Little Mark Tube 800 Transformer Issue

Discussion in 'Amps and Cabs [BG]' started by PhunkMusic, Jun 4, 2021.

  1. PhunkMusic


    Jun 4, 2021
    I've had this amp for awhile now and it has worked great. I was loading into a gig once and dropped the head. It worked fine but I had to give it a little smack for it to turn on. Today I finally opened it up to see what might be the issue. I pushed on the output transformer (at least I think that's what it is) and the amp turned on. However, now that i've done this, the smack no longer works and when I push the transformer it only turns on as long as I'm holding it down. Now maybe touching this transformer while the amp was on was a stupid idea but here I am. Any suggestions? Is the thing just loose or do I have to take it in and get a new one installed?

    Here is a video of it:

  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
    Something is broken on the PCB from the fall. Could be any of the surrounding parts, possibly but not likely the power transformer.

    Because this is in the area of the non-isolated primary supply, it is a safety issue when probing or touching these parts. It can be dangerous (even fatal) if you contact the wrong points.

    You need to find a qualified service tech that works on SMPS type amps. I do not believe MarkBass supports the supply parts, only complete replacement assemblies, which makes sense due to the safety certification of the supply.
    rickdog likes this.