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MOTM-850 Pedal Interface 

Assembly Instructions & Owner’s Manual 

 

 

 

 

 

 

 

 

 

Synthesis Technology 

6625 Quail Ridge Dr. 

Fort Worth, TX  76180 

(817) 281-7776 

www.synthtech.com 

 

 

 

 

 

Oct. 25, 2001 

Summary of Contents for MOTM-850

Page 1: ...MOTM 850 Pedal Interface Assembly Instructions Owner s Manual Synthesis Technology 6625 Quail Ridge Dr Fort Worth TX 76180 817 281 7776 www synthtech com Oct 25 2001 ...

Page 2: ...2K 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 1ea 620K blue red yellow R11 1ea 100K 1 brown black black orange R16 1ea 82K5 1 gray red green red R17 1ea 16K5 1 brown blue green red R18 IC bag containing the following 5 parts 1ea 2N3904 NPN transistor Q1 1ea LM311N comparator U1 1ea LM78L12 12V TO 9...

Page 3: ...s 1ea 2 wire set 22ga 3 inches red black 1ea 3 wire set 22ga 2 inches orange white gray 1ea 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 4ea small tie wraps Org...

Page 4: ...se 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 sh...

Page 5: ...now 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 start by soldering in ALL of the resistors Find the RESISTOR bag F...

Page 6: ...bove 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 R...

Page 7: ...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 ...

Page 8: ... 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 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 th...

Page 9: ...s 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 bev...

Page 10: ...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...

Page 11: ...that is 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 Solder the coax in J3 to the GATE jack Solder the orange white gray wire in J...

Page 12: ...he other circuitry Dual precision op amp U4 MXL1013 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 M...

Page 13: ...is a VTRIG rises to 12V when the comparator trips and a simple transistor inverter Q1 R1 R8 provides STRIG Q1 also is a 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 and a separate offset trimmer pot of 5...

Page 14: ...ections around See Figure 2 Since the pedal pot is 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 03...

Page 15: ...d 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 straight into R24 Since the output impedance of the CV pedal i...

Page 16: ...ferent 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 5V 0 0 TO 5V 0 Doesn t matter OFFSET reading 5V 2 5V 2 5V to 7 5V 5V 2 5V 2 5V to 2 5V 2 5V 2 5V 2 5V to ...

Page 17: ...xceeds 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 to the left on the scale Is this making ANY sense at all Why am I going on and on about this Because you can set ...

Page 18: ...is 12V When GATE is ACTIVE the GATE output is 0V 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 0V when inactive and 12V when active That sums up how the module itself functions How it s actually used in your MOTM system i...

Page 19: ...ge 7 5V to 7 5V nominal GATE voltage 12V max 0V min MIX input range 7V to 7V nominal CONTROLS RANGE Sets the over pedal response range OFFSET Sets the DC offset of the pedal GATE Sets the GATE threshold MIX Attenuates the signal applied at MIX IN GENERAL Power Supply 15VDC 10 ma nominal 15VDC 15 ma nominal Size 1U x 5U 1 72 x 8 72 44mm x 221 5mm Depth behind panel 2 375 inches 60 3mm ...

Page 20: ... 1 1 2 ROLAND 2 3 YAMAHA OPEN FOR 100K POT PEDAL MIX IN RANGE VR4 100K L VR1 100K L R24 332K 1 2 3 1 2 3 T R S J1 112B J2 3 2 1 8 4 U4A LT1013 12V 12V C10 0 1M R14 10K R15 715K 1 R13 47K5 1 R12 47K5 1 1 2 3 4 JP1 MTA 156 15V 15V C7 10M C8 10M L1 FERRITE L2 FERRITE R8 10K C3 10M 25V C4 0 1M 12V 12V I 3 G 2 O 1 U2 LM78L12 15V I 2 G 1 O 3 U3 LM79L12 15V 1 2 POS GATE 2 3 MOOG STRIG 12V C1 0 1M 12V C9 ...

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