Fender Hot Rod Deluxe Bass tone control doesn’t work

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by bassman_al, Jun 24, 2019.

  1. bassman_al

    bassman_al Member

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    Hi all! Just got a cheap HRD MIM and it works fine, all tubes glow, no crazy noise problems, reverb and channels function fine but it was in storage a while and the bass tone knob isn’t working. So the amp sounds very thin. Any ideas of what the problem is? I own a guitar repair business and have some limited experience working on amps, so if there is a way I can save a trip to my amp tech, I’m all ears. Thanks!
     
  2. Tron Pesto

    Tron Pesto Member

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    That kind of thing is almost always* a bad/broken solder connection from the pot to the PCB. (Rarer, but possible, is a crapped out pot.) If you have the wherewithal, inspect those joints and reflow solder.

    *Having said that, I risk jinxing you - opening up the possibility for a more complicated problem. I will keep my fingers crossed for you. (Damn, that might be a double-jinx...)
     
    Kyle B, bassman_al and mabinogeon like this.
  3. pdf64

    pdf64 Member

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    I read reports that the mini pots Fenders use can somehow short out, but they respond well to a good clean out. So try a good quality lubricating cleaner spray and twist the knob over its full range a few times.
     
    Kyle B, Tron Pesto and bassman_al like this.
  4. Kyle B

    Kyle B Supporting Member

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    100% agree this is the most likely scenario.

    OP --- To test for this, I might suggest a simple experiment. If you remove the knob, then unscrew the small nut, the potentiometer can be 'wiggled' a bit. (By design the pots are hard-fixed to the chassis via that nut... with no nut the pot is only being held in place by the PCB). Try that when the amp is running, see if wiggling it causes an intermittent connection (i.e. the pot starts working when you push it to the left or some such...) Failure to observe this effect doesn't rule out 'bad PCB connections', but observing it almost guarantees that IS the problem. Won't take more than about 5 minutes to do...
     
  5. bassman_al

    bassman_al Member

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    Great idea!!!
     
  6. xtian

    xtian Member

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    Another simple test: put guitar directly into "Power amp" or FX return jack, and make sure the sound is full bandwidth. This way, you're completely bypassing the tone stack.
     
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