Trying to fix my 5C3 Deluxe (and some pics)

Discussion in 'Amp Tech Center' started by capohk, May 30, 2019.

  1. capohk

    capohk TDPRI Member

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    My beloved 1954 Deluxe has packed in so I am taking the opportunity to have a good look all around it. The serial number is 1984 as stamped on the chassis, written on the tube chart and also on a piece of what looks like masking tape inside the chassis with what looks like a name, but not very easy to read. The date code DC appears in a few different places making it March 1954. The codes on the Jensen P12R are 220344 and P12R C4897 3 which I think means it was likely made in the 44th week of 1953.

    It is a re-tweed (a pretty good job and kind of worn in now). A while ago a local tech changed the two core power lead to a three core with a proper safety earth and at the same time changed the electrolytics as a precaution. I think the speaker wire looks more modern as its a regular brown bit of hi-fi speaker lead and not the twisted black and white, but other than that I've always taken it for totally stock original.

    It sounds magic when it works. I baby it due to its age and rarely take it to gigs or practice, but I probably should just use it for what it was made for.

    Anyway, some pics for those interested. A bit of uniqueness is that the tube chart is hand modified in what I take to be the same pen as the serial number, making it something of a transition/prototype model. 6SC7 is crossed out and the two preamp tubes written in. I've followed the circuit layout and it follows the 5C3 layout exactly, other than the preamp tubes (and sockets obviously).

    I have tested all points to safety ground and eliminated the obvious, like speaker and guitar cables. The amp pulls current on my lightbulb limiter so no dead shorts. The pilot comes on and tubes glow, but there is nothing from the speaker, nada.

    Accepting the usual caveats about sticking my hand in a live amp, I'd love some advice on the order to diagnose the fault.

    Cheers

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    Oh, and the cockroaches have been at the speaker...

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  2. D'tar

    D'tar Tele-Afflicted

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    So whats the issue? It looks like fairly new e caps. You may only need new set of power tubes. Yours appear to be a mixed set anyway. Just glancing at your pics... The following throws a big red flag. It looks like you have no fuse protection. This is first on the list IMO. Hopefully the PT is OK! I would re do the power in/fuse/switch/pt connections. Maybe just the camera angle but needs verified!!!



    upload_2019-5-30_9-28-32.png
     
  3. D'tar

    D'tar Tele-Afflicted

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    That's not the rectifier tube in V4 is it?

    upload_2019-5-30_9-42-17.png
     
  4. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Good catches by @D'tar there :D

    Once those two things are verified and fixed, if necessary, voltages on all tube pins usually expose these issues pretty quick.
     
  5. capohk

    capohk TDPRI Member

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    Yes, that does look wrong.

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  6. capohk

    capohk TDPRI Member

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    Ha - no. Picture taken as I was swapping out tubes for known good ones. Rectifier is not installed in this pic. One 6V6 is an old RCA and the other is a JAN phillips.
     
  7. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

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    Always go for tubes first.
    Did you try another speaker?
    And that red one with the dink in it looks like a death cap. It should be disconnected if it goes to ground.
     
  8. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    This also should be known by this point, but don't go back to that "tech" either :D
     
    Nickfl and capohk like this.
  9. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

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    Some rough looking solders there...
     
  10. capohk

    capohk TDPRI Member

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    Yes. I think I will make a proper bolted eyelet safety ground and implement the power wiring arrangement from robrobs doc here (Thanks again Robrob!).
     
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