SX-1080.... Is this an issue?

Discussion in 'Pioneer Audio' started by TinCanAlley, Apr 17, 2017.

  1. TinCanAlley

    TinCanAlley Duck, you sucker! Subscriber

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    So Cal, CA
    Okay, something odd is happening upon power-down of my 1080. When I turn it on, the protection relay clicks after about 5 seconds. This is normal and has always been. What isn't normal happens during the power down. No matter what function it is in (AUX, Phono, FM, etc.) when I turn it off, there is a click and the "stereo" indicator light flashes. Unless I'm losing my mind, this isn't supposed to happen and I'm pretty sure I'd remember seeing it over the many years it has been in service.

    So, is this normal? Is the click the protection relay releasing? And what about the indicator light flashing?

    Other than that, there are no other issues (if this one is even an issue).

    Thanks
     
  2. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

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    I would check the PS voltages. Pin 18 for 13.5v (tuner) and pin 19 for the 7.5v that powers the indicators.
    The circuit is common to both the "Stereo" light and the tuner. The 7.5v's is derived from the 13.5v tuner supply.
    The stereo light works on a voltage potential and a slight variance in voltage can mess with it.
    The indicator is controlled by the PA1001 chip in the tuner. All the more reason to investigate this issue as soon as possible.
     
    Last edited: Apr 17, 2017
  3. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    Zeb; It sounds like the problem lies in the grab and release part of the Protection circuit governing the relay action. I remember a similar problem in either a x50 or x80 model a few years ago. The relay is releasing a fraction of a second too late. The OP should also rebuild the protection board as outlined in the sx-1080 rehab threads.

    Tincan; The click heard at power down is the relay. Because the times are too close to note, without numerous stop watches tied in to the circuit, You won't be able to tell that it's opening a fraction too late. But the symptoms lead in that direction. Rebuild the protection circuit (about a 1/2 dozen caps and 3-4 transistors, plus a 1n4004 if they didn't add the flyback diode.
     
  4. TinCanAlley

    TinCanAlley Duck, you sucker! Subscriber

    Messages:
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    Location:
    So Cal, CA
    I recapped the protection a few years back, but stopped there. I guess I can replace other pieces as well. I'll pull out the list and get an order going.

    When I have it down again, I will measure the voltages on the pins supply the lights.
     

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