MOTM-390 User Manual
Contents
1. 6TA ASt LTSSAN Wen NTO M6t AST MOTE z ALZA 9A MOOT n 1 _ T TEN 6AE T va MOOT 209850 tr MOSS THA 20 839 TA x oot EAA A o AST ED 62 MOOT ota E MEE SOISLWT ETA AS vn s CIC 50 BLK BLK JEU QNOD SL 9 vR2 E H ogni n 18 m mur J3 94 8 45 J2 78 URS J 005 25 lt 9 Or z Ou 2 o is Z5 ns Q I O T H c2. N synthesis technology MOTM 390 uLFO Assembly Instructions amp Owner s Manual Synthesis Technology 6625 Quail Ridge Dr Fort Worth TX 76180 817 281 7776 www synthtech com August 13 2002 MOTM 390 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 1t for next time Capacitor bag containing the following 9 parts 2ea 10mf 50V Electrolytic 1 62 220nf film reddish brown marked 224 cap C7 100nf film reddish brown marked 104 cap C8 O0 1mfd marked 104 ceramic axial C3 C6 C9 Resistor bag containing the following 37 parts 5 1 4 6ea 1K brown black red R15 R23 R29 R32 R34 R35 bea 220K red red yellow R1 R5 R12 R21 R28 dea 100K brown black yellow R7 R10 R20 R27 R33 4ea 20K red black orange R3 R22 R31 R37 3ea 39K orange white orange R13 R14 2ea 2K7 red violet red R17 R24 2ea 56K green blue orange R18 R25 2ea 3300 orange orange brown R19 R26 2ea 10K brown black orange R30 R36 6K8 blue gray orange R2 3K9 orange white red RA 8K2 gray red red R6 4K7 yellow violet red R9 820 gray red black R11 62K blue red orange R16 IC bag containing the following 10 parts 2ea TLO74ACN quad op amp U1 U2 lea NE5517 dual OTA U3 lea 78LO5A
3. all the resistors are flat the board Correct if needed Check solder joints Wash the board 1n warm water gently scrubbing both sides 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 SYNTHESIS TECHNOLOGY PAGE 6 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM PART 3 Complete the Resistors 00 Locate 2K7 resistors 2 and solder into R17 Q4 and R24 by Q6 Locate the 56K resistors 2 and solder into R18 by Q3 and R25 by Q5 Locate the 330 ohm resistors 2 and solder into R19 D1 and R26 D2 Locate the 10K resistors 2 and solder into R30 by R31 and R36 by R37 Locate the 6K8 resistor and solder into R2 below Q1 Locate the 3K9 resistor and solder into R4 below R1 Locate the 8K2 resistor and solder into R6 above Q2 Locate the 4K7 resistor and solder into R9 by R8 Locate the 82 ohm resistor and solder into R11 above VR1 Locate the 62K resistor and solder into R16 right of U3 This completes the resistors Check your solder joints and wash the board again Let dry 15 minutes Take a little break PART 4 CAPACITORS Locate the CAPACITOR bag Locate the 0 1mf axial ceramic caps attached to the 2 pieces of removable tape and solder into C3 C4 C5 C6 and C9 Locate the 100nf stacked metal film cap marked 104 Solder into C8 Locate the 220nf
4. has 3 large holes on the flange where the 3 pots stick out The first step 1s to attach a hex nut without the washer and outer hex nut to each pot Tighten each nut by hand all the way until it touches the face of the pot Then loosen the nut one fourth of a turn Attach the pc board to the bracket You will have to angle the pc board slightly as you insert the 3 pots through the 3 large holes on the flange Place the 4 spacers over the 4 holes and thread the screws in from the TOP side 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 Slide the pcb ALL THE WAY TO THE RIGHT AS FAR AS IT WILL GO so that the 3 pot nuts are all pressing against the flange By hand put hex nuts on the outside threads of VR1 and VR3 to keep the pc board in place Now tighten the 4 KEPS nuts on the bracket The pcb and bracket should be secure with the pc board snugly against the flange SYNTHESIS TECHNOLOGY PAGE 10 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM Remove the hex nuts on VR1 amp VR3 Insert the pcb bracket assembly through the 3 pots holes on the rear of the front panel As you press the assembly in place place a washer and hex nut over each pot from the front Using a hollow shaft nut driver tighten each outer hex nut as far as it will go up against the washer PART 10 FINISH WIRING TO THE PANEL Please read the following instructions carefully I
5. in J3 to the TRI not TRI A out jack Solder the coax in J5 to the SINE jack Solder the coax J4 to the SQR A Jack Solder the coax in J1 to the TRI A jack Use the remaining ty wrap to gather up the coax wires in J1 J5 and bundle together Rotate all front panel pots fully counter clockwise Locate the KNOBS SYNTHESIS TECHNOLOGY PAGE 11 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM 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 kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk CONGRATULATIONS YOU HAVE FINISHED BUILDING THE MOTM 390 that s left to do is test it But before we do please read the following Theory of Operation THEORY OF OPERATION The MOTM 390 has 2 1ndependent sections a fixed frequency LFO and a voltage controlled LFO The fixed section 1s a simple triangle square oscillator based on integration capacitor C8 for an extremely detailed explanation see the MOTM 380 User Guide VR1 and R11 form a resistor divider that applies a current through R12 The smaller the current the lower the frequency Resistors R10 and R13 set the output to 5V pk pk The output of the comparator U2A is rail t
6. proper operation Please read ALL of an instruction before proceeding VERIFY THE PARTS LIST Verify that all of the parts in the kit as shown on the parts list SYNTHESIS TECHNOLOGY PAGE 4 MOTM 390 ASSEMBLY 8 13 02 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 15 embedded 1n 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 1n 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 1s 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 1s used for wiring the pots switches jacks etc This solder 1s harder to use on the pc board because even when melted it 1s 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 an
7. say 0 47uf on the slow side or use a value lower than 10nf for the fast mod Waveform distortion and or start up problems will occur SPECIFICATIONS MOTM 390 Voltage Controlled LFO Waveform output level Output impedance Frequency Range FM voltage range CONTROLS RATE A RATE FM GENERAL Power Supply Size Depth behind panel SYNTHESIS TECHNOLOGY MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM 10V pk pk nom 1000 ohms nom Fixed 0 08Hz to 33Hz 0 01Hz to 120Hz TV to 7 sets fixed LFO A output rate sets LFO B output rate attenuates the CV applied to FM jack 15VDC 10 ma 15VDC 10 ma 10 50 1 72 x 8 72 44mm x 221 5mm 3 5 inches 89mm PAGE 14 eT asnbny 2008 4 6 ONDIN NLON 8T8 888 OST9AL XL HINOM LAOA S299 ADOO IONHOH LL SISHHILLNAS deis SILIO Co TO 9ST WLW CI AAAS AST AST Lu LTSSHN den LAL e ZZA ANIS 5021 MOOT Sr AST LAZ MOOT D09cDad 90 a IAL LZA sca OEE MOG K A za e Dossa K
8. CZ 5V regulator U4 2ea BC550C NPN transistor Q3 Q5 4ea BC560C PNP transistor Q1 Q2 Q4 Q6 SYNTHESIS TECHNOLOGY 2 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM Misc 1 bag containing the following 5 parts 2ea Axial ferrite beads plain gray things L1 L2 156 power connector 2ea Red LED panel mount D1 D2 Knobs 3ea ALCO PKES90B1 4 Jacks Switchcraft 112A Pots 3ea containing the following 100K log cond plastic Spectrol 148 VR1 2ea 100K cermet Spectrol 149 VR2 VR3 Front panel Mounting bracket Wire bag containing the following 9 wires 4ea RG 174 coax 4 1nches RG 174 coax 7 1nches 2 wire set 22ga 3 2 inches red black Power Cable 20 Hardware bag containing 4ea 8 32 x 3 8 black screws for mounting module to rack 4ea 36 32 x 1 2 zinc screws for attaching pc board to bracket 4ea 1 4 inch aluminum spacers 4ea 6 KEPS nuts 4ea small heat shrink tubing small tie wraps Organic Solder No clean Solder PC Board MOTM 390 SYNTHESIS TECHNOLOGY PAGE MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM GENERAL INFORMATION Thank you for purchasing the MOTM 390 Micro Low Frequency Oscillator LFO If you have any issues concerning the building or use of the kit please contact us at 817 281 7776 or by email synth1 airmail net This kit should take the average builder between 3 to 4 hours The LFO kit cont
9. IRST Locate the 78LO5ACP voltage regulator It looks like a transistor Solder into U4 up there by L2 Match the flat side of the part to the flat 1ndication on the silkscreen Locate the 4ea BC560C transistors Solder into Q1 Q2 Q4 and Q6 Match the flat side of the transistors to the flat indication on the silkscreen Locate the 2ea BC550C transistors They solder into Q3 and Q5 Being careful NOT to solder the remaining component holes solder a small bit of solder to the via holes These are the small pads no components go in them that allow traces to change sides of the pc board DO NOT SOLDER PADS FOR THE REMAINING COMPONENTS The via holes need VERY SMALL AMOUNT solder An example of a via hole 1s to the lower left of JP1 above C3 PART 6 FINAL BOARD WASH amp INSPECTION g g Verify all the parts are in the correct locations Make sure all of the ICs are pointing the same direction as well as all of the transistors Inspect the solder joints Any solder shorts Too much solder Missing joints SYNTHESIS TECHNOLOGY PAGE 8 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM 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 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 7 FINISHING THE PCB You will now solder in th
10. ains many different resistors and special parts that require very accurate soldering skills However please remember this 1s NOT a speed contest 1t 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 390 Soldering iron 50W max power Needle nose or chain nose pliers Diagonal cutters Allen key set for securing the knobs 1 16 or 1 58mm 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 Small flat screwdriver for adjusting the trimmers Fingernail brush for washing off the organic flux Old towel for blotting dry pc board xo H 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 VERY IMPORTANT PLEASE READ It is critical that you follow the steps exactly in order for
11. e LED leads Probably the easiest fix is to swap the wires in 01 02 OK so they won t match the silkscreen anymore The braided wire on the coax goes to the beveled side of the jacks The board has all the right parts in all the right places If you still can not get the module to perform correctly please contact us by phone at 888 818 MOTM or by email to synth1Qairmail net USE OF THE MOTM 390 LFO The MOTM 390 is used to add time varying modulation to VCOs VCFs VCAs and just about any module with a CV in jack All 5 outputs can be used at the same time The SQUARE output of the lower section is useful for triggering MOTM 800 EGs it likes square waves best Since the exponential converter 1s not temperature compensated and the transistors are not thermally matched the LFO speed will drift over temperature The drift 1s on the order of say 5 over a 30F change Chances are you will never see such a change in cabinet temperature The circuit is not intended to be a VCO substitute although some will try The voltage controlled section has a much wider frequency span than the fixed LFO SYNTHESIS TECHNOLOGY PAGE 13 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM You can change the maximum frequency simply by changing capacitors C7 and C8 The smaller the value the faster the frequency Of course this also changes the lowest frequency as well The capacitors need to be metallized film types or polystyrene Don t exceed
12. e remaining parts on the pcb in preparation for wiring to the front panel USE THE NO CLEAN SOLDER BE CAREFUL Locate the Spectrol pots 3 IMPORTANT in order for the pc board to properly align g with the front panel each pot must be absolutely flat on the pc board with the shafts pointing away from the pc board Solder the log pot into marked 148 9609 104 and the 2 linear pots into VR2 and V R3 Locate the 5 pieces of RG 174 black coax cable Again note that one end has longer wires stripped than the other Look at the pc board Notice that in the coax positions there 1s 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 longer piece of coax solders into J3 The shorter coax solder into J1 J4 J5 and J6 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 3 red black twisted pairs They go into D1 and D2 in the holes RED and BLK and J2 black into TOP 1 hole and the red wire into the BOTTOM 2 hole YOU ARE NOW FINISHED WITH THE PC BOARD WORK BREAK TIME SYNTHESIS TECHNOLOGY PAGE 9 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM PART 8 FRONT PANEL PREPARATION You will now a
13. ing out From the bottom of the board solder using the organic flux SYNTHESIS TECHNOLOGY PAGE 5 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM g 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 flow in the hole such that on the top component side a small amount is on the top pad as well A SMALL AMOUNT not a blob 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 This pc board has parts very close together It may not be clear where a certain resistor or capacitor is We will try to give you a hint for the hard to find parts Locate the 1K resistors 6 and solder into R15 right of U3 R23 by J5 R29 above J1 R32 R34 and R35 by the jack wiring holes Locate the 220K resistors 5 and solder into R1 and R5 by VR2 R12 left of U2 R21 by Q3 and R28 by Q5 Locate the 100K resistors 5 and solder into R7 left of U1 R10 left of U2 R20 beside Q4 R27 by Q6 and R33 right of C4 Locate the 20K resistors 4 and solder into R3 by VR2 R22 below C2 R31 below R22 and R87 right of U1 Locate the 39K resistors 8 and solder into R8 by left of U3 R18 left of U2 and R14 left of U1 PART 2 BOARD WASH 1 Verify all the resistors are in the correct position Verify
14. n order to neatly attach the many wires to the front panel components the wires are soldered in a specific order g UO 4 g Insert the 2 red LEDs through the front of the panel with the longer lead up towards the VR1 From the back facing the rear of the panel this would be to the left After you verify that indeed the longer of the LED leads is to the left cut the 4 LED leads about halfway off Using a pair of needle nose pliers bend a J shape like a fish hook in the ends of each lead LED D1 is the topmost LED n between VR1 and VR2 Untwist the red black lead wire in D1 on the board about 2 times slip a piece of heat shrink tubing over each wire and form a J hook at the end Attach the RED wire in D1 to the left lead of the LED Gently squeeze the two J hooks together and solder In the same manner attach the BLACK wire in D1 to the right lead of the LED Slip the heat shrink tubing as far as it will go towards the back end of the LED and shrink 11 place In a similar manner attach the wires D2 to the other LED Red wire to the left lead and the black wire to the right lead Solder coax in J6 to SQR jack it s a stretch but will reach The inner wire goes to the LEFT lug and the braid goes to the BEVELED lug The TOP lug 1s not connected Solder the Red Black wire J2 to the FM IN jack Red wire to Left Black wire to Beveled Solder the coax
15. o rail not quite but close so resistors R30 and R31 divide down this to a 5V swing The LED drivers are driven from the 2 LFO triangle wave outputs Looking at the fixed LED circuit resistors R17 and R21 bias up Q4 since the collector is grounded to offset the triangle above ground R20 and R17 form an input divider that regulated the current into Q3 Q3 1s just a buffer R19 sets the maximum brightness level of the LED As the triangle wave rises and falls the current sucked by Q3 gradually turns on and off D1 The second section of the LFO is similar to the LFOs in the MOTM 410 The circuit of the basic oscillator 1 nearly identical except we have replaced the pot divider and resistor R20 with an OTA stage U3A An OTA outputs a current which we require to directly drive integration capacitor C7 Resistors R8 and R9 divide the rail to rail square wave down but not that much the still saturates This 1s done on purpose so that the LFO speed is set by bias current into the OTA pin 1 The current comes from simple exponential pair Q1 and Q2 Resistors R1 and set the FM voltage and R5 and set the initial voltage The base of Q1 is summing node and the emitter current is controlled 1n this manner Since the relationship between Vbe and Ic 1s exponential and assuming hfe 1s large so Ic Ie we have an exponential current Q2 is a current mirror since the 2 emitters are
16. stacked metal film cap marked 224 Solder into C7 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 1 and C2 with the stripe away from pad on the board Check to be sure both electrolytic caps have their stripes facing the SAME WAY Wash the board again gently scrubbing both sides Use ONLY warm water SYNTHESIS TECHNOLOGY PAGE 7 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM PART 5 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 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 1s the side where the locking tab goes Locate the 2ea 0748 Solder into U1 and U2 Carefully orient the part such that the notch in the top of the package matches the silkscreen pointing towards the power connector Locate the NE5517 Solder into 03 noticing that 1t points the same direction as U1 and U2 If you are not sure please CALL OR EMAIL F
17. tied together through the same resistor R2 This has one additional stage sine shaper U3B This circuit is also used on the 300 In this case R15 and R16 are carefully selected to provide the exact voltage needed to operate the OTA s input differential pair a certain knee of operation SYNTHESIS TECHNOLOGY PAGE 12 MOTM 390 ASSEMBLY 8 13 02 WWW SYNTHTECH COM The triangle wave 15 warped into an approximation of a sine R22 sets the final output level PRELIMINARY CHECK OUT amp CALIBRATION There are no trimmers on the MOTM 390 Apply power and turn both RATE knobs to tick 6 The LEDS should be flashing but at different speeds Applying a positive voltage to FM IN should increase the rate of the second LFO Adjust the FM pot to verify TROUBLESHOOTING If your MOTM 390 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 of the ICs are pointing the same way and all notches pointing to the left which 1s away from the front panel The NE5517 1s the IC closest to the panel Check EVERY transistor for proper location and SURE that U4 really isa 78105 The 2 red black wires are correctly soldered into D1 and D2 If the TRI outputs correct and the LED s are not working chances are you swapped th
18. ttach 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 g Locate the 6 Switchcraft jacks Notice that from the rear there is a beveled corner This corner is ALWAYS CONNECTED TO GROUND USUALLY WITH THE BRAIDED CONDUCTOR Each jack has a 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 6 jacks lockwashers with the beveled corner in the upper right corner into the 6 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 You are now ready to attach the pc board to the bracket and then wire up to the panel PART 9 ATTACH PC BOARD TO BRACKET g g In the HARDWARE bag locate 4ea 6 32 x 3 8 screws 4ea 6 KEPS nuts and 4ea 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 If the bracket has a protective plastic covering remove 1 first The 6 KEPS nut attaches the bottom of the bracket Note the bracket
19. ything 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 1s also in the README FIRST document that every customer receives with his or her first order If you are unsure of a resistor s value use your trusty DVM to measure it Inserting the wrong resistor in the LFO kit will cause interesting behavior And it s very hard to find the error You will start by soldering in ALL of the resistors Find the RESISTOR bag Find the 390 blank pc board There 1s 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 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 1s to be sure that the part is sitting all the way down on the board Push the leads 1 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 fall
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