330mm deep 8 in x 4 in x 13 in Style L half rack package Model RM 3H Rack mount kit to mount either one or two SW 10A in standard 3 in rack space Model RH 5F Rack ears with handles to mount Model 520 in standard 5 in rack space 1 6 Temperature Sensors Model DI 500 Silicon Diode Sensors Refer to Lake Shore Series DT 500 Technical Data for details DT 500K DT 500P GR DT 500KL DT 500FP DT 500K TO5 DT 500P GR Mini DT 500KL TO5 DT 500FP HRC 6 DT 500P DT 500FP HRC 7 DT 500CU 36 DT 500DRC DT 500 CU DRC 36 Model TG 100 GaAs Sensors Refer to Lake Shore TG 100 Technical Data for details TG 100P TG 100FP Model CGR 1 Carbon Glass Resistor Sensors Refer to Lake Shore CGR 1 Technical Data for details CGR 1 500 CGR 1 2000 CGR 1 1000 CGR 1 3000 CGR 1 1500 Model GR 200 Germanium Resistor Sensors Refer to Lake Shore GR 200 Technical Data for details GR 200A 30 50 100 250 500 GR 200A 1000 1500 2500 5000 GR 200B 500 1000 1500 2500 5000 Model PT 100 Platinum Resistance Sensors Refer to Lake Shore PT 100 Technical Data for details PT 101 PT 103 PT 102 PT 1001 Sensor Calibration Other ranges also available Type Range K Type Range K OSOJA V 68 eeu 0 05 6 0 A see ice 1 4 300 O LA ran 0 1 6 0 1 4G 1 4 380 E e 0 3 6 0 4B 4 0 40 EA pa aed abs 4 050 GE emek 4 0 300 LAB sev L 40 4G
36. er the transient response of the system must be improved this can be done by the addition of rate or derivative to the control functions Physically the effect can be described as introducing anticipation into the system The system reacts not only to the magnitude and integral RESET of the error but also its probable value in the future If the error is changing rapidly then the controller responds faster The net result is to speed up the response of the system To increase system response if needed take the RATE control Key No 10 out of the detent off position in tbe clockwise direction For various settings of the control observe the transient response to a change in set point Too short a time constant may result in oscillation and an unstable system A change in gain may be necessary to eliminate oscillation or overshoot 3 6 MAN and MIX Control Mode By placing the Control Mode switch Key No 8 in either MAN or MIX a manually settable constant current may be supplied to the heater element The magnitude of the current is determined by the setting of the 17s 18 MAN HEATER current potentiometer Key No 8 and the HTR CURRENT RANGE Key No 12 The current supplied to the heater is indicated on the HEATER CURRENT meter The full scale reading of the meter corresponds to the HTR CURRENT RANGE switch setting MAN HEATER CURRENT MODE allows the user to hold a temperature for a short period of time in an open
37. h R114 to equal the voltage developed across R99 The output current is therefore only dependent on the voltage developed across R99 and the magnitude of the selected range resistor The zener CR16 limits the voltage across U24 to 24 volts on the high load resistance range Switch S9 Heater Current Metering The heater load current is measured by the heater cur rent ammeter shunted by resistor R103 through R107 as appropriate Approximately 5 volts appears across the the Heater Current Meter M2 and its appropriate shunt resistor SECTION V Maintenance and Calibration 5s1 Introduction This section contains maintenance and calibration information for the Model 520 This section also includes an illustrated parts breakdown as well as schematics for the unit Dae General Maintenance Clean the 520 periodically to remove dust grease and other contaminants A Use the following procedure Clean the front and back panels and case with a soft cloth dampened with a mild detergent and water solu tion Caution Do nor use aromatic hydrocarbons or chlorinated solvents to clean the 520 They may react with the plastic materials used in the unit or the silk screen printing on the front and back panels Clean the surface of the printed circuit boards pcb using clean dry air at low pressure If grease is encountered spray with Freon T F degreaser and re move grime with dry low pressure air 54 3 Access Informati
38. igure 2 2 Typical RM 3F amp RM 5F Rack Mounting Installation SECTION III Operating Instructions Sul Introduction This section contains a description of the operating controls and their adjustments under normal operating conditions These instructions are predicated upon the instrument having been installed as outlined in The diode polarity as shown in Figure 2 1 in particular must A diode sensor and or a resistance thermometer is assumed to Section II be correct be connected as shown in Figure 2 1 In addition a resistive heating element is assumed to have been connected to the Heater terminals Figure 3 2 Key No 23 3 2 Controls Indicators and Connectors The operating controls indicators and connectors on the instru ment s front and rear panels are shown in Figures 3 1 and 3 2 The numbers with leaders to various controls in the figures are keyed to the entries in Table 3 1 N o kk m KA SET POINT VOLTS SET POINT OHMS 0 39 999 399 99 3999 9 or 39999 Sensor Voltage Alert Volts LED Ohms decimal LED s Digital set point of sensor voltage Digital set point of sensor resistance LED turns on in the resistance mode when the voltage limit has been exceeded Fully counterclockwise is approximately 1 mV fully clockwise is approximately 40 mV LED turns on to indicate decimal point when in the diode mode Key No 14 LED which is on depends on the Sensor Current sel
39. ind that usually accompany high vacuum pumping systems 2 5 2 Rack Mounting The Model 520 can be installed in a standard 19 instrument rack by using the optional rack mounting kit RM 5H The basic hardware and front handles are contained in the RM 5H kit A typical rack mount installation is shown in Figure 2 2 2 6 Sensor and Heater Connections 2 6 1 Sensor Input Connections The 520 is supplied with a 14 pin male connector LSCI Stock 1106 070 and 12 pins 4 spares LSCI Stock 106 060 which mate with connector Jl on the rear panel Figure 3 2 Key No 27 page 14 This connector interfaces both a resistance thermometer and a diode thermo meter to the Model 520 Thermometer Controller Table 2 1 lists the pin assignments for the connector Figure 2 1 shows the sensor connections for both the diode and resistance thermometers The recommended cable diagrams for the sensor diode and resistance thermometer are given in Figure 2 1 The use of a four wire diode connection is highly recommended to avoid introducing lead IR drops in the voltage sensing pair which is translated into a temperature measurement error or a control offset from setpoint temperature The alternate wiring scheme shown in Figure 2 1 may be used for the diode in less critical applications where control is important but small temperature offsets can be tolerated 2 6 2 Heater Connections The power output stage is a current drive with a maximum current
40. iscarding any shipping material In case of part s shortages please advise LSCI Ihe standard LSCI warranty as given in the front of this manual is appli cable to the Model 520 za Power Requirements Before connecting the power cable to line voltage verify that the instrument is set for the proper line voltage and fused accordingly The line voltage and fuse data are shown on the rear panel of the instrument adjacent to the fuse holder The line voltage can be changed by switching line selector switch 52 located on the rear panel Figure 3 2 Key No 17 Page 14 Nominal permissible line voltage fluctuation is 10 at 50 to 60 Hertz 2 4 Grounding Requirements 2 4 1 Instrument Grounding To protect operating personnel the National Electrical Manu facturer s Association NEMA recommends and some local codes require instrument panels and cabinets to be grounded This instrument is equipped with a three conductor power cable which when plugged into an appropriate receptacle grounds the instrument 2 4 2 Temperature Sensor Grounding Refer to Figure 2 1 for illustrated individual sensor wiring configurations recommended for optimizing system performance 255 Instrument Installation 2 5 1 Bench Use The Model 520 is shipped with feet and a tilt ball installed and is ready for use as a bench instrument As with any precision instrument the 520 should not be subjected to excessive shock and vibrations such as the k
41. le the power dissi pation for a germanium or carbon glass resistance thermometer is measured in nanowatts power dissipation for a platinum resistance thermometer is measured in microwatts The recommended power dissipa tion for a platinum resistance thermometer is lO microwatts or less For a 100 ohm platinum this corresponds to l milliampere at the lower temperatures and 300 microamperes at or near room temperature If a diode thermometer is used for control its voltage signal is first buffered and then inverted in sign If a resistance thermo meter is used for control its millivolt signal is amplified by 100 and inverted in sign by means of an instrumentation amplifier which makes its magnitude and sign the same order of magnitude as the voltage signal from a diode thermometer In the case of a resistance thermometer the output from the in strumentation amplifier is compared to the sensor alert voltage and if that output exceeds the user selected value the sensor alert LED is lit to indicate that the voltage across the sensor has exceeded the user set limit This comparator does not introduce an error or offset in the sensor voltage signal under any conditions D 0 The digital set point is converted to an analog voltage by using two three digit D A converters One converter transforms the three most significant digits to its corresponding voltage and the other converter transforms the two least significant digits to its corre
42. loop condition while he uses the null meter and the digital set point to a second sensor This is accomplished by adjusting the MAN HEATER current Key No 8 such that the heater current Key No 13 does not vary when switched from Auto to MAN or MIX Key No 7 The MIX mode can be useful under certain conditions where the load on the controller is not varying by much and very good stability of the control point is desired In some systems by using the manual reset to provide most of the desired output power the control parameters of the controller i e gain in particular may be increased so as to significantly improve the stability of the control point Please note that the control circuit can both add and subtract power from the manual reset power setting 3 7 Remote Parallel BCD Input Output Option The remote programming option consists of a TTL parallel 18 bit input of set point voltage and a TTL parallel 17 bit output of one half of the sensor voltage It is assumed that the sensor voltage output can be multiplied by two within the computer The cable pin out connections are indicated in Tables 3 2 and 3 3 The internal and external BCD input of the set point is accomplished by setting connector J2 pin 38 high 5V for external BCD or low 0 V for internal BCD The BCD output of one half of the sensor voltage is present at all times independent of the internal or external status of the BCD set point input 3 8 Grounding
43. ly deflect off scale either left or right when the power switch is turned on If either a diode or a nega tive temperature coefficient resistor RES is being monitored and the deflection is to the right the set point voltage or resistance is less than the sensor voltage or resistance If the deflection is to the left the set point voltage or resistance is greater than the sensor voltage or resistance Therefore in order to null the meter turn the set point in the direction that you wish the needle to move If you are monitoring a platinum resistor which has a positive temperature coefficient RES the above instructions must be reversed with regard to sign If the null meter will not null regardless of the set point value check to make sure that the printed circuit card located behind the thumb wheel digits has not worked loose from its proper position during shipping This possibility can easily be observed by removal of the top cover Adjust the set point until the NULL meter is centered while in creasing the GAIN toward maximum Increasing the set point will move the meter pointer to the left decreasing the set point will deflect the meter pointer to the right After centering the meter pointer at zero the set point can be read directly to 100 uvolts for diodes and to five places for resistors A table of relative sensitivity for the null meter as a function of gain setting for diodes is given in Table 4 1 After determini
44. ng the set point refer to the appropriate sensor calibration chart to ascertain the sensor temperature 15 Ge v5 Constant Temperature Control Mode Assume that a calibrated sensor is to be used as described in paragraph 3 4 To maintain a constant temperature determine the corres ponding set point from the sensor calibration chart Set this voltage on the SET POINT switches Position controls as indicated below Sensor Selector Switch Key No 14 to type of sensor CONTROL MODE switch Key No 7 to AUTO HIR CURRENT RANGE Key No 12 to 1000 milliamperes GAIN Key Nos 5 and 6 to minimum settings RESET Key No 9 to off RATE Key No 10 to off SET POINT switch Key No 1 to set point corresponding to desired temperature H POWER switch Key No 11 to on QAO gt gt If the block or sample holder whose temperature is to be controlled is colder than the set point temperature the null meter will deflect to the right Slowly increase the GAIN setting Key Nos 5 and 6 The HEATER CURRENT meter should show an immediate up scale deflection propor tional to the GAIN setting The NULL meter should start to come off its full right deflection position as the gain is increased As the sample holder temperature approaches the set point temperature the NULL meter will approach center scale and the HEATER CURRENT meter will assume a steady value even with a further increase in the gain setting Co
45. ntinue to in crease the gain until an incremental change in gain produces a negligible reduction in the null error but not so high as to produce oscillations To further reduce the null error rotate the RESET gain control Key No 9 out of the detent off position in the clockwise direction As the control is advanced the null meter should approach the center position with unobservable error Leave the RESET vernier in the position required to reduce the null error to zero but below any level which induces oscillations After achieving a stable operating point reduce the HTR CURRENT RANGE switch Key No 9 to a lower setting As lower settings are dialed in the per cent Z of maximum heater current being used should increase The optimum area for control can be obtained by keeping the meter pointer between 0 2 and 0 7 on the meter face Abruptly decrease the set point temperature by 5 Kelvin The sensor temperature now represents a temperature warmer than that represented by the set point The NULL meter should deflect to the left and the HEATER CURRENT should go to zero immediately As the sample holder cools the NULL METER pointer should return toward zero As the NULL METER pointer approaches zero the HEATER CURRENT will increase from zero to the new steady state value required to maintain the sample at the lower temperature requested The NULL METER should read zero as the HEATER CURRENT stabilizes at its new value Now ab
46. on Jade i Fuse Replacement The line fuse is accessible from the rear of the 520 Use the following procedure to check and or replace the fuse A Set the POWER switch of OFF and unplug the unit The fuse holder is located on the back panel just above the power cord Gently push in on the cap of the fuse holder and turn counter clockwise and remove from holder Remove and inspect fuse If replacement is required use MDL 3 4 amp fuse for 90 125 VAC operation and MDL 4 10 amp fuse for 210 250 VAC operation x TE c D Insert fuse and cap into fuse holder push in and turn clockwise to lock cap in place 3432 Model 5201 BCD Option Installation The installation of the Model 5201 BCD option is performed as follows A Remove instrument cover B Locate and remove shorting pcb installed in internal edge connector J8 see Figure 5 1 Component Layout Al Main PCB C Insert the Model 5201 pcb into connector J8 the board is configured such that the option board can be in stalled in only one way with the components side to the front of the unit and connection cable to the back D Route 40 pin ribbon connector to rear panel access slot J2 and secure with screws provided E Replace instrument cover 5 4 Operational Checks Replace the temperature sensors shown in Figure 2 1 with precision resistors to simulate the sensors Remove the heater element leads and place a 25 watt 25 ohm resistor across the heater
47. output terminals With the Diode selected as the sensor and a 100K ohm resistor in place of the diode set the sensor current selector switch to 10 micro amperes A potential of 1 00 volts should be developed across the resistor With the gain set to a high value and the Control Mode selector switch set to MAN attempt to null the error with a set point in the vicinity of 1 0 volts The null meter should swing smoothly as the set point voltage is varied in the vicinity of the null While still in the MAN position set the HTR CURRENT RANGE switch to 1000 Vary the Heater Current Control potentiometer from zero toward its maximum The current meter should increase linearly along with the advance of the pot With the Heater Current Control pot set to give mid scale heater current meter deflection rotate the HTR CURRENT RANGE switch through all of its positions The heater current meter indication should remain approximately at mid scale in all of the positions Zero the null meter with the set point voltage controls Turn the RESET and GAIN controls to mid scale position Set the HTR CURRENT RANGE switch to 1000 Position the mode control switch to AUTO Abruptly change the set point voltage sufficiently to cause a 10 unit deflection of the NULL meter to the right The heater current meter deflection will consist of two components The first is a rapid step rise due to the steady null error and a second gradually rising component due to the RES
48. ra CA 95051 408 737 5000 PAN PLSY PMI SFT SIL SPRG SPTX TECO Panasonic Co E C D P O Box 1503 Seacaucus NJ 07094 201 348 5230 Plessey Capacitors Inc 5334 Sterling Center Dr WestLake Village CA 91361 213 889 4120 Precision Monolithics Inc 1500 Space Park Drive Santa Clara CA 95050 408 246 9222 Standard Grigsby Inc 920 Rathbone Ave Aurora IL 60507 312 844 4300 Switchcraft 5555 N Elston Ave Chicago Il 60630 312 792 2700 Siliconix 2201 Laurelwood Road Santa Clara CA 95054 408 246 8000 Sprague Products Corp 551 Marshall Street North Adams MA 01247 413 664 4481 Supertex Inc 1225 Bordeaux Drive Sunnyvale CA 94086 408 744 0100 TECO Corporation P O Box Winnesquam NH 03289 603 524 1998 TI VISH Table 5 10 cont d Cross Reference of Parts Manufacturers Texas Instruments Inc P O Box 22512 Dallas TX 75265 Vishay 63 Lincoln Highway Malvern PA 19355 215 644 1300 63
49. rs Place the digital voltmeter across the precision resistance Select the current range to be checked the corresponding voltage read on the volt meter is given by V I x R where I is the current selected and R is the precision resistance Below is listed the current ranges and adjustment trimpots for each range Adjust the proper trimpot for that range to achieve the desired voltage across the precision resistance 29 Sensor Current microamperes Adjustment Trimpot 1 R4 3 R5 10 R6 30 R7 100 R8 300 R9 1000 R10 3 32 Set Point A Place voltmeter from Analog Ground to the output of the most significant Set Point DAC Pin 15 or 19 of Ul5 B Dial a set point of 0 0000 on front panel set point switches C Adjust trimpot R39 until voltmeter zeroes past the 100uV place Dial a set point of 3 9900 Adjust R38 until voltmeter reads 3 9900 V F Place voltmeter at output of set point DAC summing amplifier Pin 10 of Ul8 G Go between minimum and maximum values of set point and adjust trimpot R52 for optimum linearity 3 9 99 Diode Input Buffer A Select diode as the type of sensor B Apply a voltage source across the diode voltage input pins Jl pin 2 is V pin 3 is V C Place a voltmeter from ground to pin 10 of Ul4 D Input a voltage of 4 0000 volts from the voltage source Adjust R35 to read 4 0000 volts on the voltmeter F Scan the range between a 0 0000 volts and 4 0000 volts to ass
50. ruptly increase the set point vernier control by 5 Kelvin Ihe sensor voltage or resistance now represents a temperature colder than that represented by the set point The NULL meter should deflect to the right and the HEATER CURRENT meter should deflect toward full scale s the sample holder heats the NULL meter pointer will tend to zero and the HEATER CURRENT meter reading will decrease toward its new steady state value As the NULL meter centers the HEATER CURRENT should stabilize at the new constant value required to maintain the desired temperature A sketch of the temperature versus time pattern described above is given in Figure 3 3 Observe that there is no temperature overshoot or oscillation when the GAIN and RESET controls are properly adjusted Ihis statement presupposes that the sample holder heater and sensor may be accurately modeled as a simple R C type time constant thermal circuit If oscillation or overshoot are observed when changing the set point voltage in small increments reduce the GAIN and increase the RESET time constant rotate CCW settings until oscillations are no longer observed and or adjust the HTR CURRENT RANGE Key No 12 to a lower setting Normally at cryogenic temperatures the above adjustments will result in a stable system with good transient response due to the short time constants encountered at these temperatures For these constants the rate switch should remain in an off position If howev
51. s input voltage If it has in put voltage but no output replace the regulator If it has no input voltage check to see if there is AC voltage at the input of the rectifier for that supply If there is AC in put and no DC output replace the rectifier If there is no input replace TX1 2 No Sensor Current l No reference Verify that the output of the reference pin 1 to pin 2 of U8 is approximately 6 95 V If it is not then replace U8 3 Instrument doesn t null properly l Verify that the shorting board or a BCD option board is plugged into J8 Set point problem Verify that the output voltage of U18 pin 10 to GND corresponds to the set point switches on the front panel If it doesn t then check to see if the voltage is at the output of U19 pin 10 to GND If it is replace Ul8 If it is not then verify the output of the digital to analog converters Pins 15 19 of U15 to GND should corresond to the three most significant digits of the set point Pins 15 19 of U16 to GND should Table 5 1 cont d Troubleshooting Guide for Model 520 Symptom Possible Cause Corrective Action correspond to the two least significant digits of the set point If the voltages are present replace Ul7 If the voltage at one or both of the DAC outputs is not there verify the digital code inputs If the input codes are correct replace the
52. sponding voltage These two voltages are summed by means of a summing amplifier and then inverted again to result in a positive voltage signal which is opposite in sign from the processed sensor voltage The processed negative sensor voltage and the positive set point voltage are then summed through two selected precision resist ors and amplified by a gain stage with a range of 1000 to I The result is zero current at the summing junction when the set point voltage is just equal in magnitude to the processed sensor voltage If a difference exists between these two voltages this error signal because of the virtual ground of the gain amplifier becomes a current which is amplified as a voltage by the variable gain operational amplifier Ul9 This amplified voltage error is displayed on the NULL meter and also applied through an inverter to 1 an integrator cir cuit reset 2 a bound or clamping circuit and 3 a differentiator circuit rate in the case of a diode sensor or a negative temperature coefficient resistance thermometer In the case of a positive temp erature coefficient resistor the sign of the error signal is reversed and the inversion of the amplified error signal must be avoided so that the control circuit will add power when the sensor temperature is below the set point temperature and reduce power when the sensor temp erature is high compared to the set point temperature The amplified error signal its integral and differen
53. summed by operational amplifier Ul7 the ratio of R49 R48 is chosen to be 100 Operational amplifier U18 is an inverter to correct the sign of the summed voltages while R52 is a trimpot to adjust the magnitude of the summed voltages to correct for the accuracy specifications of the resistors used for these two amplifiers 23 nA Summing Variable Gain Amplifier The negative processed sensor voltage and the positive set point voltage are summed and amplified by the var iable gain amplifier U19 Two precision selected re sistors R37 and R58 or R56 R57 in place of R58 are used to create an error signal current which is amplified by the amplifier to give an amplified error signal Switch wafer SIC and R56 through R58 allow the set point to read directly in resistance by scaling the set point current with the sensor current Capacitor C13 is present for high frequency stability The chopper stabilized amplifiers U19 Ul3 Ul4 U17 and U18 achieve their low offset by comparing the invert ing and non inverting input voltages in a nulling ampli fier nulled by alternate clock phases For the gain amplifier U19 this charge is stored on capacitors C29 and C30 with corresponding capacitors for the other four amplifiers The gain range is determined by switch S3 and resistors R6l through R64 The variable gain range is controlled by trimpot R67 with the total feedback circuit consist ing of resistors R59 through
54. tage of supply P S 1 by an inter nally temperature stabilized precision voltage refer ence U8 whose current is set by resistor R3 Resistors R4 through R22 together with switch wafer SIA set the appropriate current on each range together with the feedback circuit which consists of operational amplifier U9 and the p channel FET 010 This current is directed to the appropriate sensor by means of switch S2 Trimpots R4 through R11 adjust the current independent of each other for their appropriate value as shown on Figure 5 2 The entire constant current supply was designed to be fully floating so that the sensor can be at a potential different from ground potential Set Point Voltage The digital set point consists of two digital to analog converters which in combination give a set point linear ity of better than 0 025Z The three digit D A converter Ul5 converts the three most significant digits to their equivalent voltage Since this conversion must be accurate to two orders of magnitude beyond its least significant digit in order to add the two least signifi cant digits of the set point without error both the zero and the gain of Ul5 must be trimmed The zero is adjusted by trimpot U39 and the gain is adjusted by means of trim pot U38 The two least significant digits of the set point are input to the two least significant digits of the three digit D A converter Ul6 Therefore when the re sultant voltages of the two converters are
55. tial are summed as current by the operational amplifier U23 This amplifier then drives the output power circuit The current from the power amplifier is metered by the output current meter Changing the current range from 10 mA to 1 Amp changes the voltage gain of the output stage from 0 1 to 10 Closed loop control action is achieved through the thermal path between the heater element and the temperature sensor 4 3 Detailed Description A Power Supplies There are seven regulated supply voltages within the Model 520 They are designated as P S 1 through P S 7 Figure 5 4 P S 1 consisting of a diode bridge CRI and regulator Ul supplies a regulated 15 volts and an unregulated 20 volts to the circuit comprising the con stant current source and its associated switching P S 2 through P S 5 consist of diode bridge CR2 with regulators U2 through U5 which supply 15 8 8 and 15 volts respectively The 15 volt supplies power the D A converters while all the amplifiers run off 78 volts P S 6 consisting of diode bridge CR3 and regulator U6 supplies the 5 volts for the D A con vertors and the BCD option P S 7 consisting of switch S9 half wave rectifier diodes CR4 and CR5 and regulator U7 supply the regu lated output power stage The output voltage is approximately 16 volts on the low scale and 33 volts on the high scale Constant Current Supply A precision reference voltage is generated with respect to the positive vol
56. ure linearity Db cd Resistor Input Amplifier A Select resistor as the type of sensor B Apply a voltage source across the resistor voltage input pins Jl pin 12 is V pin 13 is V 30 Place a voltmeter from ground to pin 9 of Ull D Input a voltage of 0 000 millivolts from the voltage source Adjust R24 until voltmeter reads 0 0000 V Input 40 000 millivolts G Adjust R27 until voltmeter reads 4 0000 V Su 3X Current Summing Select resistor as the type of sensor B Input 30 000 millivolts to resistor input leads Jl pin 12 is V pin 13 is V C Dial in 1 0000 on set point switches Select a 3X current source setting 3 30 300 or 3000 microamperes E Set gain to X100 Adjust R57 until null meter nuils at its center position 5 6 Troubleshooting When troubleshooting the 520 use the following precautions to prevent damage due to static discharge A Set the 520 POWER switch to OFF before removing or in stalling components or pbcs B Minimize handling of static sensitive components C Use ground straps to discharge repair personnel static before handling devices D Use conductive or anti static containers for storage and transport of components or circuit boards E Keep parts in their original containers F Pick up static sensitive components only by the body G Do not slide static sensitive components over any surface H Avoid plastic vinyl and styrofoam in the work area
57. utomatic Rate Circuit For most cryogenic applications the addition of rate will not greatly enhance the system response However in some applications rate may be extremely useful The blocking capacitor C34 will only pass a signal for a rapidly varying input The rate potentiometer R89 allows the time constant of that differentiator to be varied over nearly two orders of magnitude With the RATE switch closed the circuit is effectively disabled from the controller since the gain is less than 0 001 Output Power Amplifier The output power stage consists of a summing amplifier U23a and a current mirror with its associated current network an output current limit network and a heater current metering circuit The summing amplifier U23a adds the currents from the gain reset and rate stages through R83 R84 and R85 when in the AUTO or MIX mode Switch S4 dds in manual reset under the MIX or MAN positions through the resistor group R91 R92 and R94 The zener and diodes CR17 CR18 and CR19 limit the amplifier output The buffer amplifier U23b transfers this voltage to the resistor R98 and through the series string to R99 and the FET U25 The resistors R96 and R97 are present to provide a load to the buffer amplifier and for stability The output amplifier U24 drives the output FET U26 such that the current in the output circuit is mirrored to the output by establishing the voltage across the selected range resistor R109 throug
58. wn 714 835 6000 Intl Airport Ind Park P O Box 11400 EFJ E F Johnson Company Tucson AZ 85734 Components Division 602 746 1111 299 Tenth Ave S W Waseca MN 56093 BEL Belden Electronic Div 507 835 6222 Belden Corp Richmond IN 47374 FLD Fairchild 474 Ellis Street BOR Bourns Inc Mountain View CA 94042 1200 Columbia Ave 415 962 5011 Riverside CA 92507 714 781 5050 GE General Electric Company Semiconductor Products Dept Electronics Park BUC Buckeye Stamping Co Syracuse NY 13201 555 Marion Rd Columbus OH 43207 614 445 8433 HHS IR ISL JWL LIT LSCI MEP EL 3M NAT 62 Table 5 10 cont d Cross Reference of Parts Manufacturers H H Smith 812 Snediker Avenue Brooklyn NY 11207 212 272 9400 International Rectifier Semiconductor Division 233 Kansas Street El Segundo CA 90245 213 772 2000 Intersil Inc 10710 N Tantau Ave Cupertino CA 95014 408 996 5000 Jewell Electronics inc Grenier Field Box 4038 Manchester NH 03108 603 669 6400 Littlefuse Inc 800 E Northwest Highway Des Plaines IL 60016 312 824 1188 Lake Shore Cryotronics Inc 64 East Walnut Street Westerville OH 43081 614 891 2243 Mepco Electra Inc 6071 St Andrews Rd Columbia SC 29210 803 772 2500 3M Electronic Prods Div 3M Center St Paul MN 55101 612 733 3351 National Semiconductor Corp 2900 Semiconductor Drive Santa Cla
59. y Left Blank SECTION II Installation Zl Introduction This section of the manual contains the necessary information and instructions for installation of the Model 520 Cryogenic Tempera ture Thermometer Controller Included are the initial inspection procedures power requirements recommended grounding connections interface connector diagrams along with pin designations and recom mended temperature sensor connections 22 Initial Inspection This instrument was carefully inspected both mechanically and electrically before shipment It should be free of mars or scratches and in perfect electrical order upon receipt Immediately upon receipt the instrument should be inspected for any damage that may have occurred in transit If the shipment container or cushioning material is damaged it should be kept until the contents of the shipment have been checked for completeness and the instrument has been mechanically and electric ally checked Procedures for checking the electrical performance of the 520 are given in Section V If there is mechanical damage or the instru ment does not perform electrically notify LSCI immediately If the shipping container is damaged or the cushioning material shows signs of stress be sure to file appropriate claims with the carrier and or insurance company and notify LSCI of the claims filing Save the ship ping materials for inspection by the carrier Be sure to inventory all components supplied before d
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