Removing the tremolo circuit from a Hoffman AB763

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LooseChange
Senior tube assistant
Posts: 211
(3/2/04 7:23 pm)
 Removing the tremolo circuit from a Hoffman AB763
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 I want to remove the Tremolo circuit from a Hoffman AB763 circuit board. Can I connect the .1 mf cap coming from pin 6 on V4 (the plate of the mix stage) directly to the 220k resistor? Do I keep the 47k resistor to ground? Do I change the value? Eliminate it?? Other circuits without the trem seem to direct to the PI. Thanks for the help!
 
HotBluePlates
I only work on Fender's
Posts: 700
(3/2/04 7:42 pm)
 Re: Removing the tremolo circuit from a Hoffman AB763
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 Yes, you can.
V4 pin 6 runs to a 100k resistor and .1uF cap. The cap is also connected to a 47k resistor to ground. The .1uF is already connected under the board to the 220k mixing resistor, so you only need to disconnect/remove the 47k resistor. You can then also remove the associated trem circuitry.
 
LooseChange
Senior tube assistant
Posts: 212
(3/2/04 10:27 pm)
 Re: Removing the tremolo circuit from a Hoffman AB763
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 What is the 47K intended to do??
The signal chain never enters the tremolo circuit.
 
GroundhogKen
Forum Moderator
Posts: 2304
(3/3/04 8:45 am)
 Re: Removing the tremolo circuit from a Hoffman AB763
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 What are you guys talking about?

The Hoffman AB763 has bias vary tremolo.

To remove it: just take out the V5 circuitry and connect node 11 (the junction of the two 220K power tube input resistors) to node 12 ( negative bias ).


V4 is the reverb return/mixing circuit. You not trying to remove the entire reverb/tremolo channel are you?


Ken
 
LooseChange
Senior tube assistant
Posts: 214
(3/3/04 11:07 am)
 Re: Removing the tremolo circuit from a Hoffman AB763
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 Ken,
I was just concerned about that 47k resistor that goes to ground in series with the .1 mf coming from the plate of V4 pin 6. That is the Mix of the reverb and the dry signal. Yes I know I need to move the Bias supply off the trem pot.
Thanks!
 
 
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