MOTM-850 User Manual
Contents
1. td GNV ANNYIT AG GSNDISSG _ rarr 888 AZT XL HLYOM LAOA 2 A89 Ud ACAIN TIZOG Sz995 Su ADOIONHOAL SISHHLNAS t S i ALYD T 3007 S cea CIOHSHAHL H IIT O ASZ T sD WOT SOT ALS ALZO 92 5 08 EZT Sa ei g aoe AST SC SCD pa DIULS DOOW Z Zar SOd Z T de ZT IG INI AZT V AZT EN AZT INT O AGZ vO WOT Z ED 5 ou TS I Fe AST INT O ZT ISAN I 62 zn AZT T MOOT PAA S s AZT MOT lt PTA WOT WOT anita ETOTLT SE SS SS wen NI XIN zn AST N A ALA AST LAKAAS TI 4LINAAA aZTT Tar T I T sr azee T SI vaqa z LO PZA Te MOT a Sa SC SCH MOT ST edat Se 06ENZ sta TO J HLWD ii TOE a T ozs DIALS JF e x 4 AD L vo Toa ozs LANO AO ST suze AGT we ETOTLI gt pea arn EE LASAAO qur aaa A VHVNWVA Z Ta Tou TTA z ST MOOT GNWIOW Z T MOST MOST 9TA LOd MOOT XOA Mad T V OTA T MOOT 6a AZT ZAA AZT AZT AST R MOTM 85 PEDAL INTERFACE R12 A Q IHLA C gys L A LO di d ACL Jaa 2 J R22 U4 s L Sms a Co ria lt A NO O2. CASE 3 THE GATE BEHAVIOUR IS BACKWARDS In normal operation you trigger the GATE at some point as the pedal is depressed and it stays active until the pedal comes up However if you set RANGE to 5V and OFFSET to 0 so that the module outputs OV to 5V when pressed AND you set GATE to 2 5V the halfway point you will notice the LED is Ht GATE ACTIVE when the pedal is up and turns off as the pedal goes down Why Because when the pedal is up all the way the DC output is OV which EXCEEDS the GATE threshold of 2 5V GATE TYPE SELECTION There are 2 types of GATE signals in electronic synths VTRIG and STRIG STRIG is Moog specific When GATE is INACTIVE the GATE output is 12V When GATE is ACTIVE the GATE output is OV If you are using the MOTM 850 to control a Moog modular Rogue Source MiniMoog or other Moog synth be sure JP2 is set on STRIG VTRIG is the normal setting for MOTM and other synths This is the EXACT OPPOSITE of STRIG VTRIG is OV when inactive and 12V when active That sums up how the module itself functions How it s actually used in your MOTM system is entirely up to your imagination You can use pedals to sweep filters add PWM to VCOs change the LFO rates or any of 100 other functions TROUBLESHOOTING If your MOTM 850 does not work please verify ALL of the following before contacting us The following reference directions assume that you are looking a
3. Solder the coax in J3 to the GATE Jack Solder the orange white gray wire in J1 to the PEDAL jack The Orange wire goes to the BOTTOM lug the White wire goes to the LEFT lug and the gray wire goes to the BEVELED lug Rotate all of the front panel pots fully counter clockwise Locate the KNOBS Notice each knob has a white line on it Place the knob on the pot shaft align the white line to the 0 tick mark and tighten the hex screw The silver part of the knob has a protective clear plastic overlay that can be removed if desired Gently rub with your fingernail across it and it will peel off Use the extra wire tie to bundle the coax wires KEREERREERRERRERRERERERREERRERRERRERERERRERREREERRERRERRERRERRERRRERRERRERRERRERRERRREREE CONGRATULATIONS YOU HAVE FINISHED BUILDING THE MOTM 850 kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk All that s left to do is test it But before we do please read the following Theory of Operation SYNTHESIS TECHNOLOGY PAGE 11 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM THEORY OF OPERATION The MOTM 851 consists of 2 separate circuits the voltage drive to the pedal and the scaling offset and the Gate extractor The MOTM 850 can interface to 2 basic types of pedals resistive and voltage out Resistive pedals use a 3 conductor stereo plug because 3 signals are needed ground voltage IN and voltage OUT CV Out pedals use a 2 conductor plug m
4. and is soldered to the Black wire Insert the LED through the panel with the longer Anode lead towards the top panel edge looking from the rear this is towards the left SYNTHESIS TECHNOLOGY PAGE 10 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM d Press the LED snugly to the panel Now cut off half of the LED s leads they are too long Place the 2 pieces of heat shrink tubing down over the Red Black wires With a pair of chain nosed pliers make a small J hook in each LED lead Then make J hooks on the Red and Black wires Mate the Red wire to the Anode lead and solder Do the same with the Black lead and the Cathode After waiting 20 seconds for cooling slip the heat shrink tubing all the way down until they touch the back of the LED case Use a heat gun on LOW setting to shrink the tubing You can also use the soldering iron hold it very close BUT NOT TOUCHING the tubing Now you will solder to the 4 jacks Each jack has 3 lugs from the rear we will refer to them as LEFT TOP BOTTOM for J1 and BEVELED The TOP lug is for the switched contact this is a NC normally closed contact that 1s opened when a plug is inserted In all 3 cases this lug is NOT USED Solder the coax in J4 to the CV OUT jack The braid goes to the BEVELED lug The inner conductor goes to the LEFT lug This is true of ALL coax wires Use enough solder to completely fill in the hole on the lug Solder the coax in J2 to the MIX IN jack
5. is strictly for use on the pc board and is NOT to be used on the front panel wiring In order for solder to stick to the copper a chemical called flux is embedded in the solder The flux leaves a residue on the pc board that should be cleaned with warm water DO NOT USE SOAP OR OTHER CLEANSERS Most of the parts in the kits are waterproof and can be washed in the sink The flux is OSHA approved for flushing down the drain so don t worry about that A soft brush is used to gently scrub the board We recommend a fingernail brush which is about 1 x 2 and can be found for about 1 The other type of solder is called No Clean Flux because as the name implies it does not require washing This solder is used for wiring the pots switches jacks etc This solder is harder to use on the pc board because even when melted it is not very fluid about the consistency of toothpaste We will use it VERY SPARINGLY on the pc board OK let s get started on the board PART 1 SOLDERING THE RESISTORS Since there are more resistors than anything else we will start here If you do not know the resistor color code refer to the parts list Resistors are not polarity sensitive but the board will be easier to debug and look nicer if you point the first color band in the same direction for all the parts The color code is also in the README FIRST document that every customer receives with his or her first order You will
6. start by soldering in ALL of the resistors J Find the RESISTOR bag Find the MOTM 850 blank pc board There 18 a copy larger than actual size of the silkscreen which shows where the parts go at the end of this document It will be useful if you locate the part on the print first put the part in the board then check off the silkscreen All parts are inserted from the side of the board with the white silkscreen the top side NOTE some reference designators are under the resistor Be careful We will stuff the reslstors by value to make things easier The resistors and other long leaded parts are inserted on a 0 4 inch spacing The important thing is to be sure that the part 1s sitting all the way down on the board Push the leads in the holes push the part on the board and then bend the leads on the bottom outwards to a 45 degree angle roughly This is called cinching the leads and keeps the part from falling out From the bottom of the board solder using the organic flux applying heat to the pad for about a half second first then applying just enough solder to make a small puddle that looks like a tiny pyramid Enough solder should SYNTHESIS TECHNOLOGY PAGE 5 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM d d UU Hu LI UU Hu flow in the hole such that on the top component side a small amount is on the top pad as well There are many 1 resistors in this kit They have light blue body color
7. the rear of the panel Screw by hand each hex nut on the pots so that it 1s all the way on touching the face of the pot Now pick up the pc board bracket assembly and carefully slide lt over the 2 threaded studs making sure the pots are aligned in the holes Use 2 6 KEPS nuts and tighten the bracket to the panel Loosen the 4 KEPS nuts on the bottom of the bracket Slide the pcb ALL THE WAY TO THE RIGHT AS FAR AS IT WILL GO so that the 4 pot nuts are all pressing against the panel By hand put hex nuts on the outside threads of VR1 and VR4 to keep the pc board in place Now tighten the 4 KEPS nuts on the bracket The pcb and bracket should be secure with no gaps visible between the panel and the pot nuts You may need to loosen the nuts on the pots so that they are touching the back of the panel Again make sure each pots nut is touching the back of the panel no gaps There will be a gap from the edge of the pc board to the panel Remove the hex nuts on VR1 amp VR4 For all of the pots first put on the flat washer then the hex nut Tighten with a 2 nut driver PART 9 FINISH WIRING TO THE PANEL Please read the following instructions carefully In order to neatly attach the many wires to the front panel components the wires are soldered in a specific order Find the red LED assembly Note that one lead is slightly longer This is the Anode and it is soldered to the Red wire in D1 The other lead is the Cathode
8. to the left on the scale Is this making ANY sense at all Why am 1 going on and on about this Because you can set the GATE control to not activate all or you may find the GATE is acting backwards than expected Let s go over 3 cases of which 2 are bad CASE 1 EXPECTED BEHAVIOUR Let s use a simple case to start We want the 850 to output 0 to 8V over the pedal range So we set RANGE to 8V and the OFFSET to OV Easy enough Now we have to decide when the GATE triggers Let s pick the point when the pedal is of the way down AND the voltage is of the maximum Hmmmm that s 1 5V So we set the GATE control to 1 5V Hey it works great Just about in the middle of depression the GATE LED lights up and stays lit until the pedal is upwards past the mid point As long as the pedal is down below the halfway point then DC voltage out of the module EXCEEDS 1 5V and GATE is active CASE 2 GATE THRESHOLD IMPROPERLY SET This is an error but an easy one to figure out If in the above example you set GATE to 4V the LED would never come on That tells you the CV out of the module never exceeded the GATE threshold SYNTHESIS TECHNOLOGY PAGE 17 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM Conversely if you set the GATE below 0 then the LED is on ALL THE TIME That is because the pedal output always EXCEEDS the GATE threshold remember OV is bigger than any negative voltage in this circuit
9. wiper of VR1 Since the voltage output from the pedal is not buffered and has a large SYNTHESIS TECHNOLOGY PAGE 14 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM series resistance R24 then enters into the overall transfer function to warp the x 1 x pedal output Rather than go through 5 pages of algebra let it be said this value was picked empirically That is we stuck different values in there until satisfied We may be perfectionists but know the value of a good resistor decade box INTERFACING TO CV OUT PEDALS MODULES The third type of pedal runs off of batteries and outputs a DC voltage directly For these pedal types or to process external voltages such as the output of a MOTM 800 EG the blue jumper shunt is removed from JP3 You can also park the shunt by sticking only one pin of the header into the shunt so the other half of the shunt is sticking out over the pc board See Figure 3 This prevents you from losing the shunt if you change pedal types PARKING THE SHUNT With the shunt removed the additional resistor R16 is added into the series resistance If you have a pedal with a 100K pot this makes the total series resistance 199K so the output voltage is again 0 to 5V Since CV out pedals use mono 2 conductor plugs the ring connection is shorted to ground through R16 R17 R18 This doesn t matter The CV out from the pedal is to the Tip connection which goes str
10. 10 along with some gain provided by the ratio of R21 R11 limit the DC offset to 2 5V Resistors R14 and R19 are used to balance the DC offset voltage at the op amp s and terminals due to input bias currents This greatly reduces DC temperature drift OK that s pretty straightforward but what about resistor R24 What is it doing This is the clever part of the circuit This 18 called a warping resistor because the pedal output is non linear with pedal angle We will talk about this resistor in the next section The Gate extractor is comparator U1 GATE pot VR3 along with resistors R4 and R5 set the trip point to 5V Hysteresis is set by R2 and R6 The width of the hysteresis is set wide about 0 5V on purpose It makes false triggering of the Gate output greatly reduced as you wail away on the pedal If you think it s too wide increase R2 to 560K SYNTHESIS TECHNOLOGY PAGE 12 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM The op amp and comparator are powered off separate 12V supplies by U2 and U3 This is done for several reasons First it provides a load isolated voltage reference for the OFFSET and GATE pots the pedal doesn t need this Second it isolates current spikes from the 15V line as the LED switches on and off The LM311 output is open collector so R3 provides the pullup The GATE signal can be selected to be positive true VTRIG or shorting to ground STRIG Moog uses STRI
11. G everybody else uses VTRIG Jumper JP2 selects which type is outputted to the jack The output of the comparator is a VTRIG rises to 12V when the comparator trips and a simple transistor inverter Q1 R1 R8 provides STRIG Q1 alsoisa free way to drive the GATE LED D1 since we are turning on the LED by shorting it s cathode to ground did I mention how clever we are INTERFACING TO THE ROLAND EV 5 The EV 5 pedal has 2 pots wired in series The pedal mechanism pot is a 10K 20 anda separate offset trimmer pot of 50K See Figure 1 ROLAND EV 5 PEDAL PEDAL gt 10K OFFSET TRIM 0 CONTROL 50K Assuming the trimmer pot is at dial position 0 normal operation the circuit is simple The jumper JP3 is set to feed 15V through R18 16K5 The output is from the wiper and is given by the equation Vout 15 Rdown Rdown 16500 10000 Where 16500 is the value of R18 and 10000 is the value of the pedal pot Rdown is the fractional resistance of the 10K pot as you press down SYNTHESIS TECHNOLOGY PAGE 13 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM From this the maximum voltage out 1s when the pedal is all the way down and the resistance is 10K or Vout 15 10 000 26 500 5 66V In reality we measured 3 different EV 5 pedals and found the pot to be closer to 9200 ohms which limits the output to almost exactly 5 0V Close enough The offs
12. IMPORTANT NOTE The expected DC output of the MOTM 850 is based on setting the jumper JP3 to generate a 0 to 5V voltage into R24 as the pedal is pressed from up to down This may not be the case if the pedal pot is not 10K 50K or 100K or if your CV out pedal has a different range say 0 to 6V out If you set JP3 incorrectly the voltage out of the module may be much higher or lower than expected So assuming everything is set correctly here are some expected outputs based on various RANGE and OFFSET knob settings RANGE SETTING OFFSET SETTING OUTPUT OF MOTM 850 x V GE 0 TO 5V Doesn t matter OFFSET reading 2 5V to 7 5V Several things can be seen from this table First if the RANGE is set negative the output voltage of the module decreases as you press the pedal down Second you can use the OFFSET control to tune the CV out of the module while the RANGE control sets the overall swing of the voltage You can also think of OFFSET as what voltage the pedal outputs when all the way up ie where the voltage starts from You can also control if the output voltage increases or decreases as the pedal is pressed Pretty neat huh A hidden usage is not plugging in a pedal at all and using the OFFSET control as a DC source or to add DC offset to whatever in fed to the MIX IN SYNTHESIS TECHNOLOGY PAGE 16 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM USING MIX IN MIX IN is an optional
13. N synthesis MOTM 850 Pedal Interface Assembly Instructions amp Owner s Manual Synthesis Technology 6625 Quail Ridge Dr Fort Worth TX 76180 817 281 7776 www synthtech com Oct 25 2001 MOTM 850 PARTS LIST Please carefully check that all parts are in your kit If you have a suspected shortage please call or email If you get free extra stuff keep it for next time Capacitor bag containing the following 10 parts 468 10mfd 50V Electrolytic C3 C6 C7 C8 668 0 1mfd marked 104 ceramic axial C1 C2 C4 C5 C9 C10 Resistor bag containing the following 24 parts 5ea 10K brown black orange R1 R6 R8 R14 R19 468 47K5 1 yellow violet green red R12 R13 R20 R23 3ea 820 ohm gray red brown R3 R7 R22 268 332K 1 orange orange red orange R2 R24 2ea 68K blue gray orange R4 R5 2ea 180K brown gray yellow R9 R10 2ea 715K 1 violet brown green orange R15 R21 lea 620K blue red yellow R11 lea 100K 1 brown black black orange R16 lea 82K5 1 gray red green red R17 lea 16K5 1 brown blue green red R18 IC bag containing the following 5 parts lea 2N3904 NPN transistor Q1 lea LM311N comparator U1 lea LM78L12 12V TO 92 regulator U2 lea LM79L12 12V TO 92 regulator U3 lea LT1013 precision dual op amp U4 Misc 1 bag containing the following 6 parts 2ea Axial ferrite beads plain gray things L1 L2 lea MTA 156 power connector JP1 2e
14. PC BOARD TO BRACKET PANEL In the HARDWARE bag locate 4 6 32 x 1 2 screws 6 6 KEPS nuts and 4 spacers Locate the mounting bracket The pc board attaches to the bracket with the 4 screws threading from the top of the board through the spacers through the bracket and then out the bottom of the bracket The 6 KEPS nut attaches on the bottom of the bracket Note the bracket has 2 long mounting flanges with a hole SYNTHESIS TECHNOLOGY PAGE 9 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM g in each These attach to the 2 threaded studs sticking out of the rear of the panel The 4 pots each stick in its panel hole when the bracket is screwed down on the 2 threaded posts Attach the pc board to the bracket The flanges will point upwards when the pc board is sitting on the bracket Note that the bracket holes for the pc board are actually oblong This is to allow adjustment for the pc board to firmly press up against the back of the panel As a start set the 4 screws ALL THE WAY TO THE LEFT of the oblong holes Loosely tighten the 4 KEPS nuts on the bottom THIS IS A VERY IMPORTANT STEP SO PAY ATTENTION AND READ ALL OF IT BEFORE PROCEEDING Note that each of the 4 pots on the pc board have 2 hex nuts and a flat washer Remove the first hex nut and the washer Set aside What you will do now 18 adjust the remaining hex nuts so that when the bracket 18 all the way down on the panels threaded studs all the pot hex nuts touch
15. a 3 pin header with shunt JP2 JP3 lea red LED panel mount D1 J Knobs 4ea ALCO PKES90B1 4 Jacks lea Switchcraft 112B stereo Jack J1 368 Switchcraft 112A mono jack J2 J3 J4 SYNTHESIS TECHNOLOGY PAGE 2 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM Pots 468 containing the following 468 100K cermet Spectrol 149 71104 VR1 VR4 Front panel d Mounting bracket Wire bag containing the following 6 wires 368 RG 174 coax 4 inches lea 2 wire set 2288 3 inches red black lea 3 wire set 22ga 2 inches orange white gray lea Power Cable 20 Hardware bag containing 4ea 8 32 x 3 8 black screws for mounting module to rack 4ea 6 32 x 1 2 zinc screws for attaching pc board to bracket 4ea 1 4 inch aluminum spacers 6ea 6 KEPS nuts 2 for attaching bracket to front panel 4 for pc board 2ea small heat shrink tubing 468 small tie wraps Organic Solder No clean Solder PC Board MOTM 850 UU L SYNTHESIS TECHNOLOGY PAGE 3 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM GENERALINFORMATION Thank you for purchasing the MOTM 850 Pedal Interface If you have any issues concerning the building or use of the kit please contact us at 817 281 7776 or by email syntht yahoo com This kit should take the average builder between 2 to 3 hours The kit contains many different resistors and special parts However please remember this is NOT a speed contest lt is an accuracy contest Th
16. aight into R24 Since the output impedance of the CV pedal is low R24 has no effect The CV can be mixed scaled and offset with ease USING THE MOTM 850 This first thing is to determine which type of pedal you have If you have a passive volume pedal like the Ernie Ball these will NOT work If the pedal plug is a 3 conductor then it is some sort of resistive pedal With a DVM measure the resistance between Tip and Ring as you move the pedal up and down Note the maximum resistance usually when the pedal is depressed all the way down Use the following table to set the jumpers PEDAL RESISTANCE MAX JP3 SETTING 5K 15K OHMS o R 15K 75K OHMS 75K 150K OHMS OPEN PARKED It doesn t matter if the Tip is the wiper of the pedal pot or not the MOTM 850 circuitry will compensate SYNTHESIS TECHNOLOGY PAGE 15 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM If you have a CV out pedal 2 conductor plug has batteries remove or park the shunt in JP3 The following is a description of each control RANGE This control sets the maximum output voltage of the module assuming OFFSET is set to zero The output voltage is 5V to 5V OFFSET This is a DC voltage which is added to the pedal output The range is 2 5V to 2 5V The combination of RANGE and OFFSET allows you to set the total DC voltage range as the pedal is pressed from full up to full down See the following table for some examples in using RANGE and OFFSET
17. and sometimes the color bands are difficult to read When in doubt use a DVM to measure the value NO guessing The rule of soldering don t use too much you can always add more Cut the leads flush with the top of the solder joint with your diagonal cutters Locate the 10K resistors 5pcs Solder the resistors into R1 by VR8 R6 left of U3 R8 above VR3 R14 above R8 and R19 right of C10 Locate the 47K5 1 resistors 4 and solder into R12 and R18 left of U4 R20 above R19 and R23 top edge of pcb by C5 Locate the 820 ohm resistors 3 and solder into R3 left of U1 R7 between VR2 and VR3 and R22 by J2 Locate the 332K 1 resistors 2 and solder R2 above C1 and R24 by VR1 Locate the 68K resistors 2 and solder into R4 and R5 above VR3 Locate the 180K resistors 2 and solder into R9 and R10 beside VR2 Locate the 715K 1 resistors 2 and solder into R15 left of U4 and R21 right of U4 Locate the 620K resistor and solder into R11 between R20 R21 Locate the 100K 1 resistor and solder into R16 left of VR3 Locate the 82K5 1 resistor and solder into R17 above R16 Locate the 16K5 1 resistor and solder into R18 above R17 PART 2 BOARD WASH 1 Verify all the resistors are in the correct position Verify all the resistors are flat on the board Correct if needed Check solder joints Wash the board In warm water gently scrubbing both sides DO NOT USE ANY SOAP J
18. c flux solder All soldering past this point is using the No Clean solder You do not have to wash the board anymore PART 6 FINISHING THE PCB You will now solder in the remaining parts on the pcb in preparation for wiring to the front panel USE THE NO CLEAN SOLDER BE CAREFUL g Locate the Spectrol pots They mount into VR1 VR4 Be sure they are flat and sticking out perpendicular to the pc board Locate the 8 pieces of RG 174 black coax cable Again note that one end has longer wires stripped than the other The short ends will go in the pc board in locations J2 J3 and J4 Look at the pc board Notice that in the coax positions there is a large hole pad lower pad and a smaller pad top hole The braided wire is soldered into the larger hole The smaller inner conductor goes in the top hole BE SURE THE SHORTER BRAIDED END GOES INTO THE PC BOARD SYNTHESIS TECHNOLOGY PAGE 8 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM Solder each coax cable into the holes Attach a tie wrap to secure the coax cable flush to the board The tie wrap goes down into the left hole and up through the right hole Secure and trim off any excess Find the red black twisted wire It goes into D1 Solder the Red wire into pad 1 and the Black wire into pad 2 Find the orange white gray wire It solders into J1 The White wire goes in pad 1 the Orange wire into pad 2 and the Gray into pad 3 Carefully cut the ty wrap off the bundle
19. ere is no rule that you have to complete the entire kit in one day as long as you wash the flux off Successful kit building relies on having the proper tools Here is a list of what you will need to build your MOTM 850 Soldering iron 50W max power Needle nose or chain nose pliers Diagonal cutters Allen key set for securing the knobs 1 16 or 1 6mm Magnifying glass to read the capacitor codes and to inspect solder joints Lead bending tool optional but makes the job go much faster DVM Digital Volt Meter or oscilloscope to check the output 1 Philips screwdriver Fingernail brush for washing off the organic flux Old towel for blotting dry pc board Heat shrink gun is highly reeommended For more information of tools used and suggestions see the MOTM FAQ and Tutorial pages at http www synthtech com HOW TO FOLLOW THE DIRECTIONS Please read the entire instruction before proceeding There may be valuable information at the end of the instruction Each instruction has a check box LJ next to it After you complete the instruction check the box This way you can keep track of where you are in the process VERIFY THE PARTS LIST Verify that all of the parts are in the kit as shown on the parts list SYNTHESIS TECHNOLOGY PAGE 4 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM A WORD ON SOLDERING There are 2 very different types of solder used in the kit Most of the soldering uses Organic Flux solder This
20. et trimmer simply adds resistance to the ground side of the pedal pot If the trim 18 set to 10 or 50K the output will lift off ground and be from 9 6V to about 11 4V This is out of the 850s operating range So be sure to keep that trim set below 3 or soll INTERFACING TO THE YAMAHA FC PEDAL The Yamaha pedals do not have the additional trimmer It s just a single 50K pot BUT as we said earlier they switched the tip and ring connections around See Figure 2 YAMAHA FC PEDAL Td DWN PEDAL 50K Since the pedal pot 1s 50K they must use better pots because the 4 we measured were all within 2 of 50K we need about 100K of series resistance to get out 0 to 5V output The voltage output in the Yamaha configuration is complicated because we are driving the wiper of the pot The series combination of R17 and R18 is 99K So the maximum voltage out is Vmax 15 50 99 50 5 03V If you really want to go through the math of the actual voltage out versus pedal position please go ahead Now lets talk about R24 The clever reader will plot these out and see that the voltage out is non linear with pedal position This is because the voltage divider is based on the x 1 x curve So since we are perfectionists R24 16 added The value is quite large compared to the pedal resistances AND to the RANGE pot VR1 This adds it s own series resistance to the
21. first and discard There is another ty wrap used to secure the 3 wires ina bundle to the pcb YOU ARE NOW FINISHED WITH THE PC BOARD WORK BREAK TIME PART 7 FRONT PANEL PREPARATION You will now attach components to the front panel It is HIGHLY recommended that you use a set of hollow shaft nut drivers NOT PLIERS to tighten the nuts This prevents scratching NOTE all references to part orientation is from the REAR of the panel Locate the 4 Switchcraft jacks Notice that from the rear there is a beveled corner This corner is ALWAYS CONNECTED TO GROUND USUALLY WITH A BRAIDED CONDUCTOR Each jack has a flat washer a lockwasher and a hex nut Remove the nuts and washers from each jack Place aside Keep the lockwasher on the jacks Also one of the jacks has 3 lugs but in a different location that the others This jack is for the pedal to plug into and it MUST go into the PEDAL hole Insert the 4 jacks lockwashers with the beveled corner in the upper right corner into the 4 holes Be sure the jack in the PEDAL hole has the lug in the bottom position when viewed from the rear Place the flat washer on the jack then the hex nut Hold the jack with one hand on the backside keeping it square Tighten the hex nut with a nut driver NOTE when tight not much of the exposed threads of the jack are exposed You are now ready to attach the pc board to the bracket and then wire up to the panel PART 8 ATTACH
22. input that is added at unity gain to the pedal output The panel control MIX is a simple attenuator so there is no gain associated with this signal An example is to insert the CV out of a keyboard and the MOTM 850 can add pedal portamento effects or even theremin type glides to VCOs Remember this is just a DC offset to the MIX signal it s not a volume control function V CA USING THE GATE OUTPUT The important thing to understand about the GATE control is how the LM311 actually is connected The LM311 compares 2 voltages the panel pot GATE and the instantaneous DC output of the module If the voltage of the CV out jack EXCEEDS the setting of the GATE pot the GATE is active and the LED lights up What can be confusing is the meaning of exceeds Since we are dealing in both positive and negative voltage polarities you have to remember that the more negative a voltage 18 the smaller with respect to positive voltages it is Again we are talking in relative algebraic terms here not real world So suffice to say that in terms of the GATE threshold any positive voltage exceeds a negative voltage In other words 1V exceeds 7V and 2V exceeds 3V Think of a number scale like you had in third grade with 0 in the middle Numbers to the right of 0 positive are bigger than numbers to the left of zero negative In general a number to the right exceeds any numbers
23. ono and only needs ground and CV OUT The pedals we will use as examples for resistive types are the Roland EV 5 and the Yamaha FC7 FC9 series They are probably others but these two cover the kinds you are likely to use In general the resistive pedals are nothing more than a simple potentiometer pot in a fancy case The pot is used as a voltage divider to output 0 to 5V This in turn feeds the range offset circuits and the Gate extractor This all sounds simple enough but to make matters errrrr interesting Yamaha and Roland on purpose wired their pedals up differently and use different pot values But being the clever people that we are theses differences are compensated for in the design of the MOTM 850 Before we go into how the 3 types of pedals are dealt with let s look downstream at the other circuitry Dual precision op amp U4 MXL1018 type is used to condition the output voltage from the pedal to a wide range of possible outputs U4A is a reversible attenuator with unity gain The RANGE pot VR1 splits the pedal voltage into an inverter U4A to straight through to inverting summer U4B We can also add in an external signal MIX IN through VR4 and R15 Note that in the U4A stage the MIX IN signal is attenuated by the ratio of R12 R15 but the gain is made up by the ratio in U4B of R21 R23 to have unity gain end to end U4B can also add in DC offset via pot VR2 Resistors R9 and R
24. s are pointing up towards the top edge of the pc board if you call where the pots are the bottom edge The IC will have a notch or indentation in the top by Pin 1 Locate the LM311 comparator Solder into U1 Locate the 2N3904 transistor DO NOT GET IT CONFUSED WITH THE 2 VOLTAGE REGULATORS Solder into Q1 SYNTHESIS TECHNOLOGY PAGE 7 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM Locate the LM78L12 voltage regulator DO NOT GET IT CONFUSED WITH THE 79L12 REGULATOR Solder it into U2 Locate the LM79L12 voltage regulator Solder it into U3 Save the LED for later Apply a small bit of solder to the via holes These are the small pads that allow traces to change sides of the pc board DO NOT SOLDER PADS FOR THE REMAINING COMPONENTS As an example if you look at the mounting hole by J1 you will see 3 via holes around it Solder the 2 3 pin header strips into JP2 and JP3 Remove the blue shunts and DON T LOSE THEM PART 5 FINAL BOARD WASH amp INSPECTION g J J Verify all the parts are in the correct locations Make sure all of the ICs are pointing the same direction Make sure the 3 TO 92 parts transistor voltage regulators are facing the same direction Inspect the solder joints Any solder shorts Too much solder Missing joints Wash the board under warm water Scrub gently Dry THIS IS A GOOD STOPPING PLACE TO REST OR PUT THE KIT AWAY UNTIL LATER You are now finished with the Organi
25. t the pc board with the panel to the right and the power connector to the left All of the ICs are pointing the same way up towards the edge away from the panel The braided wire on the coax goes to the beveled side of the Jacks r The parts are in the right places none of the 4 orange electrolytics in backwards CJ No solder shorts or missing joints If the LED doesn t light check the module output with a DVM Check JP3 for the proper setting SYNTHESIS TECHNOLOGY PAGE 18 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM Pedal resistances DC output range GATE voltage MIX input range CONTROLS RANGE OFFSET GATE MIX GENERAL Power Supply Size Depth behind panel SYNTHESIS TECHNOLOGY MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM SPECIFICATIONS MOTM 850 Pedal Interface 10K 50K 100K nominal jumper selectable 7 5V to 7 5V nominal 12V max OV min TV to 7V nominal Sets the over pedal response range Sets the DC offset of the pedal Sets the GATE threshold Attenuates the signal applied at MIX IN 15VDC 10 ma nominal 15VDC 15 ma nominal 1U x 5U 1 72 x 8 72 44mm x 221 5mm 2 375 inches 60 3mm PAGE 19 3SSus L00 lt 0141 GuueAON 3edC HOVHAALNI IWdHd a ASGUNN 3uUu umn ocq z rs oss WLOW WLOW 8T8 O8T9L GEKRWKERSISE
26. ust water SYNTHESIS TECHNOLOGY PAGE 6 MOTM 850 ASSEMBLY 10 25 01 WWW SYNTHTECH COM g g Shake the board a couple of times blot dry with an old towel the leads will frazzle a good towel Let dry at least 15 minutes Take a little break You are about 1 8rd of the way finished PART 3 CAPACITORS J J g Locate the CAPACITOR bag Locate the 0 1mfd axial ceramic caps 6 and solder into C1 C2 C4 C5 C9 and C10 Note that these are bent on 0 3 centers Locate the 10ufd electrolytics 4 Note that there is a stripe on the NEGATIVE terminal The pc board has a on the POSITIVE terminal Carefully stick the capacitors into C3 C6 C7 and C8 with the stripe away from the pad on the board All the capacitors will face the SAME DIRECTION PART 4 MISC and IC STUFF Almost done with the parts on the pc board This will finish up the soldering with the organic flux Locate the MISC 1 bag and the IC bag Locate the ferrite beads 2 They are axial parts gray colored with no markings These are non polar and are soldered into L1 and L2 by JP1 Locate the MTA 156 power connector Solder into JP1 Note that the connector has a locking tab on one side This side is the inside facing relative to the pc board Note the silkscreen symbol for JP1 has a line on one side indicating this is the side where the locking tab goes Locate the MXL1013 op amp Solder into U4 Note that all IC
Download Pdf Manuals
Related Search