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Locate the 22K1 1% resistors (4) and solder into R19 (by Q5), R20 (by L2), R24 (next 
to Q5) and R50 (by C11). 

 

 

Locate the 10K resistors (4) and solder into R25 (by Q7), R45 (by Q2/Q3), R47 (by 
Q8) and R49 (by Q10). 

 

 

Locate the 18K resistors (3) and solder into R17 (next to R49 that you just did), R27 
(by J1) and R29 (2 over from R27). 

 

 

Locate the 2K2 resistors (3) and solder into R21 and R22 (by C3) and R18 (by Q9). 

 

 

Locate the 120K resistors (2) and solder into R9 (by TP2) and R13 (by Q8). 

 

 

Locate the 51K1 1% resistors (2) and solder into R7 and R8 (by U1). 

 

 

Locate the 6K8 resistors (2) and solder into R26 (by Q1) and R30 (close to SW1). 

 

 

Locate the 1K 5% resistors (2) and solder into R34 and R37 (by C7/C6). 

 

 

Locate the 47K resistor (2) and solder into R15 (by SW2B) and  R32 (behind VR2).  

 

 

Locate the 3K3 resistors (2) and solder into R38 (by Q9) and R44 (by C11/C12). 

 

 

Locate the 150K resistors (2) and solder into R39 and R40 (by C10). 

 

 

Locate the 200K resistor and solder into R10 (by TP2). 

 

 

Locate the 1K2 resistor and solder into R23 (by J4). 

 

 

Locate the 470K resistor and solder into R12 (by C12). 

 

 

Locate the 54K9 1% resistor and solder into R16 (by Q1). 

 

 

Locate the 470-ohm resistor (look closely!!) and solder into R31 (by VR2). 

 

 

Locate the 15K resistor and solder into R36 (by SW1). 

 

 

Locate the 47-ohm and solder into R48 (by Q8). Leave the Tempco resistor for a 
later step

 

After soldering all the resistors wash and dry the pc board.  
 
PART #2: Soldering the ICs & Misc parts 
 

SYNTHESIS TECHNOLOGY 

 

PAGE 

6

 

MOTM-485 ASSEMBLY 8/11/05 
WWW.SYNTHTECH.COM

 

Summary of Contents for MOTM-485 GX-1 Diode VCF

Page 1: ...MOTM 485 GX 1 Diode VCF Assembly Instructions Owner s Manual Synthesis Technology 6625 Quail Ridge Dr Fort Worth TX 76180 817 498 3782 www synthtech com Aug 11 2005...

Page 2: ...45 R47 R49 3ea 2K2 red red red R18 R21 R22 3ea 18K brown gray orange R17 R27 R29 2ea 120K brown red yellow R9 R13 2ea 51K1 1 green brown brown red R7 R8 2ea 47K yellow violet orange R15 R32 2ea 6K8 bl...

Page 3: ...t Board Mounting bracket Wire bag containing the following 10 wires 1ea long RG 174 coax J4 2ea short RG 174 coax J5 J6 1ea 2 wire set 22ga white black long J3 1ea 2 wire set 22ga orange white long J1...

Page 4: ...er Fingernail brush for washing off the organic flux Old towel for blotting dry pc board For more information of tools used and suggestions see the MOTM FAQ and Tutorial pages at http www synthtech co...

Page 5: ...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...

Page 6: ...into R34 and R37 by C7 C6 Locate the 47K resistor 2 and solder into R15 by SW2B and R32 behind VR2 Locate the 3K3 resistors 2 and solder into R38 by Q9 and R44 by C11 C12 Locate the 150K resistors 2...

Page 7: ...tch on the white silkscreen symbol Locate the CA3086s 2 and solder into Q7 and Q10 match the notches Locate the BC550C transistors 3 and solder into Q3 Q4 and Q9 The flat side of the transistor matche...

Page 8: ...c caps They solder into C4 and C5 by U1 Locate the 3M3 non polar cap and solder into C9 by J2 Locate the 33 f non polar cap Solder into C6 Locate the 10 f non polar caps 2 Solder into C7 and C8 Locate...

Page 9: ...should be tightened all the way back then rotated turn looser This allows the stress of mounting to be on the threads of the bushing not pressing against the pot body itself Locate the WIRE bag The M...

Page 10: ...hten 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 7...

Page 11: ...lugs of the DPDT switch the set nearest the pcb Orange on the top Gray on the center and White on the bottom lug Now repeat with the 3 wires in SW2A soldering to the upper set of 3 lugs Use a tie wrap...

Page 12: ...rovided in one module For the purposes of adapting the filter core to patchable modular use the original circuit has been updated to a MOTM voltage control front end for 1V Octave frequency as well as...

Page 13: ...hould then be apparent that a bipolar transistor in this case N P N junction devices can act as diodes if one junction is left unused traditionally the collector Thus the bases of our NPNs become anod...

Page 14: ...aking R47 alone provides negative feedback it is the rest of the parts that attenuate the signal that R47 couples back into the filter from the source negative side If negative feedback decreases the...

Page 15: ...ss filter save for that region where the input signal is close to the cutoff frequency at which point it assumes a bandpass within the bounds of Q PRELIMINARY CHECKOUT TROUBLESHOOTING The first thing...

Page 16: ...maha overall design and topology the GX 1 was a controlled environment The waveforms were limited the amplitudes under tight control and many hours were spent in trimming remember this thing cost like...

Page 17: ...nce The trimmer TP1 CV OFFSET is like the FREQ panel knob in parallel It allows you to set the default center frequency of the module for a given FREQ pot setting For example you may prefer bass sound...

Page 18: ...1000 ohms nom Frequency Range 80Hz 6Khz nom CONTROLS FREQ sets filter cutoff frequency RES sets resonance CV MOD reversing attenuator for filter cutoff GENERAL Power Supply 15VDC 8ma 15VDC 15 ma Size...

Page 19: ......

Page 20: ...5V VR2 100KL C4 0 1M R10 200K TP2 20KTP CV OFFSET R15 47K 15V R26 6K8 R50 22K1 15V Q1A Q1B Q1C Q1D THAT340 1 2 3 5 6 7 8 9 10 12 13 14 15V R48 47R 15V SW2 HP LP 6 7 8 Q10C 9 1 0 1 1 Q10D 2 3 1 Q10A 4...

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