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Has anyone had this issue with a 4 pin tube socket?

Discussion in 'Tube Audio' started by Kennyg2209, Sep 15, 2018.

  1. Kennyg2209

    Kennyg2209 Active Member

    Messages:
    147
    Location:
    Pittsburgh, Pa
    I recently finished my test circuit for my first 2A3 tube amp build. All my voltages where close but the output tube B+ were a little different. I checked the temperature on all my resistors and the cathode bias resistor on the one output tube was hot. I checked the voltage across it and it was 110v. It should have been 45v. After check all my values and connections and everything being okay, I narrowed the problem down to resistance from the grid to ground was off. I disconnected all the wires going to the 2A3, and still had 35k ohms between the grid and plate. I removed both sockets, and removed the tubes. Then the socket in question still had anywhere from 700k up to 30meg. Between any of the pin sockets. The readings were always different. The other socket had no continuity They were brand new sockets . Has anyone else had this problem before? 20180915_213707.jpg
     
    Last edited: Sep 15, 2018

     

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  2. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,751
    Location:
    Southern NJ
    not on new sockets, but I have with crappy wafer sockets or things that have been overheated and abused. Not just dirt between the terminals is it?
     
  3. Kennyg2209

    Kennyg2209 Active Member

    Messages:
    147
    Location:
    Pittsburgh, Pa
    I even tried washing it with soap and water. I don't understand. I'm not sure how far the mounting plate is in the plastic . The pins are 1/2 inch apart. It took a bit to figure out that was the problem.
     
  4. BillWojo

    BillWojo AK Subscriber Subscriber

    Messages:
    2,748
    Location:
    Burlington, NJ
    I would scrap both sockets and get some high quality ones. Where did you get these?

    BillWojo
     
  5. knockbill

    knockbill Addicted Member

    Messages:
    7,782
    Location:
    SE PA
    +1... Amphenol and Cinch sockets are all over hamfests and radio shows...
     
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  6. Kennyg2209

    Kennyg2209 Active Member

    Messages:
    147
    Location:
    Pittsburgh, Pa
    I finally figured out what was going on. The plastic housing actually became conductive somehow. I cleaned it previously with soap and water, then tried cleaning it with a non conductive contact cleaner, and it's still conductive. Anywhere you touch the plastic there is continuity. Probably one in a million . I have others that are fine. 20180916_163748.jpg
     

     

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  7. BillWojo

    BillWojo AK Subscriber Subscriber

    Messages:
    2,748
    Location:
    Burlington, NJ
    Who mfg these things? No way should that plastic be conductive. Sorry but I would throw the whole lot of them out. If it's not a coating and it's in the plastic than the only thing I can think of is contaminated plastic in the injection molding machine. Maybe runners were never properly cleaned out when the molds were changed. Either way, I wouldn't trust any of them. There could be more conductive material mixed in the other parts.

    BillWojo
     
  8. Kennyg2209

    Kennyg2209 Active Member

    Messages:
    147
    Location:
    Pittsburgh, Pa
    I totally agree. It had to be during production. There's no markings on them. Don't know the manufacturer, They seem to be very well made. The other ones that are not conductive will not become conductive.
     

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