Vox Pathfinder hums but no guitar audio

Discussion in 'Amp Tech Center' started by foundjoe, May 13, 2015.

  1. foundjoe

    foundjoe Tele-Holic

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    I inadvertently shorted out something in my Pathfinder by plugging in a speaker extension cable where the separate speaker leads on the other end touched. Now the amp just hums and won't produce any guitar audio on output. It does the same when I plug headphones in. Also, when I turn the power switch off, the indicator light stays on a few seconds before dimming and shutting off. Any idea what might have got shorted out? I'm not sure if I can fix it myself, and I'm hoping it doesn't cost a lot to repair (especially compared to the low price of the amp).
     
  2. Cleeve

    Cleeve Tele-Holic

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    You popped the power op amp.
    TDA2030 or TDA2040, either will do.
    LM1875 will also work and may be easier to find. Any of those sound exactly the same.
    The board is single sided, so it's pretty easy to de-solder the old one, it uses a 5 pin to-220 case.

    There are a couple of resistors in the power supply that could suffer, but I did the exact same thing with mine and only the tda2030 was smoked, the worst part is pulling the knobs off and getting the board out.

    That op amp is common in consumer audio and televisions, at least it was- you may find it easier to have it fixed by a radio / tv / car stereo place, as long as you let them know it's solid state with no surface mount stuff, and it's not digital.

    If you can't find a place to fix it, it really is something you could do yourself with the cheapest of soldering irons and no risk of getting shocked (assuming the amp is unplugged from the wall!).
     
  3. foundjoe

    foundjoe Tele-Holic

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    Thanks for the information. I haven't taken it apart yet, but I've seen a pathfinder schematic and found the TDA2030 location. I'll try to report back if I get this up and running again.
     
  4. foundjoe

    foundjoe Tele-Holic

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    I ordered a 3-pack of TDA2030s, and after installing a new one, still had the same problem. I swapped out it one more time, but still no luck. If there are any other ideas, I would be glad to check it out, but I may have to take this to repair shop. Thanks!
     
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