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Mesa Boogie WalkAbout thermal event

Discussion in 'Amps and Cabs [BG]' started by Rad01516, Sep 21, 2008.


  1. Rad01516

    Rad01516

    Feb 8, 2008
    I played a fairly low volume outdoor gig today and my WalkAbout shut down early in the first set. Gain was about 11/12 and master was set at about 12. I plugged into the piano players amp and finished the set. I tried again during the second set and the amp lasted about half way through before shutting down. Outside ambient temperature was about 79 degrees F and the amp was pretty much in direct sunlight. Never had an issue before and was wondering if others have had similar experiences
     
  2. fenderhutz

    fenderhutz Supporting Member

    Jan 28, 2007
    Harpers Ferry WV
    2ohm or 4ohm operation?
     
  3. Rad01516

    Rad01516

    Feb 8, 2008
    4 oms using Scout cab. I have been running the amp for a few hours now to see if I can recreate the event. Amp is running fine and cool.
     
  4. fenderhutz

    fenderhutz Supporting Member

    Jan 28, 2007
    Harpers Ferry WV
    Generator power source?

    Everyone hooked up to one outlet?
     
  5. Rad01516

    Rad01516

    Feb 8, 2008
    PA, Piano amp and WalkAbout on same power strip w/extension cords. House power.
     
  6. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Direct sunlight can surprise you. I once played an outdoor gig, and the heat sink on top of my GK MB150 combo got hot enough to fry an egg. Fortunately I was using an extension speaker, so I put the entire amp underneath the trailer we were playing on.

    The other thing is, are you sure it was thermal, and not low AC voltage? Maybe something else on the same circuit (refrigerator, etc.) brought down the voltage temporarily, long enough to trip the amp.
     
  7. Rad01516

    Rad01516

    Feb 8, 2008
    It was definately hot today and the black scout cab absorbed a lot of solar load. I assumed it was a thermal shut down as the amp was pretty hot to the touch (it also phased in and out prior to shutting down) but the line voltage is suspect as well. I plan on running a load on the amp to see if the issue surfaces again prior to using it on a gig.
     
  8. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    I've not had that issue with mine, not even outdoors in direct sunlight, running at 2.67 ohms.
    I'd advise cracking it open, and making sure that the fan is working, and that it's got clean access to fresh air: no clogs, cathair, etc.
     
  9. pfschim

    pfschim Just a Skeleton with a Jazz bass Supporting Member

    Apr 26, 2006
    SF Bay Area
    similar to chef, but even a bit more extreme. 4 hours, 108 degrees(but in the shade though), 2ohm operation (4ohm WA12 on top of a 4ohm Scout 15), master at 12noon. No problems at all.

    Could be the quality of the power. I will second Chefs suggestion to check it out yourself, and if you do not see anything obvious, perhaps have it checked by Mesa or an authorized shop.

    good luck
     
  10. Rad01516

    Rad01516

    Feb 8, 2008
    Update. I checked with the Mesa folks who directed me to High Tech Electronic Service, Lawrence MA. After a bit of discussion they had me check the effects send. They said that there is a known problem with the effects loop ΒΌ inch input jacks. The jacks can become corroded (especially if not used) and when the toggle is in the F/X On position, the amp can cut out. Vibration can trigger this as well. They walked me through in recreating the amp shut down issue just to be sure I had a faulty jack. Leaving the F/X toggle in the bypass position will solve it. Having the jacks swapped out is a good idea. I thought the worst whilst baking in the sun with a dead amp and plugged into the piano rig. Hopefully this is all there is to it but in the meantime, I think I will have a back up amp with me at the next couple of gigs. Thanks for the comments.
     
  11. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    Yep, that's a known problem.
    You can just bridge the in and out with a cable too.
     

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