Yamaha TX-1000U No FM Signal

Discussion in 'Tuners' started by mea2112, Apr 12, 2018.

  1. rcs16

    rcs16 Super Member

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    I was thinking the same to jumper out the PIN diodes in the front end.
     

     

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  2. mea2112

    mea2112 AK Subscriber Subscriber

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    Thanks again guys. I guess I have some catching up to do!
     
  3. mea2112

    mea2112 AK Subscriber Subscriber

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    Would one of you great teachers mind explaining how I could go about jumpering to the front-end to check the PIN diodes?
     
  4. rcs16

    rcs16 Super Member

    Messages:
    3,586
    Location:
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    Short D3 anode to D4 cathode, connect your antenna to "A",test
     
  5. mea2112

    mea2112 AK Subscriber Subscriber

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    Thanks.

    D3 and D4 are under copper-colored shield I'm guessing. How do you get that dang cover off? Best (only?) way to short D3 to D4?
     
  6. rcs16

    rcs16 Super Member

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    3,586
    Location:
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    I am not sure exactly how to dis-assemble the shield cover since I do not have one nor have I serviced one in the past. Sometimes they are friction fitted, in some cases they are soldered. Use a jumper wire with some grabber clips on both ends to apply the short.
     
    Last edited: May 13, 2018

     

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  7. mea2112

    mea2112 AK Subscriber Subscriber

    Messages:
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    Thanks. Power Supply test points measured -12V and +12.39V

    Finally got the shield cover off. Internal A/B antenna parts appear to be undamaged.


    20180513_211409.jpg 20180513_211459.jpg
    On to the D3/D4 diodes. Man, they are tiny! Like 3/16"? My small grabber clips are too big to grab onto the anode/cathode. Any other suggestions?
    Also, the point of shorting D3 and D4 is to bypass them or essentially remove them from the circuit right?
     
  8. rcs16

    rcs16 Super Member

    Messages:
    3,586
    Location:
    Baldwin, Ontario, Canada
    With power off you can do a DMM diode test on those diodes to see if they measure okay. D1-8
    need to get smaller grabber clips to get at the leads.
    You can also access the diodes from the solder side of the pcb.
    That is correct. You do not know if the diodes are open, short or okay, have to check them out.
     
  9. mea2112

    mea2112 AK Subscriber Subscriber

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    Thanks!
     

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