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Hoffman Amps Forum image Author Topic: reusing fender bias pot on hoffman board (pinout)  (Read 2684 times)

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Offline nateflanigan

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reusing fender bias pot on hoffman board (pinout)
« on: July 12, 2010, 08:39:23 pm »
I'm not totally sure on this so I thought I should ask.  I'm reusing the bias pot from a DRRI on my ab763 build, I can't find much in the way of pinout info.  So I'm assuming...

Looking at the back of the pot, with the pins facing down...

pin 1 to 22k resistor
wiper to bias cap
pin 3 to the diode

Does that sound right?

Offline nateflanigan

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Re: reusing fender bias pot on hoffman board (pinout)
« Reply #1 on: July 13, 2010, 09:22:11 pm »
hmmm, how bout can anyone verify which pin on the hoffman bias pot is the wiper?

Studying the schematics it seems like the hoffman bias/tremelo combines aspects of the brown face and black face, I just can't seem to sort it out.  Melting my brain.
« Last Edit: July 13, 2010, 09:56:51 pm by nateflanigan »

Offline sluckey

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Re: reusing fender bias pot on hoffman board (pinout)
« Reply #2 on: July 13, 2010, 10:30:46 pm »
Quote
pin 1 to 22k resistor
wiper to bias cap
pin 3 to the diode

Does that sound right?
That's fine.

Quote
which pin on the hoffman bias pot is the wiper?
Follow the pots/knobs link at the top of this page for a pic of the bias pot. In this pic, pot on the left, wiper is on the bottom, just like in the layout.

Quote
the hoffman bias/tremelo combines aspects of the brown face and black face, I just can't seem to sort it out.
That's right. Maybe this schematic will help.
http://home.comcast.net/~seluckey/Hoffman_AB763.pdf

« Last Edit: July 13, 2010, 10:36:19 pm by sluckey »
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline nateflanigan

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Re: reusing fender bias pot on hoffman board (pinout)
« Reply #3 on: July 14, 2010, 07:22:36 am »
Thanks so much, that schematic definitely cleared things up.  It gets kind of hard squinting at those old fender schematics and toggling between different windows. 

 


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