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Thread: Yamaha Amp

  1. #1

    Yamaha Amp

    Yamaha Amp Post #1
    Hi everyone I have a problem with a Yamaha pc1002 power amp, it works on one channel only, the protection led is on.
    When i measure the idle current and dc offset they are correct and i can adjust them on both boards.
    This amp has a switch on the back to change from stereo to mono, when switched to mono the volume control for channel A works (it's channel A that doesn't work) in stereo mode.
    There are two relays one for each channel channel B relay clicks in but channel A relay doesn't, i tested the relay on a seperate power supply and it worked, the relay driver ic is a TA1317P sil 9 pin ic.
    Can anyone give me any advice please.

    Thanks in advance mick.

  2. #2
    Senior Member SC358's Avatar
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    Hello mick -
    Well since you've gone to the trouble of opening it up and pulling out the relay to test it, have you tried to get a schematic from Yamaha yet?
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  3. #3

    Yamaha amp

    Hi thanks for your reply, yes i have got hold of a schematic.
    And when i checked it out i found that the relay driver ic had been replaced with a dual op amp, i sent off for the right chip and installed it and now the amp works fine, i am not sure how the wrong ic ever managed to operate one of the relays but it did.

    Anyway thanks again mick.

  4. #4

    Yamaha amp

    Hi thanks for your reply, yes i have got hold of a schematic.
    And when i checked it out i found that the relay driver ic had been replaced with a dual op amp, i sent off for the right chip and installed it and now the amp works fine, i am not sure how the wrong ic ever managed to operate one of the relays but it did.
    Also the schematic is printed wrong the TA1317P is a TA7317P.
    Anyway thanks again mick.

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