1. Rest in Peace Paul (Kegger) If you would like to help the family in this time of great sorrow and need, you may donate on their GoFundme page: https://www.gofundme.com/mckechnie-medical-and-funeral-fund?
    Dismiss Notice

Pioneer SX-1080 slow to come out of speaker mute?

Discussion in 'Pioneer Audio' started by rocknroller, Jul 16, 2017 at 2:44 PM.

  1. rocknroller

    rocknroller Active Member

    Messages:
    135
    Takes about 8-9 seconds before speakers get unmuted after power on. Normal? I saw one other you tube video and it took the same, just seems like LONG time.
     
  2. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

    Messages:
    3,762
    Location:
    Las Vegas Nevada
    I would say it's on the long side by a few seconds.
    Note:
    This receiver has a soft start circuit which can add a second or two to the power up sequence.
    You would have to check the amps DC Balance and idles at power up and see if they take extra time to stabilize. If they come up even then the protection will engage but if one is lagging the protection has to wait for the slow channel to catch-up.
    A check of the power supply feeds might be in order. Checking to see if one supply is slow to come up to full voltage.
    The tone boards can cause delays as well. Try a power up with the tone in defeat or the rear jumpers removed.
    Sometimes the first power up of the day will be slow but subsequent power ups are quicker. This would be normal for an older original set.
    Another scenario; The timing capacitor in the protection circuit could be causing the delay. This is looked at only after all the other causes are sorted.

    Is the set functioning correctly? Does it go into protection when pushing the volume to high levels? Do the tone controls when selected on, cause any issues?
    If its operating without issues, it's probably best to leave it alone.
     
    Last edited: Jul 17, 2017 at 12:46 AM
  3. rocknroller

    rocknroller Active Member

    Messages:
    135
    Doesn't seem to make a difference if it's the first one or subsequent ones. If I power up, wait to come out of mute, turn off and back on again - same time- multiple times repeated. I haven't tried leaving it on for an extended period, then shutoff and quick back on though.
    I'm not clear on this comment though "You would have to check the amps DC Balance and idles at power up" - where specifically should I be checking and for what?
     
  4. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

    Messages:
    3,762
    Location:
    Las Vegas Nevada
    What about the other suggestion?
    Try powering up without the jumpers.
     
  5. rocknroller

    rocknroller Active Member

    Messages:
    135
    Attached is the protection circuit schematic and the readings at the various pins in Red. There is clearly some differences from the schematic. Most notable, -71 at pin 2 instead of -60, which seems a little too high and the Left and Right input pins (8 & 5 respectively) both start at -3 volts and count up through the 8 second startup but end at different values. Pin 8 (left) ends at -0.150 whereas pin 5 (right) ends at positive 0.33, roughly for those. Pin 10 is also a little higher at 80v vs 76v, but it seems the other areas might be more of concern?
     

    Attached Files:

  6. rocknroller

    rocknroller Active Member

    Messages:
    135
    Sorry for the delay in response - I'm responding to previous thread messages, then see ign these after.

    With jumpers out start to unmute is 7.X seconds, tone engaged or not. there might be up to 1/2 second difference but also just slow on my fingers to catch start/stop too.
    With jumpers IN, Tone out - 7.X seconds. With jumpers IN, TONE IN - 10 seconds.
     
  7. rocknroller

    rocknroller Active Member

    Messages:
    135
    Honestly have not pushed it yet or hooked up appropriate speakers to do so. Been chasing down other issues prior to this with lamps and meters (meter problem still not resolved) plus most of my testing is at night after wife asleep so that curtails any loud volume testing, but I will try to get something rigged up during the day to push it and see what happens. The service manual does state the startup time can be "several seconds" but they never qualify exactly what that is. 10 Seconds does operationally seem like a LONG time though. I hope the voltages I provided on the protection board help give a clue as to what might be happening.
     
  8. rocknroller

    rocknroller Active Member

    Messages:
    135
    No issues pushing it that I've found yet. I did go through the service manual and set the center voltage and idle current. Center voltage was about 1/4v on both channels (manual says set to 0v) and the idle current was quite low on one channel so raised that to 30mv (or as close as I could get) . No change on boot time. Although I can find lots of youtube video with sx-1080's. all except one already have the unit booted. The one i found previously also shows a 10 sec boot with the tone control IN, so I guess my assumption at this point is that is normal for this particular unit. Seems like the chances of both units having exactly the same boot time, and both be flawed the same way are rather small. Still - There is someone selling one on ebay and I've floated them a question as well.

    Now if I can just get this damn tuning meter consistency problem fixed....
     
  9. zebulon1

    zebulon1 Into Phase Linear's lately Subscriber

    Messages:
    3,762
    Location:
    Las Vegas Nevada
    It's not worth tearing into it. It's working fine.
    The idles and Balance are stable, all is good.
    The receiver does have a set of the 2sa726 transistors in the flat amp which is conditioning the signal all the time. These are known for causing a unstable DC Balance and when really bad, popping and snapping of the speakers.
     
    Last edited: Jul 18, 2017 at 3:52 AM
  10. mbz

    mbz Well-Known Member

    Messages:
    553
    Location:
    Melbourne, Victoria
    The service manual includes a description of the power ON sequence. Appears to be dependent on caps connected tp PA3004 pin 8
    ie C4, C5 (47/16v) to charge up. If you are concerned about the start up time and C4&C5 are original then replace. I would not be
    concerned about the 8-10 seconds, means transients have had plenty of time to settle, more concerned about other things, has
    the SX been recapped...
     

Share This Page