[sdiy] Cleaning amp potentiometers

[Gorka Garcia]

Hey!!!

Thanks!!! I think that is very probably another cause of the problems of the amp I am trying to give back to life.

I read that these amps heat up a lot, causing some solderings to melt, as you suggest. I thought of putting a PC ventilator on the back to give it a longer life in the future... seen it done here: http://www.pisotones.com/Ventilador/Ventilador.htm (sorry, in spanish...). What do you think?

Thanks again for the tip,

Gorka


--- ChristianH <chris at scp.de> wrote:

From: ChristianH <chris at scp.de>
Date: Wed, 05 Oct 2005 11:31:34 +0200
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Cleaning amp potentiometers

Hi Gorka,

I recently fixed a Valvestate for our guitar player. In this case those
nasty noises didn't originate from bad pots or jacks, but a bulky power
resistor on the board had become loose in its soldering pads. 

Since these large resistors (IIRC 4 of them in the power stage) are
mounted with no other support than the soldering pads, I'd expect this
to be a common source for scratchy noises, especially in a vibration
prone environment as a guitar combo. Resoldering all large resistors
fixed it :-)

regards
Chris



On Wed, 5 Oct 2005 01:59:37 -0700 (PDT) Gorka Garcia
<torpedo at demadrid.com> wrote:

> A friend came home last week with a Marshall amp from the 90's (one of those Valvestate amplifier, for those who play guitar) with scratchy potentiometers asking if I could do anything to get them back to their normal state. 
> 
> So, what is the best way of cleaning them? Contact cleaner? Is it worth it or would they become scratchy again soon?
> 
> The type of potentiometers are alpha pots but with a longer shaft. Being so small I thought it might be difficult to get the dust out of them without opening them and possibly breaking them. What do you think? suggestions? any tips?
> 
> Thanks in advance and best regards,
> 
> Gorka



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