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Thread: Ibm pc 5150a..... Possibly a pre-release build???

  1. #11

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    Quote Originally Posted by billdeg View Post
    If you get $150 be happy, or put $200 into it and sell for $700.
    For $150, I think I'll part it out... If I sold the motherboard, power supply, FDD controller card for $50 each... everything else would be gravy. or maybe I should just keep it.... I'm more confused all the time!

  2. #12
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    Quote Originally Posted by PCFreek View Post
    Which one is the hard drive?
    I was wondering the same thing...

  3. #13

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    Disk drive... OK... I thought I was missing something. I knew that as a senior member of this forum, you probably know your stuff!!

    I am still curious about 2 things...

    1.) any thoughts on the age of this?

    2.) I am on the fence about keeping it. What other parts are not original? If I kept it, I would probably leave the U33 chip alone, and use these disk drives, and leave the SixPak card in which would only leave me in need of a video card. Am I missing something else that stands out as not original? I am not so familiar with these so I could use advice. Thanks!

  4. #14

    Default Power supply issues

    Here are some pics of the power supply. Does anyone see any obvious cause of a failure?

    Attachment 12642Attachment 12643Attachment 12644Attachment 12645Attachment 12646

  5. #15
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    Quote Originally Posted by PCFreek View Post
    Here are some pics of the power supply. Does anyone see any obvious cause of a failure?
    You didn't say what the problem is. Right off the top of my head, though--if the fan doesn't spin, check the internal fuse. If the fan spins, but no power, you'll probably want to re-cap the thing.

    Didn't the earliest 5150s come with a blue floppy cable?

  6. #16
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    I have two of the 5150A's with bad power supplies. It's probably the caps but I wonder if there was something else that was an issue with these things? I think there was something with the first rev power supply, because every one I have had other than these two have worked perfectly. I want to fix these things when I have time and a place to work on them. My machines are from about the same time as yours, by the way. One is serial number 108666 and the other is 111331.

  7. #17
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    I've actually seen that keyboard connector before, on the IBM EMR (not EMR II) keyboard. While that doesn't seem to be the same keyboard (that lacks a grounding strap and I doubt the guts on the inside are covered in white stuff), it is, for the most part, the same as this one.


  8. #18

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    I think you have a early but not pre-production unit. It has been upgraded over time, which is what everyone with a IBM 5150 did. Most 5150s were used for 7-10 years. There were many in use into the 90's. Yours probably "died" after a long life.
    @ BillDeg:
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  9. #19

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    Quote Originally Posted by Chuck(G) View Post
    You didn't say what the problem is. Right off the top of my head, though--if the fan doesn't spin, check the internal fuse. If the fan spins, but no power, you'll probably want to re-cap the thing.
    It was stated earlier in the post... When I switch the power on, there is an immediate flash of power (+10.5V, -10.5V, and 5.1V)... which quickly drops to below 2v. Or was it +10.5V, +5.1V and -5.1V??? I dont remember. this is from memory.

  10. #20

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    Quote Originally Posted by Chuck(G) View Post
    You didn't say what the problem is. Right off the top of my head, though--if the fan doesn't spin, check the internal fuse. If the fan spins, but no power, you'll probably want to re-cap the thing.
    YES!! fan spins fine and is nice and quiet, but as stated above, the voltage is unstable dropping quickly from 10.5V to less than 2V on the red wires when not attached to the motherboard

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