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Thread: Music - Sound Board not working - Can I test a CHIP?

  1. #41
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    Wotnot beat me to it.

    Check continuity between Pin 1 and the resistor and resistor and Pin 2

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    GT250 (27-05-24)



  • #42
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    Ok.
    It's working!
    I'm drained...!

    When I got back home, I sat down, and on Resch's advice I was convinced that Bev had put the wrong R in R16 200k and maybe R18 10k.
    So I snipped a leg off all the R's along that row to test.
    And they all read ok... Holy Moley! I'm gonna kill myself...!!

    Back to the blank PCB. PIN1 looked ok to the pads at the 200k and 10k. Beeped ok.

    PIN2 didn't beep at the nearest pad of the 200k. Huh?
    Didn't beep at the pad of the 10k...

    Checked the PIN2 leg of the LM to the other side (through base 8pin mount), and it was ok.

    But the beeping was ok from the pads sideways off PIN2.
    Anyway, so all in all, I realised that the track from PIN2 was not connecting to the pads of the 200k and 10k.

    I put a lead wire from the top of PIN1 on the LM and soldered it across the pads of the 200k and 10k. Bev was next to me. I plugged it in and it worked...!!

    No idea why the track was gone!
    Not going to unsolder anything around the LM to find out why...



    Resch's: Thank you so much for your guidance to lean me to check the V's in DC and AC around the LM.
    You obviously know about these LM358's.
    Wotnot: Your advice as always has been most helpful.

    I'm drained...!
    The PCB is, as Wotnot hates, is so black, it's virtually impossible to see any breaks etc.

    And here I am, venturing into the micro world of SMD stuff. Got the gear. Paid the dosh, and yet couldn't see/find a simple broken track on a bog standard PCB. LOL!
    Anyway, it all worked out.

    I do hope that other lurkers on this forum watch my antics and see this 'newbie', learning about the electronics world, helped along by wiser and far more experienced people than myself...

    All good fun:

    Cheers,
    GT250.

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    Reschs (27-05-24)

  • #43
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    I am guessing the track was damaged during the removal of the chip when it was mounted on the wrong side of the board.

    Great work in persevering with the fault finding.
    Last edited by Reschs; 27-05-24 at 11:31 PM.

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    GT250 (28-05-24)

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