1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

Cleaning up a Fisher 500C

Discussion in 'Fisher' started by Mikeorg, Sep 24, 2018.

  1. Mikeorg

    Mikeorg New Member

    Messages:
    43
    Location:
    OREGON
    I'm recaping a Fisher 500C receiver and need to know if I can use two 1000uf 50v capacitors for the large cap in the power section, I am keeping the selenium rectifier for the moment! someone replaced the large double can with junk...I don't know what was in it originally? Junk in second photo
     

    Attached Files:

     

    Please register to disable this ad.

  2. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,411
    Location:
    Melbourne, FL
    Hi Mikeorg,

    Your question would probably be better served in the Fisher section. You can ask for an admin to move it if you agree.

    The 1000uF caps sound way too big for the Fisher. I don't have a schematic handy, but you might be better served by keeping to the original values or a slight bump up, but not that much. Increasing the power supply caps by such a wide margin could cause problems. The guys in the Fisher area would certainly give you a more definitive answer.
     
    Mikeorg likes this.
  3. 604man

    604man Well-Known Member

    Messages:
    870
    The selenium rectifier has got to go....
     
    RUmad likes this.
  4. Mikeorg

    Mikeorg New Member

    Messages:
    43
    Location:
    OREGON
    Not yet it doesn't...
     
  5. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,411
    Location:
    Melbourne, FL
    Most of the Fishers of that vintage didn't come with a Selenium rectifier. I don't have a 400, but my other Fishers didn't originally have them.
     
  6. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,411
    Location:
    Melbourne, FL
    Oops. That certainly does look like a Selenium rectifier in your pic. I've never had one die, but I heard they really really stink when they do.
     

     

    Please register to disable this ad.

  7. RUmad

    RUmad AK Subscriber Subscriber

    Messages:
    942
    Location:
    New York
    That’s not the power section, it’s the negative bias supply. 10,000 is too high. Most people use two 1500uf caps there. Selenium doesn’t ‘have to’ go, but it should. It’s easy and cheap. Like my ex wife. And I don’t know what the lower blue cap in your picture is but the upper one is a Sprague atom, they aren’t junk. Try over in the Fisher section, you won’t be sorry.
     
    Mikeorg likes this.
  8. 604man

    604man Well-Known Member

    Messages:
    870
    I have a 500C that I rebuilt, The selenium provides bias for the 7591 output tubes
    you risk burning them up with low bias.

    As I recall bias should be -18 to -21 volts.
     
  9. Mikeorg

    Mikeorg New Member

    Messages:
    43
    Location:
    OREGON
    Thanks for the information RUmad I am a novice, I've gotten some Tube gear running very well but sometimes only by asking the stupid questions, I buy something find out what it was in it's original form and try to bring it back to life as it was, I will be changing out the selenium but need to learn to make a Diode rectifier first! thanks everyone!
     
    RUmad likes this.
  10. 604man

    604man Well-Known Member

    Messages:
    870
  11. Mikeorg

    Mikeorg New Member

    Messages:
    43
    Location:
    OREGON
    But what bridge -rectifier works with a 500-C Volts etc.etc?
     

     

    Please register to disable this ad.

  12. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,253
    Location:
    NYNY
    Check the stickies for a reference from Mouser. When Radio Shack was alive, the go-to part was a 8A 400 component which was WAAAAyyy more than what was needed. Anything from 6A to 8A and 400+ volts would suffice. Components intended to fail in over-current situations would be placed elsewhere during a thoughtful restoration.

    As to your original question, originally C-97 was a dual 1000uf 35v can. A pair of 1000uf 50v electrolytics would be perfect.
     
    Mikeorg likes this.
  13. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,253
    Location:
    NYNY
    For a couple of bucks, I would opt for a package component and be done with it.
     
    RUmad likes this.
  14. RUmad

    RUmad AK Subscriber Subscriber

    Messages:
    942
    Location:
    New York
    And right before radio shack died I bought out all the 8A bridges from two locations :naughty:
     
    Mikeorg likes this.
  15. Mikeorg

    Mikeorg New Member

    Messages:
    43
    Location:
    OREGON
    Thanks notdigital, I've ordered the 1000uf 50v capacitors I finally found it C-97 on my schematics, but please fill me in on as to what a package component is?
     
  16. Mikeorg

    Mikeorg New Member

    Messages:
    43
    Location:
    OREGON
    Is that what I am looking for an 8A bridge?
     

     

    Please register to disable this ad.

  17. RUmad

    RUmad AK Subscriber Subscriber

    Messages:
    942
    Location:
    New York
    A bridge rectifier, a package component, is one component that is essentially four diodes in one package. Like so

    CB06774A-A7F0-481F-8429-1A51F59A0617.jpeg
     
    Mikeorg likes this.
  18. Mikeorg

    Mikeorg New Member

    Messages:
    43
    Location:
    OREGON
    OK thats what I thought it was but wanted clarification...:thumbsup:
     
    RUmad likes this.
  19. Mikeorg

    Mikeorg New Member

    Messages:
    43
    Location:
    OREGON
    Would a 8A 600V Bridge rectifier work?
     
  20. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,253
    Location:
    NYNY
    A bit overkill but yes, it'll work.
     

Share This Page