GK pink ring of doom

Discussion in 'Amps and Cabs [BG]' started by Brainmisspelled, Jan 23, 2022.

  1. So I started to get the pink ring of doom on my GK mb115 (where the ring around the power button goes from red to pink rather than red to blue upon power up) after lots of reading I found out this means the power amp is fried so I ordered a new 50ASX2BTL power amp. It didn’t seem like replacing it would be very difficult as it’s just 4 screws and 6 plugs to disconnect and reconnect.

    I’ve now installed the new power amp and there is no light at all around the power switch! Figuring I probably put it in wrong so I tried installing the old one to see if I could atleast get the pink ring of doom back…i figured if I put the old one back in and get it back to what was happening before than I must be installing it right….sure enough when I put the old power amp board back in and power it up it works like it used to (red to pink) so it seems like I’m assembling it right.

    i put the new one back in AGAIN and again nothing. No lights no sounds no action.

    does anybody have any ideas on what I should do now? Did I miss a step somewhere or something? Possibly the wrong part? (I don’t think so because I asked Gk what to get) maybe I just got a bad replacement power amp? I donno I’m lost at the moment so any help other than call Gk would be appreciated. Thanks
  2. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    A couple of possibilities, the first being that there is another fault in the amp and new the replacement part is damaged.

    The other possibility is that you bought a counterfeit power amp module. If it came from China or Hong Kong, it’s almost certainly counterfeit (even if it looks legit).

    This is why troubleshooting is important, identifying the actual fault, and verifying that there is no additional damage.
    Afc70, SirMjac28, mb94952 and 9 others like this.
  3. I think I actually found the problem…I ordered it from parts-express.com…GK recommended them so I don’t think it’s a counterfeit.

    …it’s certainly not well produced though because it’s missing 3 resistors…I’m thinking I was just sent a bad part. What do you think?

    side by side B3E76157-DCEA-48C6-AE9E-E2C7712F6FAA.jpeg

    old one D8147D1E-F509-4600-999B-CF9D16C11254.jpeg
    New one 5F5366D1-2FED-4D4A-8EB6-C6DB03325655.jpeg
    mb94952 likes this.
  4. Oh and picture from their site:
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    I don't think those parts have anything to do with your problem. There are different evolutionary versions of this module.

    Either the module is defective or there is more wrong with your amp that's causing the issue with this module and the new module is now damaged.
  6. I think missing 3 resistors constitutes defective…and would explain the results I’m seeing.

    The new one when installed shows now sign of power at all…like the circuit is broken somewhere…like those three places there would usually just be a little electrical resistance.

    the pre amp and speaker work so the problem is definitely in the power amp board…I’m putting the boards in correctly because I can put the old one in and it atleast gets back to where it was, so the problem is in the new board…which is missing components. I’ve poured over them both…everything seems to be the same except it’s missing 3 resistors…so I don’t think it’s a different build of the power amp board because it looks identical. I think I just got one that had an error in manufacturing.

    why don’t you think it’s this?
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    No, it doesn't explain what you are seeing, you just don't know what you are looking at and are unwilling to listen to somebody who has 20 years or working directly with IcePower and their products. The most recent revision does not have these resistors installed, I looked at my docs and they are not supposed to be there. They are part of a high voltage bleeder or snubber that's not needed. I have one here without those resistors and it works perfectly fine.

    You are new here, you asked for help, you got more than qualified help, and now you are arguing with me? C'mon, maybe you don't know as much as you think you do, that's fine, but don't argue with someone who understand more than you do about this.

    Now, the most common causes for a new module not operating is either a missing BTL programming jumper (some versions have this and some don't, because some boards were configurable for dual single ended or BTL) and the other common cause is a failure of the installer to understand that the power supply needs to be jumper configured for 115/230V. Fortunately for you, you didn't realize this and your module is factory configured for 230V and must be changed to 115V in order to work properly in the US. This, of course, has nothing to do with the missing resistors.

    Change the jumper (disconnect from the power source first).

    Another common cause of damage to these modules is rough handling which physically damages components on the bottom of the PCB. I see a few modules a year returned by techs claiming defective when in fact they damaged the modules themselves.
  8. It was the jumper thanks!
  9. Foz


    Jul 26, 2008
    Jax FL USA
    Funniest thread on TB!
  10. wintremute

    wintremute mediocrity at its finest

    Oct 16, 2014
    Endorsing Artist: Langstrom Carrot Farms
    AgedHorse, again showing himelf to quite possibly be TBMVP.
  11. foolforthecity

    foolforthecity Supporting Member

    Brain, I suggest you now kneel before the Master. When he speaks, we listen
  12. Ekulati

    Ekulati Supporting Member

    Jan 2, 2016
    Richmond, VA
    Someone with graphic skills, we need one of those Batman smacking Robin memes customized to the Horse...
  13. castlev


    Mar 28, 2010
    New Jersey
    I'm glad I can at least contribute something useful.

    Attached Files:

  14. 4dog


    Aug 18, 2012
    and there was much rejoicing!
  15. dougjwray


    Jul 20, 2005
    Wow, that was awesome!
  16. roborend

    roborend Supporting Member

    Jun 10, 2012
    Rock Island Illinois
    Epic solvage
  17. Incase anyone was wondering why I normally say idk when someone asks me for advice on a problem
    wintremute, Brich and marko138 like this.
  18. EE734C5C-324C-4C60-A119-D8A2B4A16864.jpeg
  19. Hah. Love it.
    mb94952 likes this.
  20. 31HZ

    31HZ Glad to be here Gold Supporting Member Supporting Member

    Feb 26, 2006
    Central VA, USA
    "Thanks, @agedhorse -- I appreciate your help, you really saved me there! Sorry I got defensive for a minute, my apologies."

    There you go, OP. :thumbsup:
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

    May 21, 2022

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