Help me trouble shoot my GK amp please! With video samples

Discussion in 'Amps and Cabs [BG]' started by flojob, Jun 14, 2020.

  1. flojob

    flojob Gold Supporting Member

    Oct 15, 2011
    Hi yall
    Bought this 2nd hand. Has been working fine, but suddenly having problems with the input.
    So far I've tried contact cleaner, but no difference.
    I know it's somewhere around the input, because I go through the return, and sounds fine.
    Anyone ever dealt with this?
    I don't have any electronics experience.
    Here's some clips!

  2. filmtex


    May 29, 2011
    Try a jumper for the Effects Loop, then use the regular input. GK's are known for this.
    flojob and Lobster11 like this.
  3. Dan Arciniega

    Dan Arciniega

    Jan 10, 2020
    sounds like you have dirty pots,
    try turning the knobs one at a time as you play, see if the noise changes.
    best to clean all the pots anyway
    flojob likes this.
  4. flojob

    flojob Gold Supporting Member

    Oct 15, 2011
    I will, and thanks. Is this a fix that lasts, or does it indicate a problem that will only get worse?

    I don't think it's the pots. I don't get any popping when I turn them
  5. filmtex


    May 29, 2011
    I jumped mine ten years ago or so and never looked back. Just grab a short pedalboard cable with right angle connectors, jumper the effects loop and if it works,forget about it.
    Standalone and flojob like this.
  6. BassmanPaul

    BassmanPaul Inactive

    [QUOTE="Dan Arciniega, post: 24107783, member: 352540"
    best to clean all the pots anyway[/QUOTE]

    Best to leave the pots alone. Way too many amps have been ruined by the indiscriminate application of contact cleaner! :rollno:
    Kro, edencab, Aqualung60 and 4 others like this.
  7. It indicates that the Return jack is in need of a cleaning.
    Here is a copy of another post I did explaining how this works. With pictures. :wideyed:

    For those that do not know this is what the effects return jack looks like. See the nipple between the bottom posts, this is what connects your signal with nothing plugged in. See the signal flow lines.


    When a plug goes in the nipple is lifted, breaking that connection and the signal comes from the cable.


    When you read on here that an amp is cutting out or the volume is good then suddenly goes and we give advice to check the effects loop to see if it still does it, this is why. If it clears up when inserting a plug then that little nipple had some oxidization on it interrupting the signal. It only takes a small film to interfere so you clean it with a wipe of Deoxit D5 and it's all good. No need to keep in the jumper cables.

    Never just spray in the jack as you will get parts that you do not want sprayed and that little nipple is hidden under that post.

    A little rant while on jack cleaning, NEVER file or sand to clean the contact points. The coating on them is thin and has a corrosive protected coating on it and when you scratch that off it will rust fast, making your problems come back faster and eventually killing the jack. Also your filings that come off could go somewhere you do not want.
    A lite chemical wipe is all you need to clean and protect.
  8. flojob

    flojob Gold Supporting Member

    Oct 15, 2011
    Thanks for that, I'll try some contact cleaner on a plug and see if that works off some of the funk.
  9. Look where the nipple is on @S-Bigbottom post. Putting clean on a plug is not going to clean the nipple. But just exercising it might.

    Many times jacks and pots can just be cleaned by exercising them.
    Plug, Unplug, Plug, Unplug, ...

    BTW I don't know what GK it is, but if it has a tube, try re-seating it.
    wave rider and flojob like this.
  10. --Vissinger --

    --Vissinger --

    Jan 31, 2010
    The guys on the music-electronics forum love chasing weird amplifier issues and are pretty good helping people who don't really know how to troubleshoot things.
    flojob likes this.
  11. The nipple is a below where the plug will reach and may require some rubbing to get it cleaned, a bit more than just the plug in and out thing.

    Try both ends of the cable in the loop first Effect Send and Return, if that clears it up go for the cleaning, if not it is tech time contact GK.
    Al Kraft likes this.
  12. flojob

    flojob Gold Supporting Member

    Oct 15, 2011
    Hey turns out that worked, so thank you. You saying I'll need to open it up to be able to clean it?
    Al Kraft and Spidey2112 like this.
  13. arbiterusa


    Sep 24, 2015
    You may not need to. Turn the amp off, then just slide a jack in and out of both the send and return jack a few times. That will probably do it.

    Also, in the future, try to wrap your cable around the cabinet handle or run it underneath the amp from behind so that the the full weight of the cable isn't just being held up by the jack. You will forestall a lot of future problems this way.
    flojob likes this.
  14. cableguy


    Jun 4, 2009
    North Bend, WA
    Glad you got it solved. GK MBFusion into what looks like a fearless 112. Great combo!:bassist:
    flojob likes this.
  15. Kukulkan61

    Kukulkan61 Inactive

    Feb 8, 2011
    Northern Arizona
    I’ve been using GKs for decades and never had this problem or any as a matter of fact...
    flojob likes this.
  16. flojob

    flojob Gold Supporting Member

    Oct 15, 2011
    Yeah I dig it so far, just looking forward to using it in different situations... Like with other folks haha
    cableguy likes this.
  17. flojob

    flojob Gold Supporting Member

    Oct 15, 2011
    Good advice, thanks for that
  18. cableguy


    Jun 4, 2009
    North Bend, WA
    My biggest problem (if you could call it that) with my MBFusion 800 into my 12/6, is very low volume jams where I have my master barely cracked open. Less than 1. These little amps are powerhouses. I think I need a MB200 for my low volume stuff...…...:)
    flojob likes this.
  19. flojob

    flojob Gold Supporting Member

    Oct 15, 2011
    Yeah that's true. I have my gain halfway up, and I can't put the master volume past 2 before it's just uncomfortable. I could easily blow a speaker
    cableguy likes this.