Monoprice 15 watt goes dead after a year.

Discussion in 'Amp Tech Center' started by Keefsdad, Oct 8, 2019.

  1. Keefsdad

    Keefsdad Tele-Holic

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    I've been averaging 3-6 gigs a month with it, put new JJ power tubes in it when I got it. It just went dead in rehearsal today. I'll have access to it tomorrow so I'll open it up and take a look. Hoping it's just the power tubes. Any advice would be welcome.
     
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  2. Rick330man

    Rick330man Tele-Afflicted

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    The simple things first.

    (1) Is the pilot light turning on? (2) Do you see each tube lighting up when you turn it on? (3) Is it completely dead showing no signs of life?
     
  3. Keefsdad

    Keefsdad Tele-Holic

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    Yes, no pilot, no signs of life.
     
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  4. archetype

    archetype Fiend of Leo's Silver Supporter

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    IIRC a Monoprice 15 has multiple fuses and/or fusable links inside. Break out the schematic to identify them and go fuse hunting.
     
  5. The Angry Possum

    The Angry Possum Tele-Meister

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    I have one also, I'll keep an eye on this thread.
     
  6. Tonetele

    Tonetele Poster Extraordinaire

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    No piiot light means the fuse may have shut everything off. Try a new fuse,which is probably not the answer, it;s likely to be in the input transformer or part of the circuit. JMHO. So multimeter out.
    Unlikely to be the valves/tubes unless they blew out They'll be blackened ) with the fuse meaning too much current somewhere.
    P.S You'll need to replace the fuse whatever the problem.
     
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  7. MrClint

    MrClint Tele-Meister

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    Watching this thread closely as well. For the sake of greater understanding, are you plugging in to a surge protector? I know there is some debate about their use, just curious.
     
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  8. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    I'm not sure how a surge protector would be related?

    These amps are cheap, and there have been several threads lately about them blowing up in interesting ways. If you do your own tech stuff, you might be able to make it live. If not, it may not be worth taking to a tech, especially if you have already tried fuse/tubes.
     
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  9. Whatizitman

    Whatizitman Friend of Leo's

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    Not sure if OP has had a chance to open it up, yet. But checking the fuse would be the immediate first thing to check once its open. My bet is power transformer. These amps are not old enough to start having weird circuit/component breaks/leaks, etc....

    This is the problem with cheap amps. Anything can break down prematurely. But these are so cheap they are rarely worth taking to a tech for repair if you can't get it fixed under warranty.

    I like to find broken stuff to fix, so no biggie for folks like me. But even so. A guy four hours away from me has a broken VHT ultra I'd like to get my hands on to fix and/or do some robrob mods. Not sure an eight hour round trip is worth it for an amp I couldn't turn around to sell or trade for anything once it's fixed. It is what it is.
     
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  10. L.A. Mike

    L.A. Mike Tele-Afflicted

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    My amp tech tells me the boards on these types of Chinese amps are so cheaply built that they are almost impossible to repair.
    If it's just a tube or transformer, it might be worth fixing.
    The tech I use has a $50 diagnostic fee that is applied to the repair bill if I want to proceed. Add in some more labor and parts and then decide what to do.
    I believe these have a one year warranty. You ship it back to them at your expense and they ship you another one.
     
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  11. schmee

    schmee Poster Extraordinaire

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    The fuse is internal inside near the transformer. I put a normal fuse holder accessible from the outside in mine. I am in process of converting mine to a BF Princeton. I'm about 80% done.
    I have boards available and the PT also
     
  12. Keefsdad

    Keefsdad Tele-Holic

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    Can't find the fuse.
     
  13. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    can you post a picture of the board?
     
  14. Keefsdad

    Keefsdad Tele-Holic

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  15. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    I mean, in theory it should be connected to where the power cord goes, which I can't really tell from that picture.
     
  16. schmee

    schmee Poster Extraordinaire

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    Yours appears different than mine. Mines an early mono 15. Follow the AC wires/switch wires, gotta be there somewhere!
     
  17. Keefsdad

    Keefsdad Tele-Holic

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    Found it, there is a little cover over it from some reason. Ordered the fuses online.
     
  18. MrClint

    MrClint Tele-Meister

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    A power surge/lightning strike or fluctuating power draw wouldn't potentially blow a fuse in an amp? I unplug all my gear when not in use as well. I must be making some overly cautious/wrong headed assumptions. How about trying a $6 3-wire receptacle tester when you plug in to a new location? I should just plug and play without any concerns regarding the power source? If I'm just being superstitious, it isn't costing me very much.
    [​IMG]
     
  19. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    3 wire tester is definitely a must have. Music stores leave stuff plugged in eternally, and studios, and most home users. Haven't heard of a problem yet.
     
  20. MrClint

    MrClint Tele-Meister

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    Just giving this thread a bump. Hoping for an update.
     
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