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Fix for Genz-Benz Shuttle 6.0 noise problem

Discussion in 'Amps and Cabs [BG]' started by tucson_zac, Jan 2, 2013.

  1. tucson_zac


    Sep 11, 2007
    Tucson, AZ
    Had my Genz-Benz Shuttle 6.0 die on me at a recent rehearsal. It started making a loud white noise, and the signal that made it through was heavily distorted. Noise existed even with all the controls at zero, and the mute on. Luckily I was on upright, and the drummer just went to rods while I went acoustic.

    With some quick troubleshooting, was able to determine that the signal out of the DI was fine both pre- and post-EQ, which isolated the issue to the power amp section. Noise also came through the headphone jack, which comes straight off the power amp through resistors. Also noted that the signal light would tun on with the noise, which according to the G-B block diagram, would isolate the issue to the master volume gain stage (before the switching power amp).

    At this point, I took the amp over to my Dad's (retired electrical engineer, he loves to fix electronics). We pulled the lid off, and first checked for any obvious issues (broken components, solder joints, leaking caps, burn marks) and saw nothing. Next he poked around the circuit cards with a wood stick, and was able to make the noise come and go by tapping on the forward-most board. He tapped each of the components until we found the culprit, a small connector.

    This is a short grey harness that connects near the master volume knob, and the middle of the same board. Not sure without a schematic, but we are pretty sure this is the feedback line for the master volume gain stage. A little contact cleaner and reseating both ends of the cable, and the amp is working perfect.

    Don't really know the history of this amp, I bought it used at a pawn shop a few months ago (I already had another Shuttle 6.0, but couldn't pass up the deal on the second). So it might have already had the issue before. Luckily wasn't at a gig :)

    Anyway, hope this helps if anyone else ever has this issue.

    Jim Carr likes this.
  2. Seen this a few times here. Always good to add the solution to the search engine! :)
  3. alanwest60


    Oct 8, 2015

    I had the same problem and found your post. Followed the fix instructions and the amp is back to it's former glory. Crazy that such a simple problem can cause so much noise! Many thanks.
    /\/\3phist0, s0707 and Jeff Genzler like this.
  4. Grooveline

    Grooveline Supporting Member

    Jan 24, 2012
    Wow, literally going through this same problem right now at this moment. I hop on here find your post and now my mind has officially been blown by the knowledge and helpfullness of talkbass members yet again. Seriously THANK YOU!
  5. Red Planet

    Red Planet

    May 29, 2005
    Talking Rock GA
    OEM Manufacturing Supplier
    Wow this must be multivu. I had the same problem recently and used the same fix. The noise was coming from the connector assembly that holds the tube in. I removed it srayed both ends with Deoxit and the noise went away. I first swapped tubes and that did not get it.

    BTW mine is a Shuttle 9.0.
    Last edited: Oct 9, 2015
  6. BoogieZK


    Sep 28, 2008
    Toulouse, France
    Can you make a good photo shot of the connector,plz? i have the same issue!
  7. Lincoln


    Nov 3, 2006
    Yes a photo would be great before I go kicking this bad boy around on it insides!
  8. Grooveline

    Grooveline Supporting Member

    Jan 24, 2012
    Lincoln, I don't have a picture but from what i recall it was as easy as making sure the wire harness was seated properly. The harness talked about will be the only one right behind the master volume knob. I'm pretty novice at electronics but was able to find it pretty easily and give it a firm push to make sure it was seated correctly. Haven't had a problem since.
  9. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    These ribbon connectors seem to become a problem no matter who makes the amp. I’ve had problems with two Carvin units. Cleaning and reseating the connectors solved both problems.
  10. Grooveline

    Grooveline Supporting Member

    Jan 24, 2012
    If you try to search on this issue many other threads/people have linked the issue to the tube or how it was seated. I originally thought this was my problem as well because after I took the top off and resat the tube the sound went away. It wasn't until it came back on me that I did more research and found this thread. Thankfully the OP and his dad's knowledge have been able to help a couple people out. If this doesn't solve the problem however I think you could ask member AgedHorse and he might be able to help out.
  11. /\/\3phist0

    /\/\3phist0 Mesa Engineering! Warwick-G&L-Source Audio Supporting Member

    May 7, 2007
    noahw1 likes this.
  12. aigman


    Jun 5, 2004
    Funny thing finding this thread, my Ashdown did the exact same thing. Today.

    I’ll bust the DeOxit out.... best places to spray under the hood? Spray indiscriminately?
  13. Absolutely NOT. You can cause more trouble and invite a major failure.

    Interconnect cables, tube sockets and jacks (especially jacks with switching contacts) and inside the wiper portion on pots (NOT down the shaft) and sparingly. A little goes a long way. A lot damages.
  14. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    There have been a few problems with the tube and tube socket, mostly caused by a bent tube pin damaging a socket contact. I just fixed a Shuttle today with a badly bent tube retainer that allowed things to bounce around pretty good.

    There have also been a few amps with the jumper behind the master volume control with the pin sockets not fully seated causing noise. Removing and reinstalling generally takes care of it for good. Otherwise, I haven't seen any connector or header issues in the last couple of years.
    /\/\3phist0 likes this.
  15. Grooveline

    Grooveline Supporting Member

    Jan 24, 2012
    Ok, fired up the shuttle 9.0 after a couple months (using mostly the v4b at the moment) and it seems the noise is back. Got the amp open now but i'm not able to disconnect any of the clips holding the wires to the board. Can't get them to unclip and i dont want to rip them off with needle nose pliers. Any help here?
  16. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Just give it a gentle tug then push down on the white plastic header shells. No need to remove the jumper, you are just re-setting the contact shell to tye contact sockets.

    If this doesn't work, PM me and I will help you with more troubleshooting.
    noahw1 likes this.
  17. aigman


    Jun 5, 2004
    Thank you for the reply sir, the search function was making my head spin!
    B-string likes this.
  18. If it winds up needing to visit a shop the info will save them a lot of aspirin and time repairing the damage..
  19. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    If needed, I still handle all factory level repairs for GB
  20. aigman has an Ashdown with a similar issue not a GB.