Mod K-700 Instructions Manual Download Page 1

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Use these instructions and your vintage Fender guitar amplifier to learn:

How to convert the “Bass Instrument” channel of a Bassman amp into a tremolo
effect for the “Normal Channel”.

BASS TO TREMOLO CONVERSION KIT (K-700)

100k

INTENSITY

50k-

220k

.01

www.modkitsdiy.com

Summary of Contents for K-700

Page 1: ...itar amplifier to learn How to convert the Bass Instrument channel of a Bassman amp into a tremolo effect for the Normal Channel BASS TO TREMOLO CONVERSION KIT K 700 1 Copyright 2011 by modkitsdiy com...

Page 2: ...f Contents Safety 3 Parts List 4 5 Tools 6 Soldering Tips 7 8 Preliminaries 9 Test Points 10 Bass to Tremolo Modification 11 24 2 Style A 12 17 Style B 18 23 Schematics 12 18 Terminal Strip Mounting T...

Page 3: ...nt Tube amps operate at high voltages which have the potential to kill Only work on an amp when you are wide awake and sober Please make sure you do the following before opening your amp Turn the powe...

Page 4: ...022 F capacitor 022 F 630V 01 F 630V R A100K 3 100k W resistor R A1M 2 1M W resistor brown black green gold 1M R A3M 1 3M W resistor orange black green gold 3M R A8D2M 1 8 2M W resistor grey red green...

Page 5: ...r R VC3M RA 1 3M potentiometer reverse audio taper W SC 11 1 input jack P H35 242 1 DPDT slide switch 5 S W809L 15 ft 20 AWG solid core hook up wire white P 0501H 3 5 lug terminal strip 3rd lug common...

Page 6: ...ucing 25 40Watts This will allow you to do some precise soldering of circuit components and wires do not use a soldering gun for soldering of electronic circuits 4 Solder 60 40 rosin core solder 5 De...

Page 7: ...tentionally burn any wires in the vicinity of the soldering iron De soldering Tip 2 If necessary add new solder to the connection point to help it become a liquid 1 Heat up the connection point until...

Page 8: ...ur work and allow the solder joint to cool The solder joint should be shiny and smooth after solidifying Cut off any excess wire or component leads with cutting pliers Clean the soldering iron s tip b...

Page 9: ...place ON STANDBY When the amp is open Follow the one hand rule and use a volt meter with alligator clips to measure for high voltage at several test points The one hand rule pictured above is a safety...

Page 10: ...tage should have been drained TP 3 This is the anode side of a solid state diode TP 4 TP 5 These test points are the cathode pins of the preamp tubes It is not a bad idea to check these two pins on ea...

Page 11: ...ving the following characteristics a The amp has 3 preamp tubes including two 7025 12AX7 tubes and one 12AT7 tube b The first tube is connected to the Bass channel input c The second tube is connected...

Page 12: ...1 1M 68K 68K 1 5K 5 100K 100K 500p 047 1 8 2K 250KA BASS 250KA TREB 1MA VOL 6 7 8 V1 DEEP 100K 375 VDC 220K 2 1 BASS 047 1M 375 VDC FENDER BASSMAN 100 PREAMP BEFORE MODIFICATION 047 0047 1 2 3 V2 1M 6...

Page 13: ...d ground 3 Disconnect the resistor from the deep switch 4 Disconnect the volume pot connection at V1 pin 7 5 Disconnect the volume pot ground connection 6 Disconnect the capacitor from the volume pot...

Page 14: ...6 5 4 3 2 8 9 V1 V2 Step 4 Mount new front panel controls for tremolo circuit 1 DPDT slide switch 2 3M pot in place of the volume pot 3 50k pot in place of the treble pot 4 input jack in place of the...

Page 15: ...r wire connected from V1 pin 8 to V2 pin 8 Each instruction line number here corresponds to the numbers on the drawing where missing components are outlined 1 1 2 2 2 2 2 3 4 4 375V Power Supply Line...

Page 16: ...4 5 1 Connect the 3M resistor from terminal 1 to 4 2 Connect a 1M resistor from terminal 2 to 4 3 Connect a 1M resistor from terminal 4 to 5 TOP VIEW SIDE VIEW 4 Connect the opto coupler as shown Mak...

Page 17: ...1 pin 7 with two wires to T1 5 and the circuit board where the two 01 F feedback capacitors are connected together 4 Connect V1 pin 8 to T3 4 Circuit Board Connections 1 Connect T2 1 to the 8 2M resis...

Page 18: ...1M 68K 68K 1 5K 750 100K 100K 330p 1 047 8 2K 250KA BASS 250KA TREB 1MA VOL 6 7 8 V1 1 5K 5 DEEP 100K 400 VDC 220K 2 1 BASS 01 1 220K 400 VDC 1 2 3 V1 2 7K 22 220K 6 7 8 V1 100K 22 8 2M 500 VDC 100K...

Page 19: ...deep switch connections to the circuit board and ground 3 Disconnect the volume pot connection at V1 pin 7 4 Disconnect the volume pot ground connection 5 Disconnect the treble pot connection to the b...

Page 20: ...l leave the last of the four pots mounted but completely disconnect it from the circuit Disconnected BASS 2 1 FOOTSWITCH 3 M E G 5 0 K SPEED INTENSITY 1 7 6 5 4 3 2 8 9 1 7 6 5 4 3 2 8 9 V1 V2 1 7 6 5...

Page 21: ...1 2 2 2 2 2 2 3 3 4 4 4 5 5 6 BASS 2 1 FOOTSWITCH 3 M E G 5 0 K SPEED INTENSITY 1 7 6 5 4 3 2 8 9 1 7 6 5 4 3 2 8 9 V1 V2 1 7 6 5 4 3 2 8 9 1 7 6 5 4 3 2 8 9 V3 V4 1 0 0 K 022 F 630V Step 7 Add new c...

Page 22: ...nnect the 3M resistor from terminal 1 to 4 2 Connect a 1M resistor from terminal 2 to 4 3 Connect a 1M resistor from terminal 4 to 5 TOP VIEW SIDE VIEW 4 Connect the opto coupler as shown Make sure th...

Page 23: ...tors connect 3 Connect a wire from the circuit board connection with V3 pin 6 to T3 1 4 Connect a wire from the circuit board connection with 470K resistor to T3 5 as shown bias diode not shown in act...

Page 24: ...ds are held in to place by several self tapping screws which give us a way to mount the terminal strips without drilling new holes in the chassis Determine the best screws to use for mounting each ter...