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  1. #1

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    Hi all -

    I was bequeathed an old Epiphone amp. Sounds fine, but I cannot move/adjust the dials! They are corroded shut/unmovable. How can I safely free the dials?

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  3. #2

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    If it's that old and fuggedy-ubbety most bench techs would power-up using a light-bulb limiter or Variac. If you don't have that stuff strongly consider not powering up.

    If the pots are stuck you normally would need to replace those pots.

    While you're at it, pay attention to whether the filter caps have given up the ghost.
    Same goes for circuit capacitors.

    And if it has an old-style two-prong power cord upgrade to a modern three-prong grounded cord, with removal of the 'death capacitor' at the same time.

    Here's hoping a gem awaits at the end of the trail!

  4. #3

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    Pitch it and get a digital amp. It will save you money and save your back.

  5. #4

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    Sam is right, that should go to an amp tech to be checked out. Most likely the potentiometers need to be replaced. Plugging it in and turning it on may not be safe (think fire, electrical shock or just doing more damage that has to be fixed).

  6. #5

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    Be very careful with anything electrical

    what everybody else said : take it to an amp tech

    don’t even turn it on until he works on it
    iy may cost a little money but if it was bequeath to you show the donor respect and get it repaired

    and then play the living daylights out of it

    good luck

    BigMike

  7. #6

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    You'll likely need to spend a few hundred dollars getting that thing in good working order. If the pots are frozen, then most of the other components may need replacing. New capacitors, new pots, etc will cost some money, mostly labor charges, but it may be worth it. I think you need to either spend the money or just send it to the landfill. You should not use it as it is, it's going to be dangerous, even if you have good fire insurance.

  8. #7

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    You may try some electrical cleaner/lube on the pots to see if they can be freed up.

  9. #8

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    Which amp? Got any pics?

    I know a guy who could take care of it for you in the Omaha area. There are still a lot of old electronic geeks around.

  10. #9

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    Quote Originally Posted by sgosnell
    You'll likely need to spend a few hundred dollars getting that thing in good working order. If the pots are frozen, then most of the other components may need replacing. New capacitors, new pots, etc will cost some money, mostly labor charges, but it may be worth it. I think you need to either spend the money or just send it to the landfill. You should not use it as it is, it's going to be dangerous, even if you have good fire insurance.
    Every part in it is the same age and has been through the same stresses. So it’s highly unlikely that the other working parts are in great shape. But the condition of the cabinet is as yet undescribed. If the cabinet, its covering and fittings are in decent shape (especially if it looks cool), I’d consider adapting it for a more modern chassis and using a good new speaker. There are so many nice little heads now that at least one should be easily insertable. Swapping in a good used chassis is also a good option that requires only the patience to find a suitable one and the ability to do a little woodworking.

  11. #10

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    Don't throw it out, C,
    Get some PB Blaster if there are no significant plastic/rubber parts in the switches. Pull off the old knobs and sparingly spray the pots over a period of time until free. It dissolves the rust. If there are plastic/rubber parts in the switches(unlikely), buy CRC electronic cleaner which will take longer but also works. I hope this helps you.
    Play live . . . Marinero

  12. #11

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    Quote Originally Posted by Marinero
    Don't throw it out, C,
    Get some PB Blaster if there are no significant plastic/rubber parts in the switches. Pull off the old knobs and sparingly spray the pots over a period of time until free. It dissolves the rust. If there are plastic/rubber parts in the switches(unlikely), buy CRC electronic cleaner which will take longer but also works. I hope this helps you.
    Play live . . . Marinero
    The problem with this approach on severely rusted or corroded pots and switches is that the foreign material not only dissolves but also remains behind where the solvent has evaporated. So it can coat the windings, shaft supports etc with solids if it gets inside the pot or on switch contacts and pivots, causing more problems than it solves.

    Here’s a good article on restoring a severely corroded original LP pot. It gives a good idea of the work and difficulties of doing so. Restoring and keeping the original pots will maintain the value of an otherwise all original and valuable vintage guitar. But on an old amp like this, the odds are that everything from the pots to the transformers will be similarly affected to some degree. If the amp has sufficient value in original form, it may be worth the work to restore it right. But even one pot can take a lot of work. Worse, every tiny piece you touch is fragile and prone to breakage (eg the tabs that secure the pot case).
    Last edited by nevershouldhavesoldit; 10-28-2021 at 12:33 PM.

  13. #12

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    Quote Originally Posted by Chas350-t
    Hi all -

    I was bequeathed an old Epiphone amp. Sounds fine, but I cannot move/adjust the dials! They are corroded shut/unmovable. How can I safely free the dials?

  14. #13

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    Before I retired as a electronic technician my time was billed out at $150 / hour. I was paid $50.

    If I were to take on this restoration project it would be at least a day (8 hours). Replace pots, electrolytic caps, power cord and lot's more.

    If there is enough corrosion to freeze the pots then the tube sockets may need to be replaced also.

    Labor to start would be $400 plus parts. The total cost could be $600 - $1000.

    In my opinion not worth it.

  15. #14

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    OP please do not just try some cleaner spray and plug it in.
    Heed the warnings from another “old electronic geek”/ex-ET/Extra Class ham with 55+ years of tube fun.
    Frozen pots Says to me there’s more rot (technical term))) under the hood. It takes some abuse like being left in a humid place, not regularly serviced, lots of dust, maybe even water to freeze pots. Gotta be more damage there.
    I have to agree with BBguitar. It’s going to be some money.
    You of course can only say if it’s worth it.
    jk


  16. #15

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    What Epiphone amp is it? Got some pics? Old Epi tube amp? Or solid state? How old is old?

    You said it sounds fine, so it’s playing and didn’t blew up on ya I guess.

  17. #16

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    OP says it sounds fine. Is that surprising given the state of the pots?

    How many pots are we talking about?

    I'd be inclined to try to properly clean or replace a few. There are videos showing how to do these things.

    Don't forget to make sure the amp is unplugged and the caps are discharged. If you don't know what that means, don't open the amp. There is a real safety issue.

    Once you're safely in there, it may be just some straightforward unsoldering and soldering.

    At that point, you'll still have a fragile old amp with a likelihood of other problems, but it shouldn't sound any worse, and it will be adjustable.

  18. #17

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    Too bad the OP is not reacting anymore……