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Hoffman Amps Forum image Author Topic: Biasing a Fender Princeton Recording Amp - Ideas?  (Read 7305 times)

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Offline newguitarsmell

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Biasing a Fender Princeton Recording Amp - Ideas?
« on: January 27, 2019, 10:08:06 pm »
Schematic

Offline newguitarsmell

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #1 on: January 27, 2019, 10:10:24 pm »
Rest of the schematics

Offline sluckey

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #2 on: January 27, 2019, 10:40:29 pm »
Instructions are on the schematic.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline newguitarsmell

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #3 on: January 28, 2019, 01:06:22 am »
Now I see it!
Thanks SLUCKEY!!
Now to find it on the TZ board...
« Last Edit: January 28, 2019, 01:37:40 am by newguitarsmell »

Offline newguitarsmell

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #4 on: January 30, 2019, 12:39:29 pm »
I have looked and looked and see no bias pot.. Can anyone else find it on the schematic and let me know? Why would Fender make you remove auxiliary boards to rebias an amp?  :cussing:

Offline sluckey

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #5 on: January 30, 2019, 01:16:44 pm »
Bias instructions... page 6 location A3
Bias schematic... page 2 location A1
Bias pot location... page 5 location C3

A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline shooter

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #6 on: January 30, 2019, 01:43:07 pm »
Quote
page 6 location A3
sometimes I miss the days when everybody talked like this   :laugh:
Went Class C for efficiency

Offline sluckey

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #7 on: January 30, 2019, 02:05:23 pm »
Let's see how many get it! :wink:
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Willabe

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #8 on: January 31, 2019, 08:54:57 pm »
I have looked and looked and see no bias pot.. Can anyone else find it on the schematic and let me know?

Why would Fender make you remove auxiliary boards to rebias an amp?  :cussing:

Don't feel bad, I can't see the schematics clearly. If I enlarge them they get fuzzy. 

It's might be/probably is a type of pot that has no shaft coming out of it, made for PC boards.

You'll find it. 

I think it's by TP7 on page 5? 
« Last Edit: January 31, 2019, 08:57:01 pm by Willabe »

Offline newguitarsmell

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #9 on: February 04, 2019, 10:12:53 pm »
I found it - biased the amp and it sounds fantastic! Thanks all!

Offline beeba

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #10 on: April 29, 2020, 09:41:46 am »
Hello,
i can't see correctly what is noticed for the bias instructions ...
Do you have schématics with greater definition ?
I can't read the value of R43 on power supply board too ...1K ohms 3w ?
Thank you
regards

Offline pdf64

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #11 on: April 29, 2020, 09:58:46 am »
Have you tried clicking on the thumbnail?
Whatever, set to achieve 40mV at TP39.
Pedantic sematicists be warned; the phrase ‘bias current’ is used, shame on you, Fender  :cussing:
« Last Edit: April 29, 2020, 10:01:48 am by pdf64 »
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Offline sluckey

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Re: Biasing a Fender Princeton Recording Amp - Ideas?
« Reply #12 on: April 29, 2020, 10:39:42 am »
I can't read the value of R43 on power supply board too ...1K ohms 3w ?
Schematic says FP1K 1W
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

 


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