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Thread: Zeos 386 (not laptop)

  1. #1

    Question Zeos 386 (not laptop)

    Hi, I bought a vintage computer on eBay called a ZEOS 386, but it isn't a laptop, like what I've heard from everyone else. This is what it looks like:
    zeos.jpg
    The motherboard is a standard AT clone motherboard with a 386 and a 387 as well. When I flip the switch, all I hear is buzzing when connected to the motherboard. Otherwise, the PSU works. Have any of you had the same problem as me? The PSU is also in AT form factor.

  2. #2

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    Quote Originally Posted by ScreenGems98 View Post
    When I flip the switch, all I hear is buzzing when connected to the motherboard. Otherwise, the PSU works.
    Buzzing is never a good sign. How are you able to verify the PSU is OK? Since it's AT form-factor, I'd take it (the MB) to another AT PSU and try it there. From the looks of the machine it appears to have been treated quite roughly; hope you didn't invest much....

  3. #3
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    I thought AT power supplies would trip if they were grounding out. Also make sure the motherboard connectors are connected right. Black and Black and you're on track. Red and Red and you are dead.

  4. #4

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    I have had AT power supplies make a buzzing noise when they short out. If the PSU works only when not connected to the motherboard then you may have a shorted capacitor. Or like flashedbios2012 suggested you may have your motherboard power connectors reversed.

  5. #5
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    Could the buzzing be the BIOS counting through the memory? Some BIOSes make noises like that which are supposed to be comforting to hear as it works to figure out how much memory the machine has. [this is admittedly a longshot theory!] I'm assuming you have not hooked up a monitor to it?

    I'd pull all the cards out as well as the memory, unless the memory is DIPP packaged and not on DIMMs. Power it up and it should beep at you.
    I'd then get an ISA POST card and see if you see any numbers on it.

    As a former ZEOS employee, I feel somewhat bonded to these old guys and want to help. I'd even be willing to mail you a POST card as I have a spare or two.

  6. #6
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    Quote Originally Posted by hargle View Post
    Could the buzzing be the BIOS counting through the memory? Some BIOSes make noises like that which are supposed to be comforting to hear as it works to figure out how much memory the machine has.
    On most 386 speed machines with that type of BIOS that I have seen, that is more of a ticking. I was sort of under the impressions they used similar code in to the Pentium era where it sounded more like a buzzing. Of course, some BIOSes may have done things differently and had a more rapid ticking/buzzing.

    Still, where is the buzzing coming from?

    In a machine of that condition, I would start with a good disassembly, visual inspection, and cleaning. Make sure the motherboard has not warped or mis-mounted and shorting against the case. Also make sure all cards are inserted properly and start with only the minimum.

    It could be a shorted tantalum capacitor. If bad ones don't go boom, they can short and prevent power up.

    Some pictures of the insides might help.

  7. #7

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    I have a similar vintage but nameless clone which emits a buzz. But if you wait long enough on mine, it becomes evident that the buzz is a very low frequency beep as part of the error diagnostic beeps.

    But that's less likely in my opinion than a shorted motherboard (or peripheral).

  8. #8
    Join Date
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    Quote Originally Posted by ScreenGems98 View Post
    Hi, I bought a vintage computer on eBay called a ZEOS 386, but it isn't a laptop, like what I've heard from everyone else. This is what it looks like:
    zeos.jpg
    The motherboard is a standard AT clone motherboard with a 386 and a 387 as well. When I flip the switch, all I hear is buzzing when connected to the motherboard. Otherwise, the PSU works. Have any of you had the same problem as me? The PSU is also in AT form factor.
    I looked at that on eBay. Just looked too beat up to take a chance on.

  9. #9

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    Hi, all!

    Thanks for responding. The buzzing is coming from the PSU. I tested it to run a hard disk and it runs fine. It's definitely the motherboard, since other PSUs don't work on it. I've tested the capacitors on it and the power connections from the pins with a digital multimeter. I still don't know whats wrong. The motherboard is a generic 386 motherboard from a company called "Mylex". Any suggestions?

  10. #10

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    Could you send one? Or at least HD pictures? It might help. Thanks!

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