YSI Model 85 - John Morris Scientific
Contents
1. 32 SECTION 6 WARRANTY AND REPAIR 33 Appendix A Accessories and Replacement Parts 1 eee 37 Appendix B Temperature Correction Data 4 sette setae sena 39 41 1 SECTION 1 INTRODUCTION The YSI Model 85 Handheld Salinity Conductivity Dissolved Oxygen amp Temperature System is a rugged microprocessor based digital meter with an attached YSI combination conductivity and dissolved oxygen probe The YSI Model 85 is designed for use in field lab and process control applications as well as for environmental aquaculture and industrial uses The Model 85 is available with cable lengths of 10 25 50 or 100 feet The body of the probe has been manufactured with stainless steel to add rugged durability and sinking weight The probe also utilizes our easy to install cap membranes for measuring dissolved oxygen The YSI Model 85 probe is a non detachable combination sensor designed specifically for the YSI Model 85 Handheld System The conductivity portion is a four electrode cell with a cell constant of 5 0 cm 4 The dissolved oxygen portion is a polaragraphic clark type sensor The Model 85 s microprocessor allows the system to be easily calibrated for dissolved oxygen or conductivity with the press of a few buttons Additionally the microprocessor performs a2. Place the probe in its calibration chamber Turn the system on and allow it to stabilize for 30 minutes Calibrate the system as described in the Calibration Section of this manual DN OO mu MES With the probe in the calibration chamber check the displayed reading for stability Erratic or drifting readings indicates a possible problem See the Troubleshooting Section for help 7 Place the probe in a zero oxygen environment The display should decrease rapidly and reach 0 2 0 in 5 minutes or less Note A zero oxygen environment can be obtain by taking a reading in pure nitrogen gas in a sodium sulfite solution or ina BOD bottle filled with 350 ml of distilled water in which 3 to 7 grams of active dry yeast has been dissolved and allowed to consume the oxygen about 5 minutes YSI Incorporated 85 Service Manual 21 Troubleshooting and Maintenance Section 4 CONDUCTIVITY Functionality of the Model s 85 conductivity system can be tested using the following procedure 1 Ifnecessary service the probe s electrodes See Section 4 Troubleshooting and Maintenance 2 Verify that the Temperature Coefficient and Reference Temperature are properly set 3 Use clean properly stored NIST traceable calibration solutions to very the accuracy of the system See Section 3 2 System Calibration for procedures TEM PERA TURE Compare the 85 s measured temperature value to that of a known traceable temperature sta
3. Contamination or physical damage to the cell can alter the cell constant Performing a calibration will eliminate any error that might arise because of cell constant change YSI cells are calibrated to within one percent of the stated cell constant at a single point We consider these products to be usefully linear over most instrument ranges The cell constant can be calibrated to 0 35 accuracy with YSI conductivity calibrator solutions Temperature Error 1 maximum The solution temperature error is the product of the temperature coefficient and the temperature offset from 25 expressed as a percentage of the reading that would have been obtained at 25 The error is not necessarily a linear function of temperature The statement of error is derived from a 25 C temperature offset and a 3 temperature coefficient Total Error YSI Incorporated 85 Service Manual 18 Troubleshooting and Maintenance Section 4 Considering only the above three factors system accuracy under worst case conditions will be 2 although the actual error will be considerably less if recommended and properly calibrated cells and instrument ranges are used Additional errors which can essentially be eliminated with proper handling are described below Cell Contamination This error is usually due to contamination of the solution being measured which occurs when solution is carried over from the last solution measured Thus the instrument might be correc
4. and Secondary display reads ovr B Temperature reading is gt 95 C procedures check advanced setup Secondary display readn udr C Temperature reading is 5 C settings D Salinity reading is gt 80 ppt E User cell constant cal K is 25 25 If each of these is set correctly see the DO temperature is gt 46 Test chapter to determine if problem is DO saturation is 220046 circuit or probe related H DO concentration is 220 mg L 9 Main display reads A User cell constant cal K is 4 8 A Recalibrate instrument using known good conductivity standard B Follow cell cleaning procedure in the Maintenance chapter 10 Main display reads rErr A Reading exceeds user selected A Use the mode key to select a higher or manual range lower manual range or set system to autoranging 11 Main display reads A User cell constant cal K is 0 0 A See Advanced Setup chapter B Incorrect sequence of keystrokes B Refer to manual section for step by YSI Incorporated 85 Service Manual 25 Troubleshooting and Maintenance Section 4 SYMPTOM POSSIBLE CAUSE ACTION step instruction for the function you are attempting 12 Main display reads LErr A In temperature compensated A amp B Adjust user defined tempco or conductivity mode temperature reference temperature exceeds the values computed using user defined temperature coefficient and or reference temperature B In cell con
5. directed at determining the condition and functionality of the probe and cable In the event that a service problem is isolated to the meter itself YSI recommends the replacement of the entire defective sub assembly rather than individual components To lessen down time YSI maintains an adequate stock of replacement sub assemblies The recommended method of determining a sub assemblies condition is by substitution For example to test for a defective probe cable assembly substitute the assembly with a known good assembly or a decade resistance box If after testing the PCB meets the established specifications the probe cable assembly will have to be serviced or replaced 12 SPECIFICATIONS Operating Environment Medium fresh sea or polluted water and most other liquid solutions Temperature 5 to 65 C Depth 0 to 10 0 to 25 0 to 50 or 0 to 100 feet depending on cable length Storage Temperature 10 to 50 C Material ABS Stainless Steel and other materials Dimensions Height 9 5 inches 24 13 cm Thickness 2 2 inches 5 6 cm Width 3 5 inches max 8 89 cm Weight 1 7 pounds w 107 cable 77 kg Display 23 5 8 W 3 8cm Power 9 VDC 6 AA size Alkaline Batteries included Approximately 100 hours operation from each new set of batteries Water Tightness Meets or exceeds IP65 standards YSI Incorporated 85 Service Manual 2 Introduction Section 1 Extensive testing of the YSI
6. let it up the light goes out to preserve battery life 3 5 SAVING amp RECALLING DATA The Model 85 is equipped with a non volatile memory that is capable of storing up to 50 different sets of readings Non volatile memory will retain data even if power is lost The Model 85 will also assign a site identity number to each set of readings to allow easy review of the data SAVING DATA TO MEMORY 1 While any parameter is displayed on the screen depress the ENTER button and hold for approximately 2 seconds The meter will flash SAVE on the display along with the current site identity being used 2 When all 50 sites are full the display will flash FULL on the screen This message will remain on the screen even after power down until a button is pushed Once you have acknowledged the memory is full any subsequent saved data will begin overwriting existing data starting with site 1 RECALLING SIORED DATA YSI Incorporated 85 Service Manual 13 System Setup and Operation Section 3 1 To put the Model 85 into the RECALL mode depress the MODE button repeatedly until rel is displayed on the screen along with the site ID number in the lower right corner See figure 1 2 Depress the ENTER button to review the last set of data that was saved The Model 85 will display the dissolved oxygen in saturation and temperature Another press of the ENTER button will display the dissolved oxygen in mg L and the temperature Depress t
7. 0 Troubleshooting and Maintenance Section 4 Electrode Cleaning Model 85 dissolved oxygen probes should be cleaned only when erratic readings occur or after about every 500 hours of use two months Each cleaning removes material and reduces the life of the probe so excessive cleaning should be avoided Gold Cathode For correct probe operation the gold cathode must be textured properly It can become tarnished or plated with silver after extended use Using the adhesive backed sanding disc provided in the 5906 Membrane Kit can clean the gold cathode Stick the disc to a small flat object like a bottle cap then sand the gold with a twisting motion about 3 times or until all silver deposits are removed and the gold appears to have a matte finish If the cathode remains tarnished return the probe for service Silver Anode It is normal for a dark layer of silver chloride to cover the silver anode After prolonged use it may become necessary to clean the anode Soak the probe in a 14 ammonium hydroxide solution for 2 to 3 minutes or overnight in a 3 ammonium hydroxide solution Rinse with deionized water recharge with electrolyte and install a new membrane 4 3 SYSTEM FUNCTIONALITY TEST OXYGEN Functionality of the Model 85 s oxygen system can easily be tested using the following procedure If necessary service the probe s electrodes Follow the instructions in the Maintenance Section Install a fresh membrane and solution
8. 387 Phone 937 767 72419 E Mail info ysi com Lynchford House Lynchford Lane Farnborough Hampshire GUI46LT gt Phone 44 1252 514711 Fax 44 1252 511855 Tix 858210 Sakura Building 6 5 6 13 Shinjuku Shinjuku ku Tokyo 160 Phone 81 3 5360 3561 Fax 81 3 5360 3565 SPECIALTY SERVICE CENTERS Aquaculture Aquatic Eco Systems Inc 1767 Benbow Court Apopka Florida Phone 407 886 3939 Fax 407 886 6787 Aquacenter 166 Seven Oaks Road Leland Mississippi 38756 Phone 601 378 2861 Fax 601 378 2862 Wastewater Q C Services P O Box 68 Harrison 04040 Phone 207 583 2980 Q C Services P O Box 14831 Portland Oregon 97293 Phone 503 236 2712 YSI Incorporated 85 Service Manual 35 Warranty Repair YSI Incorporated 85 Service Manual Section 7 36 APPENDIX A ACCESSORIES AND REPLACEMENT PARTS The following parts and accessories are available from YSI or any YSI Franchise Dealer 030156 Main Board Assembly CE w o Display 030898 Display Assembly CE versions Accessories and Replacement Parts YSI Incorporated 85 Service Manual Appendix A 38 APPENDIX TEMPERATURE CORRECTION DATA FOR TYPICAL SOLUTIONS A Potassium Chloride KCl Concentration 1 mole liter Concentration 1 x 107 mole liter BG FO oO Concentration 1 x 10 mole liter Concentration 1 x 10 m
9. ID s will be erased completely and will be lost forever Do not use the erase function until all recorded data has been transcribed to an archive outside the Model 85 YSI Incorporated 85 Service Manual Figure 2 Section 3 15 System Setup and Operation YSI Incorporated 85 Service Manual Section 3 16 SECTION 4 TROUBLESHOOTING AND MAINTENANCE 4 1 DISCUSSION OF MEASUREMENT ERRORS DISSOLVED OXYGEN MEASUREMENT ERRORS There are three basic types of error Type 1 errors are related to limitations of instrument design and tolerances of instrument components These are chiefly the meter linearity and the resistor tolerances Type 2 errors are due to basic probe accuracy tolerances chiefly background signal probe linearity and variations in membrane temperature coefficient Type 3 errors are related to the operator s ability to determine the conditions at the time of calibration If calibration is performed against more accurately known conditions type 3 errors are appropriately reduced The sample calculations that follow are for a near extreme set of conditions TYPE 1 ERRORS A Meter linearity error 1 of full scale reading or 0 15 mg l B Component and circuitry error 0 05 mg l TYPE 2 ERRORS A Temperature compensation for membrane temperature coefficient 30 03 mg l B Temperature measurement errors A maximum 0 2 C probe error is equal to 0 14 mg l TYPE 3 ERRORS A Altitude 1000 foot change in
10. Manual 12 System Setup and Operation Section 3 AUTORANGING amp RANGE SEARCHING The YSI Model 85 15 an autoranging instrument This means that regardless of the conductivity or salinity of the solution within the specifications of the instrument all you need to do to get the most accurate reading is to put the probe in the sample When you first place the Model 85 probe into a sample or calibration solution and again when you first remove the probe the instrument will go into range search mode that may take as long as 5 seconds During some range searches the instrument display will flash rA NG to indicate its movement from one range to another The length of the range search depends on the number of ranges that must be searched in order to find the correct range for the sample During the range search the instrument will appear to freeze on a given reading for a few seconds then once the range is located will pinpoint the exact reading on the display The display may also switch to 00 0 for a second or two during a range search before it selects the proper range THE BACKLIGHT At times it may be necessary to take measurements with the M ode 85 in dark or poorly lit areas To help in this situation the M odel 85 comes equipped with a backlight that will illuminate the display so that it can be easily read To activatethe backlight press and hold the LIGHT button The display will remain lit as long as the button is depressed When you
11. Model 85 indicates the following typical performance Conductivity 5 FS FS FS 5 FS Dissolved Oxygen 2 Air Saturation I I I 5 5 5 5 I 11 Adjustable Conductivity Reference Temperature 15 C to 25 C Adjustable Temperature Compensation Factor for Conductivity 0 to 4 Temperature Compensation Automatic Range User selected or Autoranging for Conductivity YSI Incorporated 85 Service Manual 3 Introduction Section 1 YSI Incorporated 85 Service Manual 4 SECTION 2 PRINCIPLES OF OPERATION The dissolved oxygen sensor utilizes an oxygen permeable membrane that covers an electrolytic cell consisting of a gold cathode and a porous silver anode This membrane acts as a diffusion barrier and an isolation barrier preventing fouling of the cathode surface by impurities in the environment Upon entering the cell through the membrane oxygen is reduced at an applied potential of 0 8 V referenced to the silver electrode The reduction current at the cathode is directly proportional to the partial pressure of oxygen in liquid expressed as saturation which is proportional to the concentration of dissolved oxygen in mg L at a particular temperature Thus the same partial pressure of oxygen air saturation in liquid gives different concentrations of dissolved oxygen mg L at different temperatures because of the different solubility s of oxygen at different temperatures The conductivity cell u
12. Press release the DOWN ARROW and the M ODE buttons at the same time The CAL symbol will appear at the bottom left of the display 4 Thelarge portion of the display will show 1 91 or a value set previously using Advanced Setup 5 UsetheUp or Down arrow keys to change the value to the desired new temperature coefficient 6 Pressthe ENTER button Theword SAVE will flash across the display for a second to indicate that your change has been accepted 7 Press the MODE button to return to normal operation the CAL symbol will disappear from the display CHANGING THE REFERENCE TEM PERA TURE 1 Turn the instrument on and wait for it to complete its self test procedure 2 UsetheMODE button to advance the instrument to display conductivity 3 Press release the DOWN ARROW and the M ODE button at the same ti me 4 TheCAL symbol will appear at the bottom left of the display Thelarge portion of the display will show 1 9196 or a value set previously using A dvanced Setup Press and release the MODE button the large portion of the display will show 25 06 or a valueset previously using the Advanced Setup 7 UsetheUP or Down arrow keysto changethe valueto the desired new reference temperature any value between 15 and 25 is acceptable 8 Pressthe ENTER button The word SAVE will flash across the display for a second to indicate that your change has been accepted 9 Theinstrument will automatically return to n
13. R YSI Model 85 Handheld Meters are warranted for two years from date of purchase by the end user against defects in materials and workmanship YSI Model 85 probes and cables are warranted for one year from date of purchase by the end user against defects in material and workmanship Within the watranty period YSI will repair or replace at its sole discretion free of charge any product that YSI determines to be covered by this warranty To exercise this warranty write or call your local YSI representative or contact YSI Customer Service in Yellow Springs Ohio Send the product and proof of purchase transportation prepaid to the Authorized Service Center selected by YSI Repair or replacement will be made and the product returned transportation prepaid Repaired or replaced products are warranted for the balance of the original warranty period or at least 90 days from date of repair or replacement Limitation of Warranty This Warranty does not apply to any 51 product damage or failure caused by i failure to install operate or use the product accordance with YSI s written instructions ii abuse or misuse of the product iii failure to maintain the product in accordance with 515 written instructions or standard industry procedure iv any improper repairs to the product v use by you of defective or improper components or parts in servicing or repairing the product or vi modification of the product in any way not expressly
14. TENANCE AND SIORAGE Membrane life depends on usage Membranes will last a long time if installed properly and treated with care Erratic readings can be a result of loose wrinkled damaged or fouled membranes or from large more than 1 8 diameter bubbles in the electrolyte reservoir If erratic readings or evidence of membrane damage occurs you should replace the membrane and the solution The average replacement interval is two to four weeks Precautions If the membrane is coated with oxygen consuming e g bacteria or oxygen evolving organisms e g algae erroneous readings may occur Chlorine sulfur dioxide nitric oxide and nitrous oxide can affect readings by behaving like oxygen at the probe If you suspect erroneous readings it may be necessary to determine if these gases are the cause Avoid any environment that contains substances that may attack the probe materials Some of these substances are concentrated acids caustics and strong solvents The probe materials that come in contact with the sample include FEP Teflon stainless steel epoxy polyetherimide and the polyurethane cable covering Maintenance Probes that have been exposed to hydrogen sulfide or sulfur dioxide for extended periods may cease operating in a normal mode Output current will decrease and may become unstable Visual symptoms include blackening of the silver anode and or discoloration of the gold cathode YSI Incorporated 85 Service Manual 2
15. When you turn the Model 85 off it will remember which mode you used last and will return to that modethe next time the instrument is turned on To choose one of the measurement modes above temperature is always displayed simply press and release the MODE button Carefully observethe small legends at thefar right side of the LCD Specific Conductance Salinity with with 0 Dissolved Oxygen Dissolved Oxygen Conductivity with in 96 with 9 in mg L with C If the instrument is reading Specific Conductance the large numbers on the display will be followed by either aS an mS Additionally the small portion of the display will show thee flashing on and off If theinstrument is reading Conductivity not temperature compensated the large numbers on the display will befollowed by either a 15 or an mS Additionally the small portion of the display will show the C NOT flashing If theinstrument is reading Dissolved Oxygen the large numbers on either a mg L or 96 will follow the display It is important to remember that the dissolved oxygen probe is stirring dependent This is due to the consumption of oxygen at the sensor tip during measurement When taking dissolved oxygen measurements the probe must be moved through the sample at a rate of 1 foot per second to provide adequate stirring If theinstrument is reading Salinity thelarge numbers on the display will befollowed by a ppt YSI Incorporated 85 Service
16. YSI incorporated YSI Model 85 Handheld Oxygen Conductivity Salinity And Temperature System Service 5 SECTION T INTRODUCTION 1 INE Ouucdunl dg 2 1 2 2 SECTION 2 PRINCIPLES 5 SECTION 3 SYSTEM SETUP AND OPERATION cesse eee eren ette seen setas stone setas tease tasca 7 3 1 Preparing the DO Prope 7 3 2 System 8 3 3 Advanced Conductivity 5 10 3 4 Making Measurements 11 3 5 Savins amp v ai ERE 13 SECTION 4 TROUBLESHOOTING AND 17 4 1 Discussion of Measurement Errors 17 4 2 Probe Maintenance 19 4 3 System Functionality Test sicscscciissieseveessevtissvcovsvsvscssessessesenssencesvenenesovsnsvonsicendesstooncssnaeseds 21 4 4 0 22 4 5 TD P 25 SECTION 5 SERVICE 5 1 Disassembly 27 5 2 PCB Assembly Drawittgs 28 5 9 PCB Components vaca vs GM saw esas 29 5 4 Schematic 30 5 5 Exploded
17. al media is usually not known itis best to report conductivity ata particular temperature e g 20 2 mS cm at 14 C However in many cases it is also useful to compensate for the temperature dependence in order to determine at a glance if gross changes are occurring in the ionic content of the medium over time For this reason the M odel 85 software also allows the user to output conductivity data in either raw or temperature compensated form If Conductivity is selected values of conductivity that are NOT compensated for temperature are output to the display If Specific Conductance is selected the Model 85 uses the temperature and raw conductivity values associated with each determination to generate a specific conductance value compensated to a user selected reference temperature see Section 3 3 A dvanced Setup between 15 C and 25 C Additionally the user can select any temperature coefficient from 0 to 4 see Section 3 3 Advanced Setup Using the M odel 85 default reference temperature and temperature coefficient 25 C and 1 91 the calculation is carried out as in equation 1 below Specific Conductance 25 C Conductivity 1 TC T 25 Principles of Operation Section 2 As noted above unless the solution being measured consists of pure in water this temperature compensated value will be somewhat inaccurate but the equation with a value of TC 0 0191 will provide a close approximation for solutions of many common s
18. altitude is equal to an error of approximately 3 at the 10 mg l level B Humidity Errors occur if calibration is performed at less than 10096 humidity The error varies with the temperature as follows TEMPERATURE ERROR 0 0 02 mg l OTE me 027 me Troubleshooting and Maintenance Section 4 APPROXIMATING THE ERROR It is unlikely that the actual error in any measurement will be the maximum possible error A better error approximation is obtained using a root mean squared r m s calculation r m s Error 1a 1b 2a 25 3b mg l CONDUCTIVITY MEASUREMENT ERRO RS System accuracy for conductivity measurements is equal to the sum of the errors contributed by the environment and the various components of the measurement setup These include Instrument accuracy Cell constant error Solution temperature offset Cell contamination including air bubbles Electrical noise Galvanic effects Only the first three are of major concern for typical measurements although the user should also be careful to see that cells are clean and maintained in good condition at all times Instrument Accuracy 5 maximum The accuracy specified for the range being used is the worst case instrument error Cell Constant Error 5 maximum Although YSI cells are warranted to be accurate to within one percent you should still determine the exact cell constant of your particular cell
19. alts such as NaCl and for seawater Salinity is determined automatically from the Model 85 conductivity readings according to algorithms found in Standard Methods for the Examination of Water and Wastewater ed 1989 The use of the Practical Salinity Scale results in values that are unitless since the measurements are carried out in reference to the conductivity of standard seawater at 15 C However the unitless salinity values are very close to those determined by the previously used method where the mass of dissolved salts in a given mass of water parts per thousand was reported Hence the designation ppt 15 reported by the instrument to provide a more conventional output For further information on conductivity and the above standard information refer to the ASTM document Standard Methods of Test for Electrical Conductivity of Water and Industrial Wastewater ASTM Designation D1125 82 and OIML Recommendation Number 56 ASTM symbols for conductivity cell constant and path lengths differ from those preferred in the general literature and also from those used in this manual YSI Incorporated 85 Service Manual 6 SECTION 3 SYSTEM SETUP AND OPERATION 3 1 PREPARING THE DO PROBE DISSOLVED OXYGEN PROBE PREPARATION Follow the instructions below to install fresh solution and anew membrane Unscrew the probe sensor guard Remove the old membrane cap Thoroughly rinse sensor tip with distilled wa
20. authorized by YSI THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE YSI s LIABILITY UNDER THIS WARRANTY IS LIMITED TO REPAIR OR REPLACEMENT OF THE PRODUCT AND THIS SHALL BE YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY DEFECTIVE PRODUCT COVERED BY THIS WARRANTY IN NO EVENT SHALL YSI BE LIABLE FOR ANY SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM ANY DEFECTIVE PRODUCT COVERED BY THIS WARRANTY Warranty and Repair Section 7 AUTHORIZED U S SERVICE CENTERS NORTH REGION EASTREGION YSI Incorporated Repair Center 1725 Brannum Lane Yellow Springs Ohio 45387 Phone 937 767 7241 800 897 4151 Fax 937 767 9353 E Mail ysi info com SOUTH REGION Lynch amp Associates 212 E 2nd Street Suite 203 Pass Christian Mississippi 39571 Phone 800 333 2252 228 452 4612 Fax 228 452 2563 WEST REGION EnviroServices amp Repair 1110 Burnett Avenue Suite D Concord CA 94520 Phone 800 550 5875 Fax 510 674 8655 North Dakota Was hingion South Dakota E Idaho Wyoring i Nebraska Nevada Utah Calforria Arizona YSI Incorporated 85 Service Manual 34 Warranty and Repair Section 7 INTERNA TIONAL SERVIC E CENTERS YSI Incorporated 9 Repair Center 1725 Brannum Lane Yellow Springs Ohio 45
21. ctrodes with Thermistor distilled water In addition it may be necessary to Green S1 Sense clean the conductivity electrodes as described in Red D1 Drive Section 4 Troubleshooting and Maintenance of White D2 Drive this manual Then thoroughly dry the sensor end Black S2 Sense inside and outside and with compressed air or a Blue Thermistor soft towel before testing Caution The probe must be clean and dry to perform this test External contamination of the probe may give a false defective indication Brown Thermistor Orange Anode Shielded White Cathode Shield Drain No connection Use the probe wiring chart to confirm that the resistance between all of the electrodes except when measuring between the two thermistor leads is greater than 200 megaohms Continuity less than 200 megaohm indicates an internal electrical short which will require probe replacement YSI Incorporated 85 Service Manual 24 Troubleshooting and Maintenance Section 4 4 5 TROUBLESHOOTING SYMPTOM POSSIBLE CAUSE ACTION 1 Instrument will not turn on A Low battery voltage A Replace batteries B Batteries installed wrong B Check battery polarity C Power supply circuit defect C Troubleshoot circuit Replace PC board 2 Instrument will not calibrate A Membrane is fouled or damaged A Replace membrane amp Dissolved Oxygen B Probe anode is fouled or dark B Clean anode C Probe cathode is tarnished C Clean cathode D Circuit or probe fai
22. ease or decrease the altitude When the proper altitude appears on the LCD press the ENTER button once EXAMPLE Entering the number 12 here indicates 1200 feet 5 The 85 should now display CAL in the lower left of the display the calibration should be displayed in the lower right of the display and the actual should be on the main display Press the ENTER button and the display should read SAVE then should return to the Normal Operation Mode Each time the M 85 is turned off it may be necessary to re calibrate before taking measurements All calibrations should be completed at a temperature which is as close as possible to the sample temperature Dissolved oxygen readings are only as good as the calibration YSI Incorporated 85 Service Manual 8 System Setup and Operation Section 3 CAUBRA TION OF CONDUCTIVITY IMPORTANT System calibration is rarely required because the YSI Model 85 conductivity cell is typically very stable H owever after service it is wise to check the system calibration and make adjustments when necessary Prior to calibration it is important to remember the following Always use clean properly stored NIST traceable calibration solutions See A ccessories and Replacement Parts and a clean calibration container Rinse the probe with distilled water and wipe dry between changes of calibration solutions When placed in solution allow the probe time to stabilize with regard to temperat
23. he ENTER button again and again to review the conductivity specific conductivity and salinity readings All of which are displayed with the 0 1 temperature Figure 1 3 Depress the UP ARROW button to increment through the saved sets of data 4 Depress the DOWN ARROW button to decrement through the saved sets of data NOTE The Model 85 will recall data as a list When the UP ARROW is depressed the Model 85 will display the Site ID for the previously recorded date For example If you are reviewing Site ID 5 and the UP ARROW is depressed the Model 85 will display Site ID 4 If you reviewing Site ID 5 and Site ID 5 was the last set of data stored the DOWN ARROW button will display Site ID 1 Here is an example of the Model 85 memory Site ID 1 Site ID 2 Site ID 3 If the UP ARROW button was pressed the Model 85 would display Site ID 2 Site ID 4 Site ID 5 ERASING STORED DATA 1 To erase the data that is stored into the Model 85 s memory depress the MODE button repeatedly until the Model 85 displays ErAS on the screen See figure 2 YSI Incorporated 85 Service Manual 14 System Setup and Operation 2 Depress and hold the DOWN ARROW and ENTER buttons simultaneously for approximately 5 seconds 3 The Model 85 flashing DONE on the display for 1 to 2 seconds indicates successful erasure The instrument will automatically change to normal operation after completion IMPORTANT Data in 50 site
24. ion container and its proximity to external objects to the minor galvanic effects resulting from oxide formation or deposition on electrodes Only trial and error in the actual measurement environment can be suggested as an approach to reduce such errors If the reading does not change as the setup is adjusted errors due to such factors can be considered too small to see 42 PROBEMAINTENANCE CONDUCTIVITY CELL CLEANING AND STORAGE The single most important requirement for accurate and reproducible results in conductivity measurement is a clean cell A dirty cell will change the conductivity of a solution by contaminating it When in use the cell should be rinsed with clean water after each use YSI Incorporated 85 Service Manual 19 Troubleshooting and Maintenance Section 4 To clean the conductivity cell 1 Dip the cell in cleaning solution and agitate for two to three minutes Any one of the foaming acid tile cleaners such as Dow Chemical Bathroom Cleaner will clean the cell adequately When a stronger cleaning preparation is required use a solution of 1 1 isopropyl alcohol and 10N Remove the cell from the cleaning solution 2 Use the nylon brush supplied to dislodge any contaminants from inside the electrode chamber 3 Repeat steps one and two until the cell is completely clean Rinse the cell thoroughly in deionized or clean tap water 4 Store the conductivity cell in the meter storage chamber OXYGEN PROBE MAIN
25. lure D Replace defective assembly 3 Instrument will not calibrate A Cell is contaminated A See Maintenance Chapter Conductivity 4 Instrument locks up A Instrument has rec d a shock A amp B Remove battery lid wait 15 B Batteries are low or damaged seconds for reset replace lid C Defective main PC board C Replace main PC board 5 Instrument readings are inaccurate A Cal altitude is incorrect A Recalibrate w correct value Dissolved Oxygen Probe not in 100 saturated air B Moisten sponge amp place in Cal during Cal procedure chamber w probe amp Recal C Membrane fouled or damaged C Replace membrane D Probe anode is fouled or dark D Clean anode E Probe cathode is tarnished E Clean cathode System requires service Return system for service 6 Instrument readings are inaccurate A Calibration is required A See Calibration Chapter Conductivity B Cell is contaminated B See Maintenance Chapter C Tempco is set incorrectly C See Advanced Setup Chapter D Reference temperature incorrect D See Advanced Setup Chapter E Readings are or are not temperature E See Making Measurements compensated Chapter A Batteries are defective or have been A Replace batteries 7 LCD displays LO BAT installed incorrectly B Replace PCB B Defective main or display PCB 8 Main Display reads OVEr A Conductivity reading is 2200 mS In all cases check calibration values
26. ndard 4 4 TESTPROCEDURES As stated in the Section 1 1 Service Philosophy of this manual the best way to troubleshoot the M 85 is by substitution Below are procedures to test the accuracy and function of theinstrument s circuits and probe If any section of the tests fail the board assembly or probe will have to be repaired or replaced When disassembled connecting a jumper wire to the DGNG pin of and momentarily touching the desired pin or pins can simulate the instrument s keypad functions CONDUCTIVITY AND TEMPERATURE CIRCUIT TEST 1 Disassemble the instrument case by referring to Section 5 1 Disassembly Procedures section of this manual Drive 1 2 Once the 85 probe is unplugged from Decade PCB connector JP1 connect a decade TE Resistance resistance box in its place Reference Sense 2 Box Figure 1and Figure 2 Drive 2 3 Use either a second decade resistance box or a 10K ohm resistor to RTI substitute for the thermistor RT1 and RT2 RT2 This resistance must be substituted or an error we displayed on the LCD Model 85 Test Cable 4 Using Section 3 2 System Calibration Simulators procedure start at step 7 calibrate to 450 0 15 using inputs of 11 11 at 1 10 00 KQ at R2 Figure 1 5 Use the charts below to test the instrument s accuracy Also check the cell constant by cycling the instrument on an off It should fall between K 4 90 and 5 10 In chart 1 the t
27. of actual circuits PCB A wo 57 VC E same rasp Ium 10k 09 014 IN9 14 SH 3 SH 3 YSI Incorporated 85 Service Manual 30 Section 5 ee H 12242544540 AQ 1 6 ANSEL gt E SDA gt 4 4 1 43 2515 5 4 CENT IGRADE SHOWN FAHRENHEIT SUPPRESS PCB B j BATTERY BACKLIGHT 5 too Roy too we LEG PSI AH RUN ibi im im 4 PN 7 14 225 EE 2 YSI Incorporated 85 Service Manual 31 5 5 EXPLODED VIEW Section 5 Bubble Number YSI Order Number 038501 055242 038502 030156 030898 055204 055244 118510 118522 118527 118519 BWW WN Description Front Case Assy W Keypad Rear Case Assy Board Assy Main Non CE Board Assy Main CE w Display Board Assy Display CE Kit Case Hardware Kit Battery Hardware Probe amp Cable Assy 10 feet Probe amp Cable Assy 25 feet Probe amp Cable Assy 50 feet Probe amp Cable Assy 100 feet YSI Incorporated 85 Service Manual 32 SECTION 6 WARRANTY AND REPAI
28. ole liter 97000270 Charts developed by interpolating data from nternational Critical Tables Vol 6 229 253 McGraw Hill Book Co NY Temperature Correction Data Appendix B B Sodium Chloride NaCl Saturated solutions at all temperatures Concentration 0 5 mole liter 97009270 Concentration 1 x 107 mole liter Concentration 1 x 10 mole liter 97000270 97019270 Concentration 1 x 10 mole liter TEE Charts developed by interpolating data from the CRC Handbook of Chemistry and Physics 42nd ed p 2606 The Chemical Rubber Company Cleveland YSI Incorporated 85 Service Manual 40 APPENDIX VALUES TABLE Table A Calibration values for various atmospheric pressures and altitudes Note This table is for your information only It is not required for calibration Calibration Values Table Appendix B 20 35 10293 3137 1 6 YSI Incorporated 85 Service Manual 42 Calibration Values Table YSI Incorporated 85 Service Manual Appendix B 43 Calibration Values Table Appendix B YSI Incorporated 85 Service Manual 44 YSI incorporated 1725 Brannum Lane Yellow Springs Ohio 45387 800 897 4151 937 767 7241 FAX 937 767 9353 E mail Info YSI com Website http www Y SI com Item 038504 DRW A38504B May 1998
29. olerance column reflects the accuracy of the decade resistance box YSI Incorporated 85 Service Manual 22 Troubleshooting and Maintenance Section 4 Conductivity Test Chart 1 Decade Tolerance Nominal Reading Acceptable Reading 33 330 10 00 1 150 0 mS 147 2 to 152 8 mS 111 10Q 10 00 1 45 00 mS 44 37 to 45 65 mS 1111 0 Q 10 00 1 4 500 mS 4442 to 4560 uS 11 11 KQ 10 00 1 450 0 uS 450 0 uS Note After the above procedure is used it will be necessary to recalibrate the system See System Calibration Temperature Test Chart 2 0 0 1 C 0 1 Pin out JP1 51 52 RT2 6 DI D2 PCB End Bottom Figure 2 DISSOLVED OXYGEN CIRCUIT TEST Perform this test using a YSI 16423 Oxygen Test Box or by inputting the resistance values in column 2 To begin the test input the resistance valuein Row 1 or set the test box to A 2 and calibrate the 100 0 If using the resistances from column 2 maintain the temperature at 10 0 from Chart 2 above Input to connector J6 Pins 1 amp 2 Set 16423 Test Resistor input Display Reading Display Reading YSI Incorporated 85 Service Manual 23 Troubleshooting and Maintenance Section 4 PROBE LEAKAGE TEST Electrical leakage between the probe s electrodes Model 85 Probe Wiring Chart can cause system failures Remove the probe s Probe Wire Color Electrode or oxygen membrane and rinse the ele
30. ormal operation mode CHANGING FROM AUTORANGING MANUAL YSI Incorporated 85 Service Manual 10 System Setup and Operation Section 3 If your application is easier to perform using a manual range that you select the Y SI Model 85 allows you to turn off the default autoranging feature While you are making conductivity or temperature compensated conductivity measurements simply press and release the UP ARROW button Each additional press of the UP ARROW button will cyclethe M odel 85to a different manual range until you return again to autoranging Five pushes of the UP ARROW button will cycle the M 85 through the four manual ranges and return the instrument to autoranging NOTE You may seean error message in some manual ranges if the manual range selected is not adequatefor the sample you are measuring If this happens simply press and releasethe UP ARROW button again until a rangeis selected which is suitablefor your sample If you get lost and don t know if you rein a manual range or autoranging simply turn the instrument off and back on Also note that the conductivity units will flash while you in manual range Theinstrument will always default to autoranging when first turned on The four ranges of the YSI Model 85 are 3 4 MAKING MEASUREMENTS TURNING THE INSTRUMENTON Oncethe batteries are installed correctly turn the instrument face up and press the ON OFF button Theinstrument will activate all
31. relief Pull straight up on the battery chamber to separate the case halves Unplug the power connector from the PC Board NOTE Because the Model 85 is water tight the case halves will be relatively difficult to separate STEP 4 The main PC Board is held in place by a single Phillips screw located in the center of the board Remove the screw and gently pull the PC Board away from the front case NOTE The leads on the cable that connect to the main PC Board are quite short Be careful not to damage the terminal connectors when you pull the PC Board away from the front case STEP 5 Carefully slide the probe cable terminal connector out of its mating connector Make note of the wire color configuration so that the connectors can be correctly re installed later STEP 6 To separate the probe cable from the front case unscrew the outer portion of the strain relief that portion which does not make contact with the front case Slide the spiral portion of the strain relief down the cable toward the probe Next unscrew the remaining portion of the strain relief from the front case STEP 7 To separate the LCD from the main PC Board squeeze the four plastic offset spacers and slide the LCD PC board away from the main board one corner at a time Next remove the four small Phillips screws from the back of the LCD and remove the LCD from its clear plastic frame STEP 8 To remove the keypad from the front case use a small Phillips scre
32. segments of the display for a few seconds which will befollowed by a self test procedure that will last for several more seconds During this power on self test sequence the instrument s microprocessor is verifying that the instrument is working properly The Model 85 will display the cell constant of the conductivity probe when the self test is complete If the instrument wereto detect an internal problem the display would show a continuous error message on the display You can discover the meaning of these error messages by referring to Section 4 5 Troubleshooting YSI Incorporated 85 Service Manual 11 System Setup and Operation Section 3 THE MEASUREMENT MODES OF THE MO DEL 85 TheModel 85 is designed to provide six distinct measurements gt Dissolved Oxygen A measurement of oxygen in percent of saturation Dissolved Oxygen mg L A measurement of oxygen in mg L gt Conductivity A measurement of the conductive material in the liquid sample without regard to temperature Specific Conductance Also known as temperature compensated conductivity which automatically adjusts the reading to a calculated value which would have been read if the sample had been at 25 C or some other reference temperature which you choose See dvanced Setup Temperature which is always displayed gt Salinity A calculation done by the instrument electronics based upon the conductivity and temperature readings NOTE
33. self diagnostic routine each time the instrument is turned on The self diagnostic routine provides you with useful information about the conductivity cell constant and function of the instrument circuitry The system simultaneously displays temperature in C along with one of the following parameters dissolved oxygen in either mg L milligrams per liter or air saturation conductivity temperature compensated conductivity 5 mS cm and salinity in parts per thousand ppt The system requires only a single calibration regardless of which dissolved oxygen display you use The calibration of conductivity is not required but is available A single calibration will adjust the instrument regardless if you are reading conductivity or temperature compensated conductivity You can switch between all of these parameters with the push of a single key Six AA size alkaline batteries power the instrument A new set of alkaline batteries will provide approximately 100 hours of continuous operation When batteries need to be replaced the LCD will display a LO BAT message Introduction Section 1 11 SERVICE PHILOSOPHY The YSI Model 85 is sold as a complete dissolved oxygen conductivity and salinity measuring system including an attached probe Most service issues that occur in dissolved oxygen and conductivity systems are caused by improper maintenance of the probe For this reason troubleshooting efforts should be initially
34. stant cal mode temperature exceeds the values computed using user defined temperature coefficient and or reference temperature 13 Main display reads Err A System has failed its RAM test A Turn instrument OFF and back ON Secondary display reads check procedure again B Replace main PCB 14 Main display reads Err A System has failed its ROM test A Turn instrument OFF and back ON Secondary display reads ro check procedure again B Replace Main PCB reading is gt 199 9 F but lt 203 F Defective main PCB or probe Secondary display reads time Replace main PCB 17 Readings on main display don t A Meter is in recall mode A Press MODE button to return to change Normal Operation YSI Incorporated 85 Service Manual 26 SECTION 5 SERVICE 5 1 DISASSEMBLY PROCEDURES Refer to the Assembly drawing on the next page before attempting to disassemble the meter case Follow these steps to disassemble the meter case STEP 1 Place the instrument face down on a flat cloth covered surface Use a Phillips screwdriver to completely remove the screw located at the bottom of the hand strap STEP 2 Using a standard screwdriver or a small coin loosen the battery lid screw and remove the battery lid and all six AA size batteries STEP 3 With the instrument face down on the flat cloth covered surface place two fingers into the battery chamber and your other hand over the cable strain
35. ter Inspect the gold electrode and silver electrodes If resurfacing is required refer to Section 4 2 Probe Maintenance 5 Prepare the electrolyte according to the directions on the KCI solution bottle 6 Hold the membrane cap and fill it at least 1 2 full with the electrolyte solution 7 Screw the membrane cap onto the probe moderately tight A small amount of electrolyte should overflow Fill Membrane with KCL Solution Unscrew Cap Unscrew Guard CC Screw Screw Guard on moderately tight moderately tight System Setup and Operation Section 3 3 2 SYSTEM CALIBRATION CAUBRATION OF DISSOLVED OXYGEN To accurately calibrate the YSI 85 you will need to know the approximate altitude of the region in which you plan to take your dissolved oxygen measurements 1 Ensure that the sponge inside the instrument s calibration chamber is wet Insert the probe into the calibration chamber 2 Turn the instrument on by pressing the ON OFF button on the front of the instrument Press the MODE button until the dissolved oxygen is displayed in mg L or Wait for the dissolved oxygen and temperature readings to stabilize usually 15 minutes is required 3 Use two fingers to press and release the UP ARROW and DOWN ARROW buttons at the same time once 4 The LCD will prompt you to enter the local altitude in hundreds of feet Use the arrow keys to incr
36. tilizes four pure nickel electrodes for the measurement of solution conductance Two of the electrodes are current driven and two are used to measure the voltage drop The measured voltage drop is then converted into a conductance value in milli Siemens millimhos To convert this value to a conductivity specific conductance value in milli Siemens mS the conductance is multiplied by the cell constant that has units of reciprocal cm cm 1 The cell constant for the Model 85 conductivity cell is 5 0 4 For most applications the cell constant is automatically determined or confirmed with each deployment of the system when the calibration procedure is followed Solutions with conductivity s of 1 00 10 0 50 0 and 100 0 mS cm which have been prepared in accordance with recommendation 56 1981 of the Organization International De Metrologie Legale OIM L are available from YSI Theinstrument output is in WS or mS cm for both conductivity and specific conductance The multiplication of cell constant times conductance is carried out automatically by the software TEMPERA TURES EFFECT ON CONDUCTIVITY The conductivity of solutions of ionic species is highly dependent on temperature varying as much as 3 for each change of one degree Celsius temperature coefficient 3 C In addition the temperature coefficient itself varies with the nature of the ionic species present Becausethe exact composition of a natur
37. tly reporting the conductivity seen but the reading does not accurately represent the value of the bulk solution Errors will be most serious when low conductivity solutions are contaminated by carry over from high conductivity solutions and can then be of an order of magnitude or more Follow the cleaning instructions carefully before attempting low conductivity measurements with a cell of unknown history or one that has been previously used in higher value solutions An entirely different form of contamination sometimes occurs due to a buildup of foreign material directly on cell electrodes While rare such deposits have on occasion markedly reduced the effectiveness of the electrodes The result is an erroneously low conductance reading Electrical Noise Errors Electrical noise can be a problem in any measurement range but will contribute the most error and be the most difficult to eliminate when operating in the lowest ranges The noise may be either line conducted or radiated or both and may require grounding shielding or both Galvanic and Miscellaneous Effects In addition to the error sources described above there is another class of contributors that can be ignored for all but the most meticulous of laboratory measurements These errors are always small and are generally completely masked by the error budget for cell constant calibration instrument accuracy etc Examples range from parasitic reactances associated with the solut
38. ure approximately 60 seconds and gently agitate the probe to remove any air bubbles To minimize error perform sensor calibration at a temperature as close to 259 as possible To perform an accurate calibration of the YSI Model 85 1 2 Clean the probe thoroughly see Probe aintenance Place at least 3 4 inches of solution in a clean glass beaker Select a calibration solution which is most similar to the sample being measured For sea water choose a 50mS cm conductivity standard YSI Item 3169 Forfresh water choose a 1mS cm conductivity standard YSI Item 3167 brackish water choose a 10mS cm conductivity standard YSI Catalog 3168 Turn theinstrument on Usethe M ODE button to advancethe instrument to display conductivity Insert the probe into the beaker deep enough to cover the entire probe Do not rest the probe on the bottom of the container suspend it above the bottom at least 1 4 inch Allow at least 60 seconds for the temperature reading to become stable Movetheprobe vigorously from sideto sideto dislodge any air bubbles from the electrodes Press and release the UP ARROW and DOWN ARROW buttons at the sametime The CAL symbol will appear at the bottom left of the display to indicatethat the instrument is now in Calibration mode Usethe up or down arrow key to adjust the reading on the display until it matches the value of the calibration solution you are using Oncethe display reads the exact
39. value of the calibration solution being used the instrument will make the appropriate compensation for temperature variation from 25 C press the ENTER button once The word SAVE will flash across the display for a second indicating that the calibration has been accepted Note The YSI Model 85 is designed to retain its last conductivity calibration permanently Therefore there is no need to calibrate the instrument after battery changes or power down YSI Incorporated 85 Service Manual 9 System Setup and Operation Section 3 3 3 ADVANCED CONDUCTIVITY SETUP The default reference temperature and temperature coefficient setting of the 85 are appropriate for the vast majority of measurement applications However it is important that the service technician understand that the user may have modified these settings and will affect temperature compensated measurements IMPORTANT Thereis never need to enter Advanced Setup Mode unless there 15 a need for changein the reference temperature and or the temperature coefficient Therefore unless you are certain that an application requires a change to one or both of these criteria do not modify the default reference temperature 25 C or the default temperature coefficient 1 91 CHANGING THE TEMPERATURE COEFFICIENT 1 Turn instrument on and wait for it to complete its self test procedure 2 UsetheMODE button to advance the instrument to display conductivity 3
40. wdriver to remove the screws from the keypad s metal backplate then lift the keypad away from the front case Section 5 5 2 PCB ASSEMBLY DRAWINGS 6l a PCB A Main Board Non CE Units YSI 55 C 9207 Y PCB B Display Board PCB C Keypad Board YSI Incorporated 85 Service Manual 28 5 3 PCBCOMPONENTS YSI 85 A BOARD MAIN BARE CONN 6 PIN RT ANGLE CONN 8 PIN WAFER JP3 JP7 JP8 CONN 3 PIN WAFER CONN 5 PIN RT ANGLE i N y R3 25PPM RES 887K 1 1 4W R4 R5 25PPM RES 49 9K 1 1 4W RES 45 3K 1 1 4W RES 4 53 1 1 4W RES 374 1 RES 124 1 5 0 RISRIGRODRCA RITRISROS 8 RES 54 9K 1 1 4W SIE 55 26015 07629554555 ZIR OBO 6 7 10 14 2 MPF 0 1uF 63V 1 23 27 C15 C19 C20 APR MPE 1uF 63V C16 C18 CER 100pF C17 APR MPE 0 33uF 63V C22 CAPR ELE 2 2uF 16V Q Section 5 Circuit Description Qty Symbol UI2 GFneed Dss LED LAMP HIMP 1540 6 MINIJUMPER DS 001 ete YSI Incorporated 85 Service Manual 29 Section 5 5 4 SCHEMATIC DIAGRAMS Schematic diagrams are representative
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