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cleaning a tube amp

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(@Anonymous)
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Hi folks, my tube amp is over 40 years old and needs a good clean up... something I've never done before. So how do you clean a tube amp? What products and tools do you use? Anything I should watch out for?

Thanks!


   
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(@stratman_el84)
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Joined: 16 years ago
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Hi folks, my tube amp is over 40 years old and needs a good clean up... something I've never done before. So how do you clean a tube amp? What products and tools do you use? Anything I should watch out for?

Thanks!

First, use a soft-bristled toothbrush and/or paintbrush (small) and canned compressed air available at any computer supply location to clear out the major dust-bunnies, etc. For cleaning controls, pots, and switches use a good quality *lubricated* tuner-cleaner. DO NOT USE WD-40!!! If the cleaner is not lubricated, it'll wash away the grease and will cause the pot/switch to freeze up and/or lose the nice 'feel'. Spray a little cleaner into the pot or switch, and work it through its' range repeatedly. Don't flood the pot or switch excessively, as this can also rinse away the factory grease and leave the pot/switch feeling loose and cause problems. For cleaning tube sockets, use a *non-residue* type tuner/contact cleaner. You don't want any lubricant left behind on tube sockets, as it will attract grime and lead to arcing.

Before you start, make sure the amp is unplugged and make sure to discharge the power supply filter capacitors. They can hold a charge for a surprisingly-long time, and *can* be LETHAL! Also, filter capacitors have a 'memory' of their stored charge, and after a brief discharge to ground, can rebuild a hefty charge without power being re-applied. The safest route here is to attach a clip-lead from the positive end of the large filter capacitor (marked with a '+') to the negative lead/ground, and leave it attached until you're finished. BE SURE to remove it though, before you power the amp back up!

If the amp is 4 decades old, you'll probably want to replace the filter capacitors and tubes, if that hasn't been done.

Good luck!
Cheers!

Strat

[EDIT] Thought I would add that if you plan to pull all the tubes, use a felt-tip pen or marker to number each tube and its' socket so that you can replace them exactly how they were before you started. [/EDIT]


   
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(@Anonymous)
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Topic starter  

Wow, thanks for the detailed answer stratman! I read here http://www.kbapps.com/tubecare.html that WD40 was needed to clean up an amp but I was skeptical about it and thought I would ask for a second opinion. I'm glad I did!

Thanks again! :D


   
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(@stratman_el84)
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Joined: 16 years ago
Posts: 141
 

Wow, thanks for the detailed answer stratman! I read here http://www.kbapps.com/tubecare.html that WD40 was needed to clean up an amp but I was skeptical about it and thought I would ask for a second opinion. I'm glad I did!

Thanks again! :D

You're very welcome! Glad to be of help!

If you'd be so kind, I'd like to take the opportunity to expand a bit on the whole WD-40 subject concerning its' use as a cleaner for tube amps.

The problem with using WD-40 on potentiometers and switches is that WD-40 has a high amount of solvents as compared to silicone lubricant, and will wash away the heavy grease on the shaft and bushings of pots, and on the sliders and other mechanical parts of switches which can cause them at the very least to lose the smooth feel, and can cause them to seize up and become unusable. Even using a proper lubricated type tuner cleaner, caution must be used to not wash away this grease by excessive flooding.

In the case of tube sockets where the contacts have tarnished to the point that normal non-residue tuner/contact cleaner can't remove it, the best procedure is to replace the socket, as the plating on the contacts is thin. In an emergency, as a temporary fix, you can try using WD-40 along with a toothbrush and repeatedly inserting/removing the tube to obtain an acceptable contact surface, but all surfaces sprayed with the WD-40 (including the base and pins of the tube you were using) must be cleaned with non-residue tuner/contact cleaner afterwards to remove the silicone lubricant. High voltage attracts dust, and combined with the presence of a lubricant film, will cause the formation of a layer of grime that can create a path for arcing to occur.

I've spent a lifetime working at some of the largest U.S. aerospace electronics manufacturers as an engineering/R&D technician where I helped to develop as well as write a lot of the technical and service procedures for equipment ranging from aircraft avionics to radar and guidance systems for missiles and high powered radio communication systems for military/defense. I'm not just spouting a personal opinion here with no knowledge or experience to back it up. The article you linked to cited Cesar Diaz the famous amp tech as a source for using WD-40, but I'm willing to bet large amounts that the cite wasn't complete, and if Cesar is as knowledgeable as is reported, he almost certainly uses WD-40 as I've described here.

Cheers!

Strat


   
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(@ricochet)
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Joined: 21 years ago
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As for the contents of WD-40, the MSDS says it's light mineral oil and hydroformed kerosene. No silicone.

"A cheerful heart is good medicine."


   
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(@stratman_el84)
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Joined: 16 years ago
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As for the contents of WD-40, the MSDS says it's light mineral oil and hydroformed kerosene. No silicone.

Of course you're correct, Ricochet. Thanks! Replace the places in my previous post where I said silicone with mineral oil and kerosene residue. My point about it dissolving the grease used as control lubricant, especially in potentiometers, stands though. As does the point about the residue attracting grime, especially with the presence of high voltage.

Cheers!

Strat


   
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(@ricochet)
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Joined: 21 years ago
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It's a great solvent for lots of stuff, a lousy lubricant for most things, doesn't last long as a protectant, but does leave enough residue to catch dirt. I've been known to use it for expediency, but it's not the best stuff for the job for sure.

"A cheerful heart is good medicine."


   
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(@prndl)
Reputable Member
Joined: 18 years ago
Posts: 199
 

Antique (tubesandmore.com) sells a bunch of cleaning supplies for tube amps - primarily DeOxit.

In the old days, contact cleaner or tv tuner cleaner was used all the time, but like WD40, they changed the formula by adding solvents that help clean but cause all kinds of problems.

It is important to seal exposed metal chassis to avoid oxidation and rust. This is usually done with oil. Some paint the chassis with clear polyurethane, but this can be difficult with everything installed.

Some techs re-solder all the joints. Old time repairmen will also test the solder blobs that ground to the chassis with a screwdriver. Bad ones will fall off. Re-soldering them takes a very hot iron, but is very important for proper grounding.

1 watt of pure tube tone - the Living Room Amp!
http://www.naturdoctor.com/Chapters/Amps/LivingRoomAmp.html
Paper-in-oil caps rule!


   
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(@ricochet)
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Joined: 21 years ago
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"Boat anchor" radio collectors will take a "new" nasty old chassis and stick it in the dishwasher, then leave it out in the sun in the driveway to dry out. After this they replace all the caps. Paper ones aren't likely to survive a trip through the dishwasher, but they're not likely to be anywhere near specs after a few decades, either. Tubes run through it would lose markings printed on the glass; you'd need them out to get the sockets clean anyway.

"A cheerful heart is good medicine."


   
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(@stratman_el84)
Estimable Member
Joined: 16 years ago
Posts: 141
 

Allied Electronics has a wide range of contact cleaners, flux removers, tuner cleaners, etc etc. They even stock cleaners "For Commercial Use Only" and cleaners in bulk quantities. Click on an items' "Datasheet" PDF link for detailed info. (You'll need Adobe Acrobat installed)

http://www.alliedelec.com/Search/SearchResults.asp?N=0&Ntt=contact+cleaner&Ntk=Primary&i=0&sid=479683803DD1617F

Cheers!

Strat


   
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