MOTM-820 User Manual
Contents
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3. and solder into R12 turned sideways by U2 g Locate the 1K8 resistor and solder into R31 by J4 g Locate the 100 ohm resistor and solder into R4 last one left PART 2 BOARD WASH 1 3 Verify all the resistors are in the correct position SYNTHESIS TECHNOLOGY PAGE 6 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM 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 Just water 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 3rd of the way finished PART 3 CAPACITORS o 0 Locate the CAPACITOR bag Locate the 0 1mfd yellow box cap and solder into C7 lower left of U3 Locate the 0 001mfd yellow box caps 2 and solder into C1 above J2 and C12 by J8 Locate the 22pf ceramic axial cap and solder into C4 left of U1 Locate the 0 1mfd axial ceramic caps 6 and solder into C2 C3 C5 C6 C8 and C9 Locate the 10ufd electrolytics 2 Note that there is a stripe on the NEGATIVE terminal The pc board has a on the POSITIVE terminal Carefully stick the capacitors into C10 and C11 with the stripe away from the pad on the board 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 Save the trim
4. in its panel hole when the bracket is screwed down on the 2 threaded posts Attach the board to the bracket The flanges will point upwards when the 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 board have 2 hex nuts and a flat washer Remove the first hex nut and the washer Set aside What you will do now is adjust the remaining hex nuts so that when the bracket is all the way down on the panel s threaded studs all the pot hex nuts touch the rear of the panel Screw by hand each hex nut on the pots so that it is all the way on touching the face of the pot Now pick up the pc board bracket assembly and carefully slide it 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 n
5. please contact us at 888 818 MOTM 6686 or by email synth1 airmail net This kit should take the average builder between 3 to 4 hours The kit contains many different resistors and special parts However please remember this is NOT a speed contest it is an accuracy contest There 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 820 Soldering iron 5 0W 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 board Heat shrink gun is highly recommended 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 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 3 Ver
6. pot for later o 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 SYNTHESIS TECHNOLOGY PAGE 7 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM 3 Locate the MXL1013 op amps 2 Solder into U1 and U2 Note that all ICs are pointing down towards the bottom edge of the board The IC will have a notch or indentation in the top by Pin 1 g Locate the 1N4148 diode Notice it has a black band near one end This is the cathode and there is a matching band on the silkscreen for D1 Solder the diode with the banded end pointing to the left 3 Locate the TL084 amp Solder into U3 Locate the DG213DJ Solder into U4 3 Locate the BC550C transistors 8 Match the flat side of the part to the flat side shown on the silkscreen Place the transistor in the holes but do NOT press the transistor all the way to the pe board Leave about 0 1 inch of the leads exposed between the pc board and the underside of the transistor Solder into Q1 Q3 and Q4 g Locate the BC560C transistors 2 Sol
7. 4 00 WWW SYNTHTECH COM Solder the coax in J6 to the jack Solder the red black wire in J2 to the UP jack Solder the long coax in J5 to the IN jack Solder the orange white wire in J1 to the BYPASS jack White to left lug Orange to beveled 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 kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk CONGRATULATIONS YOU HAVE FINISHED BUILDING THE MOTM 820 All that s left to do is test it But before we do please read the following Theory of Operation THEORY OF OPERATION The MOTM 820 if we do say so ourselves is quite a clever circuit It is a tricked up dual exponential converter which forms a precision 2 quadrant multiplier with zero offset voltage Since the main use of the 820 is adding portamento effects to control voltages feeding a MOTM 300 VCO DC precision is paramount Errors of 500uv are audible so the 820 uses several precision components to achieve absolute lowest DC offset and drift On Page 2 of the schem
8. 5 lea 1N4148 diodes D1 2ea MXL1013 dual op amp 01 U2 TL084 quad op amp U3 lea DG213DJ CMOS quad switch U4 3 Misc 1 bag containing the following 6 parts 2ea Axial ferrite beads plain gray things L1 L2 lea MTA 156 power connector JP1 lea SPDT ON ON toggle switch SW1 lea 5K Bourns trimpot 25 turn TP1 lea red LED panel mount D2 SYNTHESIS TECHNOLOGY PAGE 2 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM 1s Knobs 4ea ALCO PKES90B1 4 Jacks Switchcraft 112A g Pots 4ea containing the following 4ea 100K cermet Spectrol 149 VR1 g Front panel Mounting bracket 3 Wire bag containing the following 11 wires RG 174 coax 4 inches lea RG 174 coax 7 inches lea 2 wire set 22ga 6 inches orange white 2 wire set 22ga 3 inches red black lea Power Cable 20 3 Hardware bag containing 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 6 KEPS nuts 2 for attaching bracket to front panel 4 for board 2ea small heat shrink tubing 5ea small tie wraps Organic Solder No clean Solder PC Board MOTM 820 OOO SYNTHESIS TECHNOLOGY PAGE 3 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM GENERAL INFORMATION Thank you for purchasing the MOTM 820 Voltage Controlled Lag Processor If you have any issues concerning the building or use of the kit
9. P1 so that there is less than 1mv of difference between BYPASS and un bypassed This point is when you can t hear any pitch change in the monitored audio or the DVM changes less than Another way to do this if you have 2 VCOs is to feed VCO 1 with the straight CV and VCO 2 with the lagged CV Set the VCOs for zero beating and adjust the trimmer by ear for zero beats in and out of bypass IMPORTANT NOTE In order for best bypass operation ie no offset between the lagged voltage and the original the source impedance of the signal must be below 100 ohms Commercial MIDI to CV converters and CV outs of older analog keyboards SH 101 etc meet this criteria However if you are using a voltage out from a MOTM module say a MOTM 800 ADSR that has a 1000 ohm impedance there will be approximately a 8mv differential that cannot be trimmed out Again in the normal use of the MOTM 820 to add portamento to CVs originating from a MIDI to CV converter or from the CV Out of an analog synth will have adjustable offset to zero TROUBLESHOOTING If your MOTM 820 does not work please verify ALL of the following before contacting us The following reference directions assume that you are looking at the pc board with the panel to the right and the power connector to the left g All of the ICs are pointing the same way and all notches are down Diode D1 is pointing band side to the left All transistors flat sides are f
10. acing the panel g The braided wire on the coax goes to the beveled side of the jacks 3 The parts are in the right places and the panel pots switch are wired correctly 3 No solder shorts or missing joints If the LED doesn t light you reversed the leads USING THE MOTM 820 The main use of the 820 is to add portamento also called glide or slew to the control voltage driving a MOTM 300 VCO If you have older analog synths this is a common feature However traditional circuits have 2 limitations a the rise and fall times are the same b the shape is always exponential a simple RC charging circuit SYNTHESIS TECHNOLOGY PAGE 14 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM The MOTM 820 is unique it has independent rise fall times called UP and DOWN for no particular reason and a shape control Also the times can be set by control voltages over a wide range from less than 1015 to over 10 seconds Already a small portion of MOTM abusers are thinking what happens if I run audio through this thing The answer is this is a lowpass filter but the controls will only be useful over a narrow range say 0 to 2 Certainly the circuitry doesn t know if the input is DC or audio it happily slews it BASIC PATCH 1 Set all panel controls to 0 Set the BYPASS switch to OFF unit is in the signal path 2 Patch a pitch control voltage one that you would normally use to control a VCO to the IN jack 3 Patch
11. atic look at U1B C4 R11 and Q2 If this configuration looks familiar that s because it is an exponential converter Normally one end of R11 1 tied to some voltage that generates a reference current see the MOTM 420 schematic for example In the MOTM 300 VCO this is also where linear FM voltage is applied That s because the transistor has an intrinsic multiplication capability the output current is equal to the reference current multiplied by the exponential base emitter voltage The output current feeds an integrator formed by C7 and U3D So if we apply the voltage to be slewed as a reference current then changing the base emitter voltage would cause the integrator s rise fall time to vary If you have a MOTM 300 read over the Theory section in the manual about the exponential converter for more understanding Having only one exponential converter means we can only slew for positive going inputs So we use 2 exponential converters a NPN set Q3 Q4 and a PNP set Q2 Q5 These sets SYNTHESIS TECHNOLOGY PAGE 12 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM are cross coupled so that when the input voltages changes polarity the NPN PNP pairs switch and the current into C7 is either sucked slewing down or blown slewing up C4 keeps high speed oscillation out of the circuit The UP and DOWN slew rates are set by applying small voltages to the bases of Q3 Up and Q5 Down Since we have inde
12. der into Q2 and Q5 3 Apply a small bit of solder to the via holes These are the small pads that allow traces to change sides of the board DO NOT SOLDER PADS FOR THE REMAINING COMPONENTS As an example if you look at J1 you will see 4 via holes around it PART 5 FINAL BOARD WASH amp INSPECTION 3 Verify all the parts are in the correct locations Make sure all of the ICs are pointing the same direction Make sure all of the transistors are facing the same direction 3 Inspect the solder joints Any solder shorts Too much solder Missing joints g Wash the board under warm water Scrub gently Dry THIS IS A GOOD STOPPING PLACE TO REST OR PUT THE KIT AWAY UNTIL LATER Don t lose the trim pot it goes on with no clean solder in the next section You are now finished with the Organic 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 SYNTHESIS TECHNOLOGY PAGE 8 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM Locate the Bourns 5K blue trim pot Solder it into TP1 Be sure it is flat on the board Locate the Spectrol pots They mount into VR1 VR4 Be sure they are flat and sticking out perpendicular to the pc board Locate the 4 pieces of RG 174 black coax cable Again note
13. esistors 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 start by soldering in ALL of the resistors C Find the RESISTOR bag g Find the MOTM 820 blank pc board There is 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 3 We will stuff the resistors 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 is 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 sho
14. ify that all of the parts are in the kit as shown on the parts list SYNTHESIS TECHNOLOGY PAGE 4 MOTM 820 ASSEMBLY 12 4 00 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 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 R
15. ne limitation of this design is that the 3 control voltage inputs MUST be positive voltages Applying negative inputs may produce high frequency oscillation Since inputs are all positive then you can only INCREASE the slew rates Certainly reducing the control voltages say from 3V to 1V reduces the time constant But the MOTM 820 is NOT like other modules that can accept both positive and negative control voltages SYNTHESIS TECHNOLOGY PAGE 15 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM d Since we are driving exponential converters with our control voltages the slew times will roughly double every tick mark on the panel The MOTM 820 has a very wide operating range on the order of 20 000 1 Just be aware of this REMOTE BYPASSING If you want to use a footswitch to bypass the MOTM 820 then a be SURE the BYPASS switch on the front panel is set to OFF Otherwise it over rides the jack b Get any simple SPST switch and wire a patch cable across it It doesn t matter which terminal is ground and which is the center conductor Then patch it into the BYPASS jack When the remote switch is closed the jack shorts itself to ground causing the unit to go in BYPASS Industrial footswitches are easily adapted for this An example is Allied Electronics part 842 6091 This uses a SPDT switch which you would wire the cable across the NC normally closed side In this manner the MOTM 820 is in BYPASS until you step on the
16. pendent Up Down we can get the same Up Down times by applying the same voltage to both Q3 and Q5 This is what U8C does Since the voltage on the bases is small say 0 to 300mv passive dividers like R20 R21 are used to reduce the nominal 0 to 5V control inputs Looking at the UP portion R8 and VR1 form a 3 1 divider buffered by So the output goes 0 to 5V If an external input of 0 to 5V is plugged into J2 then VR1 acts like an input attenuator since R8 amp s resistance will be 200 times the typical output impedance of the source The control voltage is divided by 16 by R16 R17 R18 is just to bias the base slightly negative to ensure it s really off when switched out U2A and U2B are inverters drivers for the exponential converters U2A is a precision inverter whose gain is set over a tiny range by trimmer TP1 This nulls out offset voltages caused by the circuitry from the bypass switch IC U4 Due to the nature of the internal construction of U4 the offset is a linear function of applied DC voltage That is why the trim pot is set as a gain as opposed to the more traditional configuration of DC offset voltage into a summing node The shape of the slew for both directions is set by VR4 This is another divider that adds in positive feedback through R30 to get a linear shape The BYPASS function is half of quad switch U4 It is wired as a SPDT switch controlled by the voltage on pins 8 and 9 Normally R3
17. pulls up to 15V which closes the connection between pins 6 and 7 while opening the connection between 10 and 11 This enables the lag function Transistor Q1 is on which shorts out LED D2 so it is off If the panel switch SW1 is in BYPASS or the tip sleeve of J1 is shorted causes pins 8 and 9 of U4 to go to 0 volts reversing the 2 analog switches and bypassing the lag circuitry Diode D1 prevents the voltage from going below ground in case you decide to plug a bipolar voltage into BYPASS The processed input voltage is fed to line driver U1A The op amp is configured as a unity gain driver for large capacitive loads This output stage can drive 3 separate patch cables each 8 feet long Note that there are 3 ganged outputs so driving 3 VCOs is a breeze SETTING THE OFFSET TRIMMER There is one adjustment setting TP1 to have exactly zero DC voltage offset when switching in out of BYPASS You can do this with a good DVM one that can read to at least 1mv or by ear really the preferred way a apply a steady DC voltage to the IN jack We use a MIDI to CV converter on middle C b set UP DOWN and UP DN to 0 c set LIN LOG to 5 SYNTHESIS TECHNOLOGY PAGE 13 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM d monitor the OUT jack any one with either a good DVM or by plugging into a VCO oscillating VCF and listening turn 1 it uses a really tiny screwdriver while flipping the BYPASS switch You should be able to adjust T
18. r Anode lead towards the top panel edge looking from the rear this is towards the left Press the LED snugly to the panel Now cut off half of the LED s leads they are too long 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 Place the 2 pieces of heat shrink tubing down over the Red 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 8 jacks Each jack has 3 lugs from the rear we will refer to them as LEFT TOP and BEVELED The TOP lug is for the switched contact this is a NC normally closed contact that is opened when a plug is inserted Solder the coax in J8 to the OUTS jack The braid goes to the BEVELED lug The inner conductor goes to the LEFT lug This is true of ALL coax wires Solder red black wire in J4 to the UP DN jack The Black wire goes on the beveled lug The Red wire goes on the LEFT lug Solder the coax in J7 to the OUT2 jack Solder the red black wire in J3 to the DOWN jack Black wire to the beveled lug red wire to the left lug SYNTHESIS TECHNOLOGY PAGE 11 MOTM 820 ASSEMBLY 12
19. rear there is a beveled corner This corner is ALWAYS CONNECTED TO GROUND USUALLY WITH A BRAIDED CONDUCTOR Each jack has flat washer lockwasher and a hex nut Remove the nuts and washers from each jack Place aside Keep the lockwasher on the jacks Insert the 8 jacks lockwashers with the beveled corner in the upper right corner into the 8 holes 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 Remember that resistor lead scrap you have been saving It solders on the IN jack SYNTHESIS TECHNOLOGY PAGE 9 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM Solder the scrap in between the TOP and the BEVELED lugs You are now ready to attach the pc board to the bracket and then wire up to the panel PART 8 ATTACH 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 in each These attach to the 2 threaded studs sticking out of the rear of the panel The 4 pots each stick
20. switch Then you are slewing until you take your foot off the pedal Other types of the footswitches are like stompboxes that use push ON push OFF switches EFFECT OF SHAPE IF you are used to hearing exponential glide on your old analog keyboard be sure you set the LIN LOG shape pot to 8 or above But the MOTM 820 can do variable shapes including linear straight line which sounds completely different Experiment with using different base LFO waveforms sine tri etc running fairly slow say lt 4Hz and changing shape as well as slew times You can create 100 s of strange LFO waveshapes in this manner SYNTHESIS TECHNOLOGY PAGE 16 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM SPECIFICATIONS MOTM 820 VC Lag Processor Control Voltage input levels OV to 7V Slew times UP DOWN lt 1ms to over 15 seconds Output impedance lt 1 ohm IN Level 6V pk pk CONTROLS UP Sets the upward slew time DOWN Sets the downward slew time UP DN Sets both upward and downward slew times LIN LOG Sets the shape of the transitions BYPASS jack Causes the unit to bypass if shorted GENERAL Power Supply Size Depth behind panel SYNTHESIS TECHNOLOGY MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM 15VDC 20 ma nominal 15VDC 25 ma nominal 2U x 5U 347 x 8 12 88 1mm 221 5mm 4 375 inches 111mm PAGE 17 T HOS OZ8W a ATA zequnn
21. synthesis technology MOTM 820 Voltage Controlled Lag Processor Assembly Instructions amp Owner s Manual Synthesis Technology 6625 Quail Ridge Dr Fort Worth TX 76180 817 498 3782 www synthtech com Dec 4 2000 MOTM 820 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 3 Capacitor bag containing the following 12 parts 2ea 10mfd 50V Electrolytic C10 C11 lea 22pf marked 220 ceramic axial C4 lea 0 1mfd marked 100N or 104 yellow box C7 2ea 1000pf yellow box marked 1N or 102 C1 C12 0 1mfd marked 104 ceramic axial C2 C5 C6 C8 C9 3 Resistor bag containing the following 32 parts 6ea 10K brown black orange R13 R14 R15 R27 R28 4ea 15K brown green orange R17 R19 R20 R23 4ea 51K green brown orange R2 R6 R26 R32 3ea 2K7 red violet red R5 R29 R30 3ea 200K red black yellow R7 R8 R9 2ea 1K brown black red R16 R21 2ea 120K brown red yellow R18 R22 2ea 100K 0 1 RN55E marked 1003B R24 R25 lea 470 ohm yellow violet brown R1 lea 100 ohm brown black brown R4 lea 7K5 violet green red R10 lea 475K 1 yellow violet green orange R11 lea 1 0M 1 brown black black yellow R12 lea 1K8 5 brown gray red R31 3 IC bag containing the following 10 parts 3ea BC550C NPN transistor Q1 93 Q4 2ea BC560C PNP transistor Q2 Q
22. that one end has longer wires stripped than the other The short ends will go in the board in locations J5 48 Look at the 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 The 1 LONG coax cable solders into J5 The 3 SHORT coax cables go into the other locations 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 5 red black twisted wires They go into D2 SW1 J2 J3 and J4 Solder the Red wire into pad 1 and the Black wire into pad 2 Note that for D2 and SW1 the red amp black wires are inverted with respect to the others Find the orange white twisted wires It solders into J1 The White wire goes in pad 1 and the Orange wire into pad 2 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 8 Switchcraft jacks Notice that from the
23. the OUT1 jack to the VCO or self oscillating VCF 1V OCT jack 4 Play notes and slowly turn the UP knob As the notes play you should hear the slewing only if the current pitch is greater than the last one Flip the BYPASS switch to verify that it works slewing goes away 5 Now experiment with all the knobs They are self explanatory Things to remember if you get unexpected results a If the input is changing faster than the UP and DOWN times then you will get distortion and attenuation For example if you are slewing the PULSE output of a MOTM 320 getting triangles and other waveforms you can set the panel controls so the output will be somewhere between 5V and 5V at a DC value In other words you can t have UP be 500ms and DOWN be 300ms and send in a wave that changes directions every 50ms Well you can but the output will be strange Of course for some of you this 15 exactly what you want Just understand why the module behaves the way it does Remember it is in effect a fancy lowpass filter b Traditional Symmetric portamento is set by using the UP DN knob This applies the same voltage to the UP and DOWN control paths Setting the LIN LOG pot to 10 duplicates standard portamento An important point the UP DN control adds voltage to the settings of UP and DOWN In other words if UP is on 2 and DOWN is on 3 setting UP DN on 4 is the SAME as UP on 6 and DOWN on 7 O
24. uld SYNTHESIS TECHNOLOGY PAGE 5 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM flow in the hole such that on the top component side a small amount is on the top pad as well 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 NOTE later in the assembly you will need a scrap of resistor lead Be sure to save a piece Locate the 10K resistors 6pcs Solder the resistors into R13 and R15 left of VR2 R14 eft of U3 R27 bottom right corner by D1 and R28 above U2 g Locate the 15K resistors 4 and solder into R17 above R23 R19 left of VR2 R20 above VR3 and R23 left of U3 g Locate the 51K resistors 4 and solder into R2 below Q3 R6 by L2 R26 left of VR3 and R32 below 93 g Locate the 2K7 resistors 3 and solder R5 top edge R29 beside J4 and R30 by VR4 g Locate the 200K resistors 3 and solder into R7 by VR2 R8 by VR1 and R9 by VR3 3 Locate the 470 ohm resistor and solder into R1 right of U1 g Locate the 1K resistors 2 and solder into R16 below SW1 and R21 by C8 g Locate the 120K resistors 2 and solder into R18 by VR2 and R22 by C8 g Locate the 100K 0 1 resistors 2 and solder into R24 and R25 left of VR3 Locate the 7K5 resistor and solder into R10 left of U1 g Locate the 475K 1 resistor and solder into R11 above R10 g Locate the 1 0M 1 resistor
25. uts 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 pot s 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 SYNTHESIS TECHNOLOGY PAGE 10 MOTM 820 ASSEMBLY 12 4 00 WWW SYNTHTECH COM Remove the hex nuts VR1 amp For all of the pots first put on the flat washer then the hex nut Tighten with 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 SPDT toggle switch Insert the switch into the panel hole labeled BYPASS Tighten the outside hex nut but DO NOT OVERTIGHTEN Be sure the switch is oriented so the lever operates up and down and not side to side The lockwasher goes on the inside of the panel Now you will solder to the BYPASS mode switch The SW1 Black wire goes to the CENTER lug The Red wires goes to the BOTTOM lug The TOP lug is not used 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 D2 The other lead is the Cathode and is soldered to the Black wire Insert the LED through the panel with the longe
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