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Yamaha Rx-900u delayed relay click

Discussion in 'Yamaha' started by Odizzieus, Aug 6, 2018.

  1. Odizzieus

    Odizzieus Member

    Messages:
    69
    When I turn on the receiver for the first time in a day, it takes about 15 minutes before the relay clicks. If I turn off the receiver for an hour or two, the relay still takes time to click. If I turn it off and then back on, it clicks in about 10 seconds
     

     

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  2. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,906
    Location:
    Fort Dodge, Iowa
    There is probably a small dried up capacitor in the protect circuit that's responsible for the RC time constant that establishes the delay time.
     
  3. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,906
    Location:
    Fort Dodge, Iowa
    Look for C190 220µf/6.3 vdc it should be located pretty close to the protect relay.
     
    rcs16 likes this.
  4. rcs16

    rcs16 Super Member

    Messages:
    3,905
    Location:
    Baldwin, Ontario, Canada
    This unit is fresh on my mind after I re-built an amp channel, I found it easy to work on, take the top and bottom covers off, flip so you have access to the bottom. The component layout is shown from the copper side. Leads are auto inserted, so they are kinked, need to be straighten out with the hot iron first. pre-tin first before I remove the solder. Even after you remove the solder, use some very small needle nose pliers to straighten the leads, then they fall out of the holes with no damage.

    Good luck, I hope it is that ecap.
     
  5. Odizzieus

    Odizzieus Member

    Messages:
    69
    My replacement resistor comes today. Before I blew it like an idiot, the unit still didn’t click after a few seconds
     
  6. rcs16

    rcs16 Super Member

    Messages:
    3,905
    Location:
    Baldwin, Ontario, Canada
    capacitor C190?
     

     

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  7. Odizzieus

    Odizzieus Member

    Messages:
    69
    Yeah, I need to replace transistor q140 cause it’s fried, but after I fix that I’ll see what happens again

    Oh wait no, c190 didn’t blow. I blew a resistor.
     
  8. rcs16

    rcs16 Super Member

    Messages:
    3,905
    Location:
    Baldwin, Ontario, Canada
    You have two threads going for the same amp. This does not help to solve your problems.
     
  9. Odizzieus

    Odizzieus Member

    Messages:
    69
    I have two different problems, I already know what I need to replace to get the amp working again that’s not the issue, the issue is that the relay still doesn’t click shortly after startup. Is there anything else that can affect the timing
     
  10. rcs16

    rcs16 Super Member

    Messages:
    3,905
    Location:
    Baldwin, Ontario, Canada
    It might be the amp section that is causing this relay delayed turn-on issue. look at the voltages around Q148,149
     
  11. mbz

    mbz AK Subscriber Subscriber

    Messages:
    2,084
    Location:
    Melbourne, Victoria
    Did you replace C190. As mentioned it is part of the timing for relay activation. It is a 6.3Vdc item, such low voltage caps generally have a
    bad history of failing. If the cap is leaking, it will "never" charge up. Next step would be to measure dc offset to confirm ok then look for other
    failed components in protection circuit.
     

     

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  12. Odizzieus

    Odizzieus Member

    Messages:
    69
    C190 was replaced with no result
     
  13. mbz

    mbz AK Subscriber Subscriber

    Messages:
    2,084
    Location:
    Melbourne, Victoria
    enerally, the two scenarios are,
    - excessive dc voltage on speaker line so protection circuit does
    not operate the speaker relay
    - failure (component/conncetion,,,) in the protection circuit.

    Measure dc voltage, black probe connected to GND/Chassis at both sides
    of R283, repeat for both sides of R284,285,286 as per pix

    upload_2018-8-22_13-41-7.png
     

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