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Thread: IBM 5150 troubleshooting

  1. #11
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    So I opened up the power supply to find leaked capacitors. Guess I'll start working on those, then!

  2. #12
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    Quote Originally Posted by RC14 View Post
    The video card I am confused by, as it has (what I think) is a CGA port as well as a much longer port that I don't recognize.
    Provide a photo of it.

    Quote Originally Posted by RC14 View Post
    and then smoke from the PSU. I don't really know what's going on, but I'll take a look at the inside of the power supply. Any thoughts? I get the beep after about 15 seconds and it's only when left running for a few minutes that I get the smoke.
    A possibility:

    The 5150's PSU contains a few line suppression capacitors. Sometimes, one ruptures, releasing smoke and odour.
    This often confuses people, because the power supply continues to operate (i.e. the smoke means something in the PSU failed, but the PSU is still working).
    See the 'Line Suppression Capacitor' section of [here].

    Are you sure that the source of the smoke is the PSU, and not smoke sucked into the PSU ?

    Quote Originally Posted by RC14 View Post
    Just an update: I've tested out the minimum diagnostic configuration, and now I'm getting a short beep ... I get the beep after about 15 seconds ...
    A short beep when in the minimum diagnostic configuration (MDC) ? In the MDC configuration, expected is a series of beeps, 1 long then 2 short.

  3. #13
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    A warning, from [here]:

    Aged tantalum capacitors are known to explode. That has happened to me many times, particularly when I have acquired something that has not been powered on in years. If the motherboard, or expansion cards, are exposed to your face when you power them on, then consider wearing eye protection.

  4. #14
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    Quote Originally Posted by RC14 View Post
    Also, extra information: the monitor that came with the computer has a few pins broken off the connector, so I haven't been able to use it
    Broken off, or not present ?

    For example:
    * MDA does not use pins 3, 4, and 5. In the 9-pin connector of my IBM MDA monitor (IBM 5151), those pins are not present.
    * CGA does not use pin 7. In the 9-pin connector on my IBM CGA monitor (IBM 5153), pin 7 is not present.

  5. #15
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    Quote Originally Posted by modem7 View Post
    The 5150's PSU contains a few line suppression capacitors
    Hmm, I don't see any - maybe it's a third party power supply?

    Quote Originally Posted by modem7 View Post
    Are you sure that the source of the smoke is the PSU, and not smoke sucked into the PSU ?
    Yes, I'm quite sure - the smoke was coming straight out of the PSU vent.

    Quote Originally Posted by modem7 View Post
    A short beep when in the minimum diagnostic configuration (MDC) ? In the MDC configuration, expected is a series of beeps, 1 long then 2 short.
    That's the other thing that I'm confused by - I assume that the faulty power supply caused it to perform oddly, but something on the motherboard could also be messed up.

    Quote Originally Posted by modem7 View Post
    Broken off, or not present ?
    Ah, I'll have to take a look.

  6. #16
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    Quote Originally Posted by modem7 View Post
    MDA does not use pins 3, 4, and 5. In the 9-pin connector of my IBM MDA monitor (IBM 5151), those pins are not present.
    That's what it is - thank you!

    I also figured I'd attach some photos of the PSU. I think the capacitors are leaking, but it may just be some sort of glue. Also, R19 appears to be cut, but intentionally (maybe as a switch for input voltages). Again, I don't see any line suppression capacitors, but that just may be me and my lack of experience. Nothing appears to be burnt, however, which I don't really understand it has at least smoked twice, and gave out enough smoke for me to notice. Thank you so much for your help! IMG_4398.jpgIMG_7198.jpgIMG_8904.jpg

  7. #17
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    IT WORKS! I don't know what I was thinking, but I decided to power it on again. Maybe it was dusty in the PSU and I dispelled it? I don't really know, but it isn't smoking anymore and I was able to start putting cards back in.

  8. #18
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    Quote Originally Posted by RC14 View Post
    I also figured I'd attach some photos of the PSU. I think the capacitors are leaking, but it may just be some sort of glue.
    Yes, under the large and medium sized aluminium electrolytic capacitors is glue.

    Quote Originally Posted by RC14 View Post
    Hmm, I don't see any - maybe it's a third party power supply?
    Quote Originally Posted by RC14 View Post
    Again, I don't see any line suppression capacitors, but that just may be me and my lack of experience.
    Line suppression capacitors are supplied in various forms. In your PSU, some of the brown/blue capacitors may be performing the function.

    Quote Originally Posted by RC14 View Post
    IT WORKS!
    Congratulations.

  9. #19
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    Quote Originally Posted by modem7 View Post
    Congratulations.
    Haha I've probably just put off solving the real problem until later, but, for now, it appears to work fine. Again, thank you!

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