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Thread: Hello! I got a machine that was sold for parts! May need assistance?

  1. #31

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    Quote Originally Posted by GiGaBiTe View Post
    I can see it fine as well, something is wrong on your end.
    yes, obviously...

    Quote Originally Posted by Stone View Post
    I tried it with a proxy and it worked.
    It was Chrome on a Vista machine that must be too old to gain access to that site.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  2. #32

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    I didn't think about the power supply, but it was tested a bit. After I cleaned the motherboard, and was in the process of cleaning the case, I had the motherboard in here on my desk with a different PSU on it. I didn't test it for a massive long time, but I can try that and see if the issues persist. I will have to work on that tomorrow. But if the PSU is bad, the size and shape of the supply makes it difficult to replace, it's a strange LPX size. I can see the PSU as being bad as my 386 Legend 600X or SX, can't remember the PSU went out in that one too.

  3. #33
    Join Date
    Apr 2015
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    Quote Originally Posted by Nathanieltolb331 View Post
    But if the PSU is bad, the size and shape of the supply makes it difficult to replace, it's a strange LPX size.
    If it can't be repaired, then you can often shove the guts of another power supply inside. MicroATX power supplies fit in most anything that isn't a small form factor box. You just gotta work out new mounts for the PCB and make sure they're solid so nothing can short out.

  4. #34

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    I'm pretty certain that the power supply for the 386 can be fixed, I just don't know if I can do it. My skills with soldering and de-soldering are very basic. I want to improve them, and I have been successful at building boards, and I hope to do a snark barker board here soon. My fear is that I will disassemble the board, removed the caps, and then once that's done, I won't be able to remember what cap goes where. Even with detailed pictures and notes. Also, based on the size of these LPX power supplies, I'm not even sure I could fit a proper industrial Power supply in there. They are just pretty darn small.

  5. #35
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    Quote Originally Posted by Nathanieltolb331 View Post
    My fear is that I will disassemble the board, removed the caps, and then once that's done, I won't be able to remember what cap goes where. Even with detailed pictures and notes.
    Power supplies are not complicated, especially ancient ones from the 386 era. They're almost always silk screened with part designations on the PCB, so all you have to do is write the designation given for the component and its value. You'll then need to observe the orientation and make sure you put it back the right way around.

    Designations for parts are pretty standard, and they'll be numbered counting upward based on how many of the component are installed on the PCB.

    C - Capacitor
    L - Inductor
    Q - Transistor/Mosfet
    R - Resistor
    D - Diode

  6. #36
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    Sep 2008
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    SE MI
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    Quote Originally Posted by Nathanieltolb331 View Post
    I'm pretty certain that the power supply for the 386 can be fixed, I just don't know if I can do it. My skills with soldering and de-soldering are very basic. I want to improve them, and I have been successful at building boards, and I hope to do a snark barker board here soon. My fear is that I will disassemble the board, removed the caps, and then once that's done, I won't be able to remember what cap goes where. Even with detailed pictures and notes. Also, based on the size of these LPX power supplies, I'm not even sure I could fit a proper industrial Power supply in there. They are just pretty darn small.
    Check around town and see if someone still has a TV repair or small appliance shop up and running. Or - be patient and scrub eBay on a regular basis and look for a good used one.
    Surely not everyone was Kung-fu fighting

  7. #37

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    If you've got a pic and the specs of the PSU it might help in locating a suitable replacement. Is it an AT PSU?
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  8. #38

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    I don't think it's the PSU. I just pulled a working AT PSU that runs a Pentium 233MMX machine and plugged it into the board. After several minutes, the machine locks up. Upon reboot, the machine will post but will fail within just 2-3 minutes, and upon third reboot, it just sits at a black screen. I tried a combination to see if it was a setting that I had made mixed with other things, so external memory only, ISA video card instead of internal. All together with a known working PSU, and the machine still doesn't succeed at a post. At this point I have to think it's either an issue with a surface mount chip that's important, or the traces somewhere are damaged that I cannot see and it's causing the system to fail as it warms up. Oh, and in regards to having the PSU for the 386 repaired locally, I have called around to the local TV repair shops after my friend Ed Jeffries died to see if I could find someone else who could do solder work and board repair, but none of them would do it. Several of the shops said when they needed board work done, they sent it to Ed. So to get the PSU fixed I'm going to have to ship it somewhere. And in regards to Ebay, I have been watching it closely for one of the PSUs to show up, and I have not seen one in the past 2 years. So either they are terrible, which wouldn't be a surprise for a Packard Bell part, or just that no one scraps them. The 386 PSU is labeled as a Packard Bell PSU, but matches the same layout board wise and component wise as the PSU in the 486 that's giving me trouble, which is a DVE PSU. I tried to check the voltages coming out of the PSU with my multimeter, and everything appeared to be correct? However, since I don't have a lot of experience I'm not sure I was doing it right. I got +12.03V fairly stably, and + 4.96V to +5.01V. I don't even know if those numbers are okay honestly. I have a lot of books on the subject, but no time to read. My five year old daughter makes certain of that.
    Last edited by Nathanieltolb331; March 18th, 2020 at 10:26 AM. Reason: fixed typos, add addt'l information

  9. #39

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    It sure sounds like the PSU is not at fault. That woulda' been too easy, right?
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  10. #40

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    Quote Originally Posted by Stone View Post
    It sure sounds like the PSU is not at fault. That woulda' been too easy, right?
    Right. But based on what I am seeing on the screen, it would be indicative of something not being right voltage wise. I noticed today, if I looked carefully at the screen while it was running, there was an almost imperceptible brightening and darkening of the text and Packard Bell Logo. Almost like the voltages weren't right. Also using the references that someone gave me here, I checked the power good signal, and it was within the acceptable range. 4.35V. I just can't help but wonder if there's a chip that has corrosion damage I can't see, which is 1000% likely, or that somewhere the traces got damaged that I can't see. Is it possible that the board is de-laminating? Is that the correct term? Where the layers of the PCB start to fail and separate? The failure only occurs after the board warms up a bit, which makes me think that there is a bad contact on one or more of the surface mount chips on the board. I do not have the solder tip or the soldering skills to reflow all of the pins on the surface mount chips on this board. One chip with 8 legs? Maybe I could do that. The integrated video is like a 168 pin QFP chip. I have no skill for that. I did buy another Riser card and a replacement graphics chip, if that is what was wrong. However at this point I cannot tell.

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