I shouldn't have breathed..One channel is AWOL!!

Discussion in 'DIY' started by WhiteSE, Jun 18, 2017.

  1. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    My Pilot 246 INtegrated now is only operating on one channel.

    I did not touch a thing....

    The two 12AX7's do not light up....I swapped tubes and confirmed the tubes are good...

    Any ideas what would make those 12AX7's take a vacation?
     
  2. bberkom

    bberkom AK Subscriber Subscriber

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    Has the amp been refurbished at all? If they aren't lighting up it could be a power supply issue for the heaters on those tubes.

    Which tube positions specifically are you talking about? Lots of 12ax7's in that amp it seems.
     
  3. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    there are 2 for phono, they light up fine, then there are one on each side of the amp, and then 2 others side by side up front.

    the ones that do not light up are the preamp section for that channel, and then one that sits behind it by itself closer to the output tubes and PS caps.

    I will post pics later
     
  4. trinhsman

    trinhsman Well-Known Member

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    Any fuses in the amp???
     
  5. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    Just the main one...that I can see.
     
  6. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    At the bottom the picture there are the two 12AX7's..one at front and one behind, it sits between a multisection cap and a transformer.
     

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  7. gadget73

    gadget73 junk junkie Subscriber

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    Got a schematic? Possible these run off the output tubes, but not sure.

    Usually if its not lighting its something to do with the heater circuit. If the tubes themselves are known to be good, check the wires at pins 4, 5 and 9 on the tubes that don't light, as well as where the wires on those sockets come from. It may have cracked loose upstream of one of those tubes. If they're run in 6v mode, 4 and 5 are connected together, and the other lead goes to pin 9.
     
  8. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    Moron in action!!! <--------------- The 7025 for phono on far left side was not seated properly!!! Now it all works!!
     
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  9. slimecity

    slimecity Super Member

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    Don't feel bad. I set up a post thinking I had blown up my Accuphase C200 preamp - it sounded all distorted.

    Next minute, turns out it was the power supply crapping out in my cheepie Chinese DAC.

    It happens!
     
  10. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    I replaced some caps..the black STK are the newer ones.
     

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  11. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    Mundorf Mcaps are in....
    Only issue is some hum from the cap I am pointing at...changes as I touch it or get close.
     

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  12. gadget73

    gadget73 junk junkie Subscriber

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    try reversing it. If the outer shield is to the higher impedance side, it will be more prone to humming.
     
  13. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    I will do so...thanks for the tip!!!
     
  14. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    Still humming....gets quieter a tad when my finger gets close.
     
  15. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    When I turn the balance knob towards the center, it quiets down a bit...If I leave it only for that humming channel, its louder.
    If I turn the balance knob all the way to the other speaker, the volume is quite lower that the other side at that volume setting, but no hum comes through the silent speaker or the other nonhummer.
     
  16. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    I re reversed the cap. the hum is a tad lower, and when balance is centered you don't hear it.....But I lost a channel's volume....I have to raise the vol. pretty hight to get some...
     
  17. gadget73

    gadget73 junk junkie Subscriber

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    Does it stop humming with the bottom plate on? If so, put the bottom on :)

    Dead channel sounds like a connection is loose somewhere, or maybe a terminal got bent over to ground.
     
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  18. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    LOL...I did think about the bottom...correct. it is off for now...I will put it on...
     
  19. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    Hum is gone!! Thank goodness for bottom plates!!!!
     
  20. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    Now an output tube is redplating!! damn it

    It doesn't follow the tube....its something underneath.
     

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