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1001rb need help or I might trash the amp

Discussion in 'Amps and Cabs [BG]' started by Boatmanb, Mar 20, 2014.

  1. Boatmanb


    Mar 20, 2014
    Hello all, I am new to this forum. I joined because I am in need of some advice on troubleshooting.
    I have a Gallien-Krueger 1001RB mark-2 I am trying to repair. A short in the speakon cable I was using caused a hole to be burnt in the circuit board of the power amp. So I ordered a new power amp from Gallien and installed it. When I turned it on I got some fuzz from the speakers and then a fire in the pre amp. One of the op amps burned up taking a capacitor with it. After failing to fix that circuit myself I ordered a new pre amp board and installed it today. Still not working.

    When I turn the power on the clip light stays on steadily. There is no power light or sound coming from the amp. Any suggestions on what else could be wrong with it after replacing both circuit boards?
  2. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    No offense meant, but it seems you should enlist the aide of a qualified amp tech. I too, am quite skilled with electronics, but always hire a tech to work on my amps, as they have both the skill, and required test equipment to properly diagnose and repair these things.
  3. Jeff Scott

    Jeff Scott Rickenbacker guru.......... Supporting Member

    I thought these amps had short circuit protection that would shut the amp down to prevent a disaster? :meh:
  4. bass4worship

    bass4worship Ready For Freddy, let rock Supporting Member

    May 4, 2009
    Sebring, Florida
    You may have damage the power amp broad again by not checking that the preamp was bad.
  5. Boatmanb


    Mar 20, 2014
    I am a limited energy electrician and have worked with circuit boards quite a bit as a hobby but I have done little with the inner workings of amplifiers so I think you are right RickenBoogie, I'll need to take it to a professional.

    It was the lm3886t op amp that originally blew on the power amp from the short. When it blew it did stop the current but the op amp exploding burned a hole in the board. Not the best short circuit protection if you ask me:rollno:
  6. cableguy


    Jun 4, 2009
    North Bend, WA
    I would send it back to GK and have them work on it. They do non-warranty work. They would be able to tell you if the amp would be worth saving.
  7. Jeff Scott

    Jeff Scott Rickenbacker guru.......... Supporting Member

    If it protected the output transistors from blowing then I'd say the protection worked just fine............... :bag:
  8. agree.....i'm an ampeg or mesa tube guy,but gk has too good a name around here to dismiss without at least allowing them an opportunity to look at it....
  9. Steve Dallman

    Steve Dallman Supporting Member

    You neglected to troubleshoot the power supply when the amp first burned. There are detailed, systematic instructions on how to test an amp like this, requiring an oscilloscope, signal generator, variac, and proper meter, plus dummy load, etc.

    If you don't have the service manual, you need it. If you don't understand it, let the tech have it with your amp.

    At the very least, powering up an amp after a big repair requires using a light bulb limiter, that is a special socket that puts an incandescent light bulb in series with the amp when you plug it in.

    IF there is a short, the bulb will burn brightly but the amp won't be harmed. I suspect a filter cap shorted in your power supply. Possibly a diode in the rectifier, or voltage regulator is bad. Just guesses.

    Sending the amp to GK for repairs will likely be cheaper than having a tech fix it. I have had bad experiences with GK repair, but I believe they upgraded their test and rework procedures since they nearly butchered my 1001RB (warranty work.)
  10. Steve Dallman

    Steve Dallman Supporting Member

    Repairing an amp by just changing out boards willy-nilly is no way to repair an amp. I got the service manual for my GK from GK. The tweeter amp wasn't working in mine and under warranty I sent it back. They couldn't find the problem but they upgraded the turn on transient protection circuit.

    I got permission to repair the tweeter amp (and found the problem right away) without losing the warranty.

    I also had to rework the mess they made with their "upgrades". They burned the preamp board when they changed an op amp and put in a cheap socket. Badly burned. I sent them pictures.

    They replaced a few components without removing the circuit board, attempting to solder them from the top of the circuit board (the pads and traces are under the board.)

    This left solder blobs dripping from the power amp circuit board, hanging enough to nearly short on the chassis. I sent them pictures.

    After receiving the pictures, I got a letter stating they held a seminar for their techs on proper re-work techniques and held a soldering seminar.

    They changed their test procedures for testing the tweeter amp. Their new procedures would have found the problem with my tweeter amp.

    I was NOT impressed with the sloppy work the GK tech did. It was just terrible. AND at no time did GK offer to properly fix my amp. They did offer to replace the amp, but for personal reasons not important here, I passed on that. I had no problems with the amp after I redid their re-work, and repaired the amp.

    This was quite a few years ago now. The series 1 RB amps were still out. I trust GK has solved their tech problems. I would have no qualms about buying another GK...but I'm not crazy about the GK sound. I gigged with my 1001RB for many years.
  11. okcrum

    okcrum in your chest

    Oct 5, 2009
    Verde Valley, AZ
    RIP Dark Horse strings
    Steve's right. You very well may have killed one or both of the new boards you installed if all the smoke is just a symptom. G-K or tech time.