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Scratchy pots...is this something that would stop you from buying a used amp?

Discussion in 'Amps [BG]' started by jfh2424, Jan 25, 2014.


  1. jfh2424

    jfh2424

    Joined:
    Jan 10, 2009
    Location:
    Montreal, Quebec Canada
    Hello, I am interested in purchasing an amp but the pots are "scratchy", according to the owner. I won't be able to try it out before I buy it. I am not a tech guy, I don't really know how pots get scratchy or how to resolve these issues.

    Would this stop you from purchasing the thing? Also, could I solve this problem myself? Any ideas what may have done for pots to be scratchy?

    Thanks for your input, it is appreciated!
     
  2. beans-on-toast

    beans-on-toast Supporting Member

    Joined:
    Aug 7, 2008
    This happens to all amps with time. They need service. A scratchy pot can often be fixed by cleaning and lubricating the inside of the pot with a product such as Deoxit. If that doesn't resolve the problem, it could be a leaky capacitor in the signal path.

    Any used amp should be seen by a tech. Consider this additional cost parch of the purchase price. They can clean and lubricate all the necessary bits and bring it up to spec. A gigging amp should be seen by a tech at least every 1-2 years.
     
  3. Jim C

    Jim C

    Joined:
    Nov 29, 2008
    Or:
    You can buy a used, quality, old school transistor amp; run it hard for 20 years and only clean the pots and jacks and hope things go well. I have had this happen with 2 Acoustic heads (450 & 370), 2 Peaveys, 1 transistor Ampeg, and a small GK amp. Simply bullet proof when not abused.

    Tube amps will need some TLC and I have no experience with longevity with the new micro amps.

    I do agree with Beans in theory and on the pro level, but the cost of labor for a check up and minor parts makes many used amps a poor investment over buying new with a warranty.
     
  4. Jerry Ziarko

    Jerry Ziarko Supporting Member

    Joined:
    Feb 23, 2003
    Location:
    Rochester, NY
    Not really. Pots can build up corrosion from being in a static position over time. Sometimes moving them several times completely from zero to ten cures the issue. On a side note, even if you don't use the effects loop on your amp, run a 1/4" plug in and out each jack from time to time to also the build up of corrosion. As far as a bi-yearly check up, I sold and amp ( GK 400RB) a couple of weeks back that I had since the mid 80's that not only had never been to the doctor, but performed as good as the day I got it. Sometimes, if it ain't' broke, don't fix it.
     
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  6. CrashClint

    CrashClint I Play Bass therefore I Am Supporting Member

    Joined:
    Nov 15, 2005
    Location:
    Wake Forest, NC
    No, I keep a can of tuner cleaner/lubricant on hand and if moving the pot full range a couple times doesn't fix the issue I will open the cover and carefully spray a little cleaner into the pot while working it through its range. You really don't have to be a tech to do this and most post are easily accessible.
     
  7. bgavin

    bgavin

    Joined:
    May 3, 2001
    Location:
    Orangevale, CA 95662
    On the flip side of this, most pots are soldered directly to the board.
    Similar to an input jack that is board-mounted, these can be a royal pain to replace, for the duffer.

    I'm not an amp tech, but would estimate 1.0 to 1.5 hours labor time, plus parts.
    If the board is deeply buried and requires significant disassembly, add more time.
    This should factor into the purchase price.
     
  8. bobcruz

    bobcruz

    Joined:
    Mar 10, 2004
    Location:
    Alameda, CA
    I'd be more worried about not trying the amp before buying it to gauge other possible issues. OP, will you be able to return the amp if it's not fully functional, other than the scratchy pots?
     
  9. webmonster

    webmonster

    Joined:
    May 19, 2013
    Location:
    New Zealand
    What sort of amp and what age?
    Removing the cover and squirting some lube in the pots usually works a treat.
    However, if the time comes when this is no longer effective then the pots might need to be replaced - probably easier with a vintage pre-PCB amp.
    An additional issue would be replacement of unobtainable tapped pots if the amp is vintage.
    so... what sort of amp and what age?
     
  10. Mr. Foxen

    Mr. Foxen

    Joined:
    Jul 24, 2009
    Location:
    Bristol, UK
    Disclosures:
    Amp tinkerer at Ampstack
    Sometimes pots get noisy from having DC across them, either by design (presence controls on old Laneys) or by having a leaking capacitor that should be blocking the DC. Can find that with a meter.
     
  11. jfh2424

    jfh2424

    Joined:
    Jan 10, 2009
    Location:
    Montreal, Quebec Canada
    Hello everyone.

    First of all, thanks for all the responses. I appreciate it!

    The amp I am looking at is a GK 1001RBII. Would this be an amp that is simple to address the scratchy pot issue, even for someone with no experience?

    No, I am not going to be able to try it out before I buy it. I don't know exactly how old it is. I've asked, I guess we will see.

    Thanks!

    john
     
  12. B-string

    B-string Gold Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    IIRC the preamp board is mounted foil side up. Takes a little time to remove it to properly spray the pots. No clipping wires or re-soldering needed, just a lot of nuts on the pots.
     
  13. flatfender

    flatfender Ad eundum quo nemo ante iit Supporting Member

    Joined:
    Sep 27, 2012
    Location:
    Black Hills of South Dakota

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