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Diode Questions- Attempt at Vintage Turntable Resurrection

Discussion in 'Troubleshooting and Repair' started by Blake94, Nov 16, 2019.

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  1. Blake94

    Blake94

    9
    1
    Apr 22, 2017
    Hello!

    A couple weeks ago, a coworker of mine gave me four turntables that he had lying around after I mentioned I wanted to get into vinyl. They are all in various states of repair. Without getting too ramble-y, I fixed one, but the nicest one he gave me has me vexed. I've asked around at Vinyl Engine, but I think that this would be a better area to pose my question, since this is getting more into the weeds. And I'll be completely honest here, I'm learning everything as I go.

    It's a JVC QL-F4. The service manual is too large to attach here, but I don't think it will be necessary. When I plug the turntable in, the platter essentially twitches. It starts to rotate without being prompted to do so, but quickly stops, and won't respond otherwise.

    Upon opening it up, I found several electrolytic capacitors that had leaked all over the board. I replaced those today. One diode that was pretty well covered in the black gunk broke as I tried to clean it. I have left it for now. Another appeared to be already broken. The turntable continues to behave the same way.

    The diodes are a 1S2743 silicon diode and an RD5-6EC zener diode.

    My question is in two parts: What does the actual issue sound symptomatic of? I am aware that with broken diodes, it won't work right, but does a brief, initial power up sound symptomatic of faulty diodes? If not what might it be?

    Secondly, how would I go about finding replacements for these diodes? They are both discontinued. I have found several different diodes that claim to be the functional equivalent of these diodes, but the values are different for each one. How will I know that I won't fry my turntable?

    Thanks.
     
  2. Ylli

    Ylli

    271
    72
    Jun 19, 2018
    The Zener is a 1N5232B. Most likely, a 1N4148 will work fine as a replacement for the 1S2743.
     
  3. Blake94

    Blake94

    9
    1
    Apr 22, 2017
  4. Tha fios agaibh

    Tha fios agaibh

    2,083
    694
    Aug 11, 2014
    Don't you mean 1S2473?
     
  5. bertus

    bertus

    346
    112
    Nov 8, 2019

    Attached Files:

    Last edited: Nov 25, 2019
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