CA-273 Large Capacitor Source?

Discussion in 'Fisher' started by mncorrado, Jan 6, 2018.

  1. mncorrado

    mncorrado New Member

    Messages:
    6
    Location:
    St. Paul MN
    I am thinking about re-capping my CA-273. I have a small issue in trying to find a source for the CA37 and CA38 on the Main Supply P.C.B Assembly.

    7500uF 75V

    Can't seem to find a source for these. I have checked DigiKey and Mouser. Any ideas? Or are there any alternatives for a difference capacitor that might work as good or better?

    Thanks!
     
  2. UncleBingo

    UncleBingo AK Subscriber Subscriber

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    296
  3. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

    Messages:
    20,459
    Location:
    Glen Burnie Md.
    Last edited: Jan 8, 2018
  4. mncorrado

    mncorrado New Member

    Messages:
    6
    Location:
    St. Paul MN
    Thanks! That was exactly the information I was looking for. Given the age of the unit is it a given I should replace them? The CA-273 works well though after it has been powered on and playing for 30-60 minutes I will get some scratchy noise from my speakers. Could this likely be related to old capacitors in the amp?
     
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  5. larryderouin

    larryderouin You can be sure if it's Westinghouse??????? Subscriber

    Messages:
    20,459
    Location:
    Glen Burnie Md.
    Could very well be dirty contacts in the switches and pots on the front end. Pull the face off and clean all of them with DeOxit D-5 and follow up with Either Faderlube (DeOxit F-5) or CRC 626 electronics lube. Do that 1st to rule them out. Then if you get scratchy noises, get a can of air (dust remover stuff for keyboards) and with the can upside down give each of the transistors in the amp section a very short squirt. Wait between transistors. If th scratchiness stops when hitting a certain transistor, replace it and it's mirror part on the opposite channel.

    Fix the problem 1st. When it's running 100% with no problems THEN go ahead and recap the whole thing. Do the Main Filter caps LAST. Electrolytic caps have an electrolyte (liquid) in them. The bigger the cap the more electrolyte. This electrolyte evaporates over time, more so in small caps that are exposed constantly to resistor and transistor heat. The Main's usually won't go bad as fast as the little caps, which is why changing them last is ok if they are working fine (not getting hot by themselves, and not puking from the vent).
     
    Last edited: Jan 8, 2018
  6. mncorrado

    mncorrado New Member

    Messages:
    6
    Location:
    St. Paul MN
    Thanks! I won't be able to get going on this for a few weeks but looking forward to the experience.
     

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