Re: Problem: Sansui 9090 Protector Light Flashing Red

Discussion in 'Electronic Repair' started by Mark D. Zacharias, Jul 30, 2003.

  1. Probably wasted advice. This fellows obviously not a tech; the chances of
    him fixing it himself are remote. Probably just too cheap to pay to get it
    fixed.

    Mark Z.


    <> wrote in message
    news:...
    > wrote:
    > >
    > > Hi,
    > >
    > > Today I turned on the Sansui 9090 and the flashing red protector light

    next to
    > > the power button continuously flashed and the stereo never did go on.

    The tuner
    > > seemed to be picking up signals, as evidenced by the signal meter, but

    the
    > > sound output meters registered zero and no sound came from the speakers.

    Usually
    > > the light flashes red for a few seconds, turns green and then the tuner

    and
    > > stereo activates. Can someone tell me what the cause might be and if

    there is a
    > > simple fix?
    > >

    >
    > The protector is detecting excessive DC voltage from at least one of the
    > power amplifier output stages. It could be a leaky transistor, open
    > resistor, etc. on one of the channels or its the protector itself. It's
    > not likely that both channels will fail at the same time so your best
    > bet is measure for unusually high DC voltage on the relay protector's
    > power amp side. Once the faulty channel is isolated you can do voltage
    > comparison with the good one but before that check for physical signs,
    > see my last paragraph below.
    >
    > I assume that you've checked for normal power supply voltages. Without a
    > schematic, the DC voltage across the big filter capacitors should be
    > less but not half the quoted working voltage marking.
    >
    > With the receiver's age of ~1977, I strongly suggest you to check for
    > cold/cracked solder joints on hot spots like diodes, high power
    > resistors and transistors. Usually a darkened PCB would indicate hot
    > spots. Check for high ESR or dried up capacitors near this area as well.
    > Doing this will save you a lot of headaches later on any recurring
    > faults.
    >
    > > I don't have a manual for the unit, and have no idea what the protector

    light is
    > > for. Can someone tell me where to obtain a manual?
    > >
    > > Thanks.
    > > George

    >
    Mark D. Zacharias, Jul 30, 2003
    #1
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