What types of solvents are okay to use in an older tube amplifier chassis? (Seeburg SHFA2)

Nov 11, 2018
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#1
I have been repairing electronics for a little over a year. I have recently been tasked with repairing a couple of old Seeburg SHFA2 amplifiers. They are filthy. I can see a tech has been in the chassis before. Some of the wax caps have been replaced with newer(still 20-30 years old) Nashville caps, but many of the original caps are present. Of course the ESR values are measuring through the roof, so they will all need to be replaced. One of the tubes is tired (12AX7A), and of course I can't really test the other two types of tubes(6973, 6BJ6) as the tube testers that I have don't seem to contain the test settings, nor can I find them(yet). As this is my first tube based amp repair, I thought it may be a good idea to find a forum(that's you) where this tech is not considered dead. Right now, I need to clean the chassis, replace the caps, finish testing the tubes, then give a thorough inspection of the chassis. All before I even think about powering this dinosaur up. I normally use contact cleaner, D5, Faderlube and on occasion WD-40. This has produced the best results in solid state amps(antiquated). However, this chassis is filthy enough that I feel it needs a thorough cleaning, yet I don't want to remove everything from the chassis. He wants this done in a timely manner and I only have a couple more weeks. Also, I am concerned there may be a little more heat in this chassis due to the vacuum tubes and call me crazy, but it just seems that shooting something akin to brake cleaner into a chassis that contains fabric covered transformer wires might not be the brightest of ideas. These appear to be Bakelite sockets. Any ideas on the least destructive way to clean the chassis without damaging the wiring would be greatly appreciated. Also, any information on test settings for either of the above mentioned tubes(using the Hickock 799 or Jackson 715 testers) would be just peachy as well. Thanks.
 

Uk Paul

Member Sponsor
Sep 27, 2012
320
10
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UK
#2
Hi and sorry you have not had a reply to your question here..
It is a specialised area that may be better suited to DIY Audio.com, but in an attempt to help I have found IPA (Isopropyl alchohol) to be very useful over the years, but maybe you use this already. I often use a foaming antistatic cleaner in spray can too for less aggressive applications, thinks it is called Ambersil iirc.. Small air compressors useful too..

Good luck!
Rgds,
Paul.
 

DonH50

Member Sponsor & WBF Technical Expert
Jun 23, 2010
3,558
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Monument, CO
#3
Flux remover spray will peel about anything off. A friend of mine used to wash old amps out with water and dish detergent, rinse, and bake in an oven at 125 degF for a few hours. But there were plenty of times I had to help repair the damage after his washes...

I would not use WD-40. It tends to leave a residue and is flammable. There are some carb cleaners that might work...
 

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