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Thread: Need replacement or reworked D12887 CMOS battery

  1. #1

    Default Need replacement or reworked D12887 CMOS battery

    Just when I had my DOS PC the way I wanted it and then the Dallas D12887 dies... I think it's soldered on the board without a socket... ugh. Anyone have modded D12997s with a battery socket or something?

  2. #2

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    How odd... it started working again. I know I should still replace it but... at least I can save BIOS now.

  3. #3
    Join Date
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    I assume you mean the DS1287 or DS12887. There are plenty of instructional sites on reworking one with a new battery. It's not difficult. Alternatively, you can purchase a DS12885 IC, a 32KHz crystal and a battery holder and roll your own.

  4. #4

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    I ordered a new ds12887 and a socket for it. Maybe I'll try and modify the old one with a battery holder but right now I just want to get it working again. The only thing that doesn't work when the CMOS is dead is the B drive. I can still play games at least. Having the system running for about an hour restores it for a while at least.

  5. #5
    Join Date
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    I got one off ebay last year for one of my pentium machines and was surprised to see it had a date code that showed it was less than a year old. Fitting it was fairly simple using my desoldering station although without one it would have been a lot more difficult than with a a 2 layer board.
    My efforts turn out to be for nothing though, a couple of weeks ago I powered it up and the onboard voltage regulator fried. I think I'll just drop a 386sx board into the case rather than try to repair the board again.

    Quote Originally Posted by TravisHuckins View Post
    I ordered a new ds12887 and a socket for it. Maybe I'll try and modify the old one with a battery holder but right now I just want to get it working again. The only thing that doesn't work when the CMOS is dead is the B drive. I can still play games at least. Having the system running for about an hour restores it for a while at least.

  6. #6

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    Got a socket put in and put the new ds12887 and it said the memory was reduced... did I get the wrong ds12887? What amount of ram would a Gateway 2000 P5-90 need?

    I just looked at the site where I bought the new one and it said it was 114 byte... do I need the 128 byte one?
    Last edited by TravisHuckins; July 16th, 2017 at 03:00 PM.

  7. #7

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    Now something must really be messed up because I can't get it to post anymore and nothing on the monitor... nothing shows up on the screen... anyone have a service manual for a P5-90 anywhere? The hard drive works in another computer... as I stuck the drive into my 32bit windowd 7 machine and a booted right into MS-DOS.
    Last edited by TravisHuckins; July 16th, 2017 at 05:35 PM.

  8. #8

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    When I was trying to get all the hardware back in the floppy drive fell and hit the heat sink for the processor... could that have broken it?

  9. #9

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    I seriously need some help here... I have no idea what to do...

  10. #10

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    Start by removing everything from the board, and reseating. It's common to knock things loose when you're digging around inside.

    Just had the same thing happen 20 minutes ago on an old Dell I was installing more RAM into. It booted, then crashed, then wouldn't POST.. Reseated the RAM, and it was all good.

    Be sure to use new Thermal paste on the CPU.
    Current Vintage Equipment:
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