Re: Tried to recap a tube receiver, and failed.



Derwin wrote:
I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn it on it starts playing music for a few seconds after it warms up, then the music fades out and and hum takes over. I don't really know what I'm doing, and the wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced the caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps, and I'm wondering if the value difference, added up over 8 caps would make a difference? Other than that, does anyone have any advice based on my description of the unit's behavior? Any comments whatsoever might be helpful..


Obviously what you did caused the problem. Check for cold solder
joints and inadvertent connections via solder flash. If you have
enough information (e.g. a detailed log of what you did, or
before/after photos), go back and recheck your work.

Did it look like spaghetti before you started?

From your description, it sounds like maybe it's drawing more current
now than before, so that the power supply capacitors are no longer
adequate. Does it have a rectifier tube in the power supply? Is it
glowing red? Perhaps you've dramatically changed the bias point in
the output stage by some misconnection.

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Relevant Pages

  • Re: Tried to recap a tube receiver, and failed.
    ... caps, and I'm wondering if the value difference, added up over 8 caps ... I was probably repairing tube ... Or maybe we have different ideas of what spaghetti looks like. ... I was sent a "replacement". ...
    (sci.electronics.repair)
  • Re: Tried to recap a tube receiver, and failed.
    ... Why are you even replying if you obviously have never looked inside an old tube amp? ... Or maybe we have different ideas of what spaghetti looks like. ... All the caps I replaced are connected exactly where they were before I replaced them. ... Now perhaps you will be able to envision the 'spaghetti' wiring that a circuit not build on a PCB will look like.. ...
    (sci.electronics.repair)
  • Re: Tried to recap a tube receiver, and failed.
    ... fades out and and hum takes over. ... wiring inside looks like a mess of spaghetti. ... caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper ...
    (sci.electronics.repair)
  • Re: Tried to recap a tube receiver, and failed.
    ... wiring inside looks like a mess of spaghetti. ... caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper ... Old equipment wiring does look like spaghetti compared to PCB construction. ... DId he replace the electrolytic caps as well? ...
    (sci.electronics.repair)
  • Re: Tried to recap a tube receiver, and failed.
    ... on it starts playing music for a few seconds after it warms up, then the music fades out and and hum takes over. ... I'm pretty sure I replaced the caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps, and I'm wondering if the value difference, added up over 8 caps would make a difference? ...
    (sci.electronics.repair)

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