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Best Practices for cleaning vintage amp pots?

Discussion in 'Amp Tech Center' started by SemiHollowGuy, Dec 1, 2015.

  1. SemiHollowGuy

    SemiHollowGuy TDPRI Member

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    Noob to TDPRI.

    Recently became the new (only 2nd) owner of a Dean Markley RM-80-DR. The original owner never took it out of the house and the thing looks literally like it just came off the showroom floor. However a few of the pots are scratchy.

    Is there any special way or cleaner to use to clean the pots? I'm comfortable taking things apart but would like to know what to do once I get there.

    Thx.
     
  2. Blue Bill

    Blue Bill Poster Extraordinaire Ad Free Member

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    Here's how I do it: Use two spray cans, a lubricant, like WD-40, and an electronic cleaner, we used to call it "tuner cleaner", CRC makes several formulas. I think you can get both at HD.

    Use the little hose thingy, start with the lubricant, shoot it right into the little opening on the back of the pot; it should foam up a bit. Work the knob back and forth a few times. Next, flush it out with the cleaner. The idea is to clean it out and leave a little lubricant, but not leave it all gunked up inside, which can attract dust, moisture and future corrosion problems.

    Stuff a paper towel around the pot to catch the stray liquids. Welcome to the TDPRI.
     
  3. jazzguitar

    jazzguitar Tele-Afflicted

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    Tricky. Whether or not the amp looks new, chances are it collected some dust inside.

    Regular use of the amp may cure scratchy pots, though if it does not, Caig Deoxit or a similar cleaner will help. For some time at least.

    Most pots of this type become scratchy soone or later.

    Try moving them a lot and see whether that helps.

    In some circuits there is a DC current through the pots, eg the volume pot on a Fender blackface circuit. This acts as ground for the tube grid and feeds the stray electrons to ground, hence there is a tiny current. It is almost impossible for these not to be scratchy unless they're new.
     
  4. keithb7

    keithb7 Friend of Leo's

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    My understanding is even the humidity in the air will eventually cause corrision inside pots. The cleaner does the trick.
     
  5. Wally

    Wally Telefied Ad Free Member

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    As jazz guitar notes, the first step is to work the pot through its entire range but especially through the area where the scratchiness appears....sometimes this repeated movement polishes the surfaces and the problem disappears. If this doesn't work then a cleaner/lubricant is used...again with movement of the pot through the sweep....rapid repeated movement. If this doesn't cure the problem, one would then suspect bad solder connections at the pot...touch them up and the noise may disappear. If the noise persists, then caps come under suspicion next. If leaked DC voltage from a bad cap is not found on the pot, then one replaces the pot.
     
  6. KevinB

    KevinB Doctor of Teleocity

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    Caig DeoxIT is the best stuff out there.

    You can get it from a local Radio Shack (if you still have a local RS) or from many internet sources.

    [​IMG]
     
  7. bblumentritt

    bblumentritt Tele-Afflicted Platinum Supporter

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    DeoxIT.
     
  8. ultra80096

    ultra80096 Tele-Meister

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    Another alternative I've found works well is John Deere Superlube. When the liquid carrier evaporates, it leaves a bit of Synthetic lube behind. Found that out when I needed something quickly & didn't have any store around that carried Deoxit. Works very well!
     
  9. Doctorx33

    Doctorx33 Tele-Afflicted

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    I certainly wouldn't use WD40, and probably not the john deere stuff. Home Depot sells contact cleaner and Radio Shack sells a contact cleaner that works good, and of course DeOxit if you can find it.
     
  10. BobbyZ

    BobbyZ Doctor of Teleocity

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    A wee bit of Radio Shack tuner cleaner is what I use.
    Oh I know I should get Deoxit like all the grown ups use but this stuff has always done the trick.

    Last winter a friend was having trouble with a pellet stove. A bad potentiometer the factory told him. So he's wondering if I can change it.
    Showed him a pot and where to spray the stuff, that fixed it.

    My kind of fix. I get credited with being not only a nice guy but a smart one too and I didn't have to work on a wood pellet stove.
     
  11. Wally

    Wally Telefied Ad Free Member

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    I have opened up amps and found old news inappropriate lubricant holding on to dirt all over and around the pots. There will even be oil/dirt under the knobs on the outside of the panel. I don't like to have electronics looking like an old oily engine.
     
  12. Johnny Cache

    Johnny Cache Former Member

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    I wouldn't use WD-40 it's not intended for electrical use, nor Liquid Wrench or any of those kind of products intended for mechanics. A good tuner cleaner with lube is all you really need CRC makes a pretty good one and Radio Shack has a some too. Some like Deoxit D5 if you can find it, it's is one of the best.
     
  13. Wally

    Wally Telefied Ad Free Member

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    I have seen an electronic contact cleaner without a lube in it freeze a pot in the time it takes to make two sweeps of the wiper....and no lube will free it up. IF....big IF for me....one must use anything in a pot, use a cleaner/lube made for such a purpose. I use it as a last resort.
     
  14. deytookerjaabs

    deytookerjaabs Friend of Leo's

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    I've been using DeOxit "fader lube" in everything from mixing consoles, to old synths, drum modules and amplifiers for a long time ever since a professor who rebuilt/modified vintage recording equipment turned me on to it in a recording class. On the one hand, it's nice to not have to use it but on the other hand the Fader Lube is great because those knobs you barely touch will be problem free a year later. Just make sure you protect/clear the area around it because it does leave a film.
     
  15. Blue Bill

    Blue Bill Poster Extraordinaire Ad Free Member

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    You're probably right. I couldn't remember the name of the spray I used to have, LPS, I think. These days, I do use WD40, mostly 'cause that's what I have a can of. I figure the rinse with non-residue cleaner washes away the gunk. Works for me, pots I treat this way stay non-scratchy for years.
     
  16. BobbyZ

    BobbyZ Doctor of Teleocity

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    No matter what you use don't use much of it ! A can of Tha Radio Shack or Deoxit should last most people a life time.
    A little dab'll do you. Like Brylcreem !
     
  17. CoolBlueGlow

    CoolBlueGlow Tele-Afflicted

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    WD40 / Liquid Wrench on pots

    Never use household/automotive spray solvents to clean potentiometers. Yes, I know folks have gotten away with it. It is bad practice for the reasons already noted (dust attraction, etc.)

    Beyond that, here's another couple of reasons.

    A fair number of potentiometers, including many used in vintage and modern era Fender contain parts made of nylon. This includes internal wiper assemblies and especially the shafts.

    Most aggressive automotive type cleaner lubricants contain aliphatic (and often aromatic) hydrocarbons. This includes "electric motor cleaner" as sold at automotive box houses, as well as brake cleaner, Liquid Wrench, WD-40, etc. Check the can. If it says "Stoddard Solvent", it has at least some aromatic or aliphatic hydrocarbon present.

    When the type of nylon (Nylon 11) as used in a substantial number of potentiometers (especially vintage) is exposed to aliphatic hydrocarbons, it swells. (Not "melts")

    That swelling is the cause of the mysterious "I cleaned my pots and now they won't turn" syndrome. The nylon shaft has swollen up, effectively reducing the clearance in the sleeve to nil. Frozen control = sad. :confused:

    For common cleaning, sparingly apply a proper electronic cleaner, as noted by others.

    It is a good practice to disassemble a new CTS brand potentiometer and examine the current factory lubrication practice. You will discover that there is a substantial quantity of paste lubricant present. This knowledge will encourage you not to flush/flood a potentiometer with an aggressive solvents. That practice partially dissolves the factory lubricant, leaving the lubricated portion unprotected, and re-depositing remnants of the same on the wiper surface. This leads to future troubles. (Aka the "I cleaned it but it went bad again pretty quick" syndrome)

    CBG
     
  18. Robster

    Robster Tele-Afflicted

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    One thing everyone is forgetting before cleaning pots...

    Blow the dust out of the pots before cleaning. I have an air compressor so all amps get the dust blown out then I turn it down a bit and blow out the pots. I have seen lots of dust come out of some. You can use those little cans of spray air too. Then apply Deoxit and turn the knob at least a dozen times.
    I let that sit overnight so it can drain out of the pot, then shoot them again and let them drain again. Works for me.
     
  19. Tele wacker

    Tele wacker Tele-Holic

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    Buy some electronics cleaner and carefully spray into the opening of the pot. Not a bunch but just a quick "squirt". Turn the pot several turns. I have an air compressor and I use it to blow out any residue. The air compressor air also dries things out inside. Never have frozen a pot and this method has worked every time.
    All you are doing is cleaning out residue on the contacts inside the pot. They pick up "stuff" over time.
     
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