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Help diagnosing problem with my Mpulse 600

Discussion in 'Amps and Cabs [BG]' started by Taylor Livingston, Sep 27, 2008.


  1. Taylor Livingston

    Taylor Livingston Supporting Member Commercial User

    Dec 25, 2002
    Oregon, US
    Owner, Iron Ether Electronics
    I am having some serious issues with my MPulse - I turn it on, there is almost no bass sound coming through (I can hear a faint sound coming out when I play), but mostly just static. The speaker will extend outward, wait a second or two, then go back in. Then I get a very loud pop.

    I was trying to figure out what section of the amp was malfunctioning, but the effects loop was already not working, so I can't bypass the preamp. Just now I turned it on, with nothing in the input, and not connected to a speaker. There is an intermittent click (about every 5 seconds or so. Upon the first click, the compressor light comes on very brightly, as if there is a very loud signal going into it that it has to compress heavily, then upon the next click, the light goes off. This repeats.

    Any thoughts on what is happening? I just moved to Baltimore and don't know where to take stuff like this, and if it just sounds like it needs a new preamp tube, I can do that myself.
     
  2. I had a similar problem, but I am not 100% sure here as my effects loop funtioned just fine. I tested it by running a cable from the effects output into my practice amp. It had sound out the effects both my gain and master volume. I had the pop and heavy static problem on the speaker output, before it completely died.

    On my WalkAbout it ended up being a bad resistor on the output tube that drives the FETs. The part and labor was covered under the 5 year warranty. Contact Mesa's US Domestic Support: (707) 778-6565. When I called I had to leave a message, but they got back to me within 48 hrs, but only had 3 locations in S. FL one being about 100 miles away.

    Edit: You will need a copy of your receipt, even if you filled out the warranty card. The repair shop needs it to submit the warrenty claim or else you'll have to pay for diagnostic, parts, and repair out of pocket. Atleast that what I was told by Mesa, GC when I picked up a reprint of my receipt, and the repair facility in the local Sam Ash.
     
  3. Taylor Livingston

    Taylor Livingston Supporting Member Commercial User

    Dec 25, 2002
    Oregon, US
    Owner, Iron Ether Electronics
    Well, I bought it used, so no receipt, and likely no warranty. I guess it is not something I can fix, so I will have to take it in to be repaired. Thanks for the help.
     

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