More amp trouble - second SOS!

Discussion in 'Amps & Cabs' started by RVA, Nov 14, 2015.

  1. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    I would also add as I believe is shown in the Premier Guitar video I first posted, as the safest rule of thumb, VERIFY presence of current, Discharge like they show with wire and resistor,,,have hand in pocket, plus always verify with meter that the caps are fully discharged. I once was working on a bathroom and had to deal with 2 electric circuits, one was 110 the other 220. I didn't have a tester to verify the breakers I switched off actually killed both circuits. Later after most of my work was done, I discovered the 220 was hot the whole time and I could have easily been zapped had I been unfortunate enough.
    After this, I now have the proper testers and VERIFY no current before working around house wiring etc.
     
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  2. 67plexi

    67plexi Well-Known Member

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    This is a 6L6GC amp Dumble low Plate Classic the power amp will work the same way.
    Pin #1 Phase Inverter to 5k1 resistor to pin #5
    Pin #2 & #7 filament AC voltage should read 3.2-3.4 VAC each leg.
    Pin#3 output transformer secondary Should read 500 volts Dc
    Pin#6 High voltage input should read 508 Volts DC also output transformer primary.
     

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    Last edited: Jan 22, 2016
  3. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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  4. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    67,,,,,,,, what are those blobs of opaque goop over various caps etc in the pictures from RVA? I used to have a Peavey Delta Blues and it had those same type blobs.
     
  5. RVA

    RVA Well-Known Member

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    I was wondering the same thing. I assumed that they were part of the build, which is reinforced since you had it.
     
  6. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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  7. syscokid

    syscokid Well-Known Member

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    They're there to keep the components stable from vibration and other movements.
     
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  8. syscokid

    syscokid Well-Known Member

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    Another way to this, is with a wire but no resistor. You'll be using one of the amps plate resistors to bleed off any current left in the circuit. One end goes to any bare metal spot on the chassis, or a built up grounding point. The other end goes to the first plate resistor in the circuit or Pin 1 at the first preamp tube.
    18WPlexi-Layout.jpg
     
  9. syscokid

    syscokid Well-Known Member

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    I found one of my own pics that shows this:
    IMG_1935.JPG
     
  10. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    That is exactly what I figured, Sysco, but wanted verification.
     
  11. 67plexi

    67plexi Well-Known Member

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    The clear goop on the filter board is hot glue nasty.
     
  12. syscokid

    syscokid Well-Known Member

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    Like the way you said dat! :naughty:
     
  13. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    Steve, can you explain what you mean here?

    "make sure that the grid resistor's read 470 ohms should be 5 watt"
     
  14. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    I think I fairly well understand what Uncle Doug is explaining about the various taps etc on the transformer in this video, plus the specs he discusses. But how does that correspond to your message to RVA about how you would walk thru testing the transformer, and the 8 pin socket etc?

     
  15. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    I have not viewed this whole set from Uncle Doug, but I suspect he illustrates things pretty well



     
    Last edited: Jan 22, 2016
  16. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    LOL @ Uncle doug @ 6:00 in part 2, " a bare fluttering of strings to ending up over here blasting till the neighbor's call the police"
     
  17. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    Sorry to seemingly flood the thread with how to videos, but I can't help but make suggestions to RVA and anyone else interested in the theory of amps and thus give you guys reference material to help understand just how amps work and thus what causes them not to work as well.

     
  18. 67plexi

    67plexi Well-Known Member

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    The standard Grid resistor on a 6L6GC is 470 ohm's or 470R Pin #4
    http://www.radiostation.ru/tubes/6L6GC-GE.pdf
    My wild guess a shorted out tube causing hum is the secondary filament supply is reading low under 6.3 VAC if so the power transformer is toast.
    Pin #2 & #7 8 pin socket and pin #4 #5 #9 on the 9 pin socket set your VOM to AC volts and read the voltage if your reading is like 4.2 VAC it's a shorted out power transformer.
     
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  19. RVA

    RVA Well-Known Member

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    OK, she is open and verified as discharged. I must say at this point that everyone's support, research and advice is quite extraordinary. I am touched more than you could image. OK, now for the tech:

    Interestingly, the brown 50V cap held the charge since I fired it up yesterday. I could not fully detach the PCB without considerably more dismantling, so I hope these suffice. It is nearby if you need anything specific. I took a picture of 2 orange drop cap and a round black cap simply because they looked noteworthy.

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    My most relevant observation is that the solder points of the caps look brown.
     
  20. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    RVA--I could not fully detach the PCB without considerably more dismantling,

    This is why when I went to try and fix the reverb in my Delta Blues, I cursed Peavey for how freaking much of a pain is was to disassemble the amp to get at anything.

    Now if only we can get your Peavey fixed for ya.
     

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