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GK 800RB Troubleshooting....HELP!!!

Discussion in 'Amps and Cabs [BG]' started by sterlingballboy, Dec 27, 2004.


  1. sterlingballboy

    sterlingballboy

    Aug 17, 2004
    My 800RB just stopped working and I need some advice on troubleshooting it. It powers up (fuse is good). It is working intermittently and then stops producing sound. I had it running through sn SWR 4x10" (8 ohm cab) through the 4 ohm output (which I know is a bad idea), but it worked like that for months. It has taken a couple of hits in it's rack case so it might have jarred something out of place. Before cracking this baby open, I was wondering if anyone had any sound advice for me ahead of time. Any help would be appreciated.

    JM
     
  2. adam on bass

    adam on bass Supporting Member

    Feb 4, 2002
    New Braunfels, Texas
    Endorsing Artist: Spector, GK, EMG and D'Addario
    8 ohm cab with a 4 ohm output? That 4 ohm output should be an input run in parallel with the other input so that shouldn't really be the problem. I would say there is a resistor loose in the head, I have heard of it before. Those are great heads.
     
  3. eots

    eots

    Dec 18, 2004
    Morris, IL.
    As a method of troubleshooting, when this happens, plug your bass into the effects return jack( bass vol.down) then play a note bringing up the vol. on the bass. ANY Sound? if so, the problem's in the preamp section. IF none still, then likely in the power amp section. Upon opening up my amp, all I could come up with was that the preamp bd.(the one all the knobs and the input jack are attached to) may have had a trace come in contact with the face plate, thereby grounding the input. I put a strip of electric tape between the bd. and the face plate to separate the 2 and all seemed okay. Does this problem come and go?
    An 8 ohm cab is fine, you just don't get all 300watts working for you that's all. Working on your amp is easy cause everything is laid out well and is nice and tidy. There is a top and bottom cover that can come off for inspection. You might see if that jarring that occurred perhaps reduced what small gap there already was between the preamp bd. and the face plate. To duplicate the remedy I used ,you'll have to remove the knobs and associated nuts and screws holding it all together. Make note of where the bd. lines up and stick the tape across the length of the face plate. Don't cover up any holes where pots and led's need to protrude and reassemble. While you're in there, make a general inspection of components. Look for hotspots or suspicious connections. If you have a soldering iron and feel competent enough, reheat some solder joints.
    Hope this helps.