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Peavey Triumph PI hum/noise

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  • #16
    I meant the power tube screen resistors. You can check them without removing anything. The standby switch in that amp lifts screen voltage and one side of the switch connects to the screen resistors. So, you can measure from the standby switch to pin 4 of each tube socket to check each screen resistor.
    Last edited by The Dude; 07-03-2019, 02:11 AM.
    "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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    • #17
      Originally posted by The Dude View Post
      I meant the power tube screen resistors. You can check them without removing anything. The standby switch in that amp lifts screen voltage and one side of the switch connects to the screen resistors. So, you can measure from the standby switch to pin 4 of each tube socket to check each screen resistor.
      Got it, will do!

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      • #18
        Also you can just measure the DC at pin4 to see if the screen resistors are good.
        While you're at it, might as well check all grid, cathode, and plate DC voltages for power tubes and PI.
        (unless you have already done it and all were in ballpark of schematic values)
        Originally posted by Enzo
        I have a sign in my shop that says, "Never think up reasons not to check something."


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        • #19
          OK, issue has been resolved, but in the least satisfying way possible, because I'm not even sure what solved it. I know that I screwed up at least one thing, maybe two. Was hunting on stuff today and realized that the noise was on V4 as well (which I wrongly thought was just for the reverb) and eventually found that I had one of the Molex connectors off by one pin, so the effects loop wire was an antenna. I know however that this wasn't that way before since I had gotten output when lining into the effects return before, and had unplugged that connector in replacing C57. So correcting that issue and adjusting the hum balance got rid of the hum and noise.

          Thanks for the input, if you guys hadn't replied this thing may be sitting at the bottom of a lake or something. Time to hand it off to the guy who wants to buy it from me and hope it never comes back.

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