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Hoffman Amps Forum image Author Topic: Gibson GA40 LP on bench  (Read 3074 times)

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Offline Madison

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Gibson GA40 LP on bench
« on: August 14, 2013, 08:42:45 am »
Just wondering if the tremolo frequency pot is normal or reversed on these?
I mean, it works in reverse as I rotate it.
IOW dimed the speed is slowest.

Amp is all original, even the tubes.
Did a full cap job, sounds superb and pretty darn loud.
Think I like it better than a 5E3.....and I LOVE 5E3s!

Too bad it is a bear to work on!
The put most of the caps under the board.grrrrr!

Offline sluckey

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Re: Gibson GA40 LP on bench
« Reply #1 on: August 14, 2013, 09:33:52 am »
Quote
Just wondering if the tremolo frequency pot is normal or reversed on these?
I mean, it works in reverse as I rotate it.
IOW dimed the speed is slowest.
If you want it to be slowest when rotated max CCW, then move the wire on the outer lug to the other outer lug.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Madison

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Re: Gibson GA40 LP on bench
« Reply #2 on: August 14, 2013, 07:12:16 pm »
There are only 2 lugs on that pot.
Tried reversing the wires but , as I suspected, no change.
Thanks.

Offline Willabe

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Re: Gibson GA40 LP on bench
« Reply #3 on: August 14, 2013, 10:01:46 pm »
There are only 2 lugs on that pot.

What? Since when does a pot, which is a variable resistance, have only 2 lugs?

Can't be.


                Brad      :think1:   

Offline eleventeen

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Re: Gibson GA40 LP on bench
« Reply #4 on: August 14, 2013, 10:10:17 pm »
Might have been cut off at the factory..? If so, you'd have to try to solder to the rivet on the little piece of bakelite where the lugs usually come out. Dicey.

Offline PRR

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Re: Gibson GA40 LP on bench
« Reply #5 on: August 14, 2013, 10:47:58 pm »
It wants to be a Reverse Audio taper.

A hack is to use a Normal Audio taper, use the other side, let the knob work "backward".

Which way is backward? Look at the volume control on a radio etc. Now find an old-fashioned gas stove. Those knobs turn the other way. It's arbitrary.

Offline Madison

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Re: Gibson GA40 LP on bench
« Reply #6 on: August 16, 2013, 08:07:38 am »
Slapped a 3M RA pot in there.
Works good enough to R&R.
Customer was very pleased, so was I.
Nice amp.

Offline HotBluePlates

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Re: Gibson GA40 LP on bench
« Reply #7 on: September 15, 2013, 11:01:24 pm »
Was your version the one with 2x 5879's & 6V6's? Just a single tone control?


 


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