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Technics SU-CH900 switching off

Discussion in 'Electronic Repair' started by Chris Hughes, May 16, 2004.

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  1. Chris Hughes

    Chris Hughes Guest

    I have a Technics SU-CH900 which is an amplifier module from a mini
    hi-fi. When I press the power button it frequently comes on then goes
    straight back off again. Recently, it blew the T1.6A fuse on the mains
    input. When switching the unit on, I've noticed that one of the relays
    (possibly RL701) makes a makes a short grating noise as opposed to a
    nice sharp 'click'. I have dismantled the relay and found only minimal
    carbon which I have cleaned off. I suspect mains smoothing capacitors
    (by the noise the relay makes) though my experience with audio
    electronics is very minimal.

    Does anyone have any pointers. Please let me know if I'm in the wrong
    newsgroup!

    Many thanks.
     
  2. Jerry G.

    Jerry G. Guest

    Did you check that any speaker wires are not shorted?

    It is possible that the main output IC's and their drivers may be going
    defective, and or some other support components.

    --

    Jerry G.
    =====


    I have a Technics SU-CH900 which is an amplifier module from a mini
    hi-fi. When I press the power button it frequently comes on then goes
    straight back off again. Recently, it blew the T1.6A fuse on the mains
    input. When switching the unit on, I've noticed that one of the relays
    (possibly RL701) makes a makes a short grating noise as opposed to a
    nice sharp 'click'. I have dismantled the relay and found only minimal
    carbon which I have cleaned off. I suspect mains smoothing capacitors
    (by the noise the relay makes) though my experience with audio
    electronics is very minimal.

    Does anyone have any pointers. Please let me know if I'm in the wrong
    newsgroup!

    Many thanks.
     
  3. Chris hughes

    Chris hughes Guest

    I have traced two faulty diodes in the PSU marked D709 and D710. They
    are transparent with a white band marking the cathode and a single
    green band around the middle. Now I am not used to component level
    stuff, does anyone know what these could be?
     
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