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Thread: Help tracking down a very intermittant memory failure on my IBM EGA

  1. #11
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    Answered by own question by looking at your pictures At least you should know which chips are the likely suspects.

  2. #12
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    Quote Originally Posted by maxtherabbit View Post
    Looks like my memory tester will be getting a workout when it arrives.
    What was the exact make and model of this?
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  3. #13

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    Quote Originally Posted by Trixter View Post
    What was the exact make and model of this?
    CHROMA ATE INC. Model 3201A

  4. Default

    Is it always the same addresses?

  5. #15

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    Quote Originally Posted by EkriirkE View Post
    Is it always the same addresses?
    the two screenshots attached to the OP are two different instances of the test failing, so I'd say no but same range

  6. #16

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    ok new information - I was able to reproduce an instance of the original error with the daughterboard removed so the problem is indeed on the card itself.

    I also discovered a sure fire way to produce an error - running PCDOS DEFRAG will give text mode corruption 100% of the time on this specific EGA, with or without the daughterboard. Swapping it with another IBM EGA makes DEFRAG run fine.

    BTW (the memory tester only supports 64kx1, 64kx4, 256kx1, 256kx4, 1Mx1, 1Mx4 and 4Mx1 DIPs - no ability to test 16kx4 or 16kx1)

  7. #17
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    You might be able to discover the errant chip via piggybacking before you have to get out the desoldering braid.
    Offering a bounty for:
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  8. #18

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    Quote Originally Posted by Trixter View Post
    You might be able to discover the errant chip via piggybacking before you have to get out the desoldering braid.
    eh I 'll consider it. I have a big boy vac desoldering pump so removing them isn't the end of the world

  9. #19

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    I've now replaced U1 U2 U50 and U51. These all could correspond to bits 6,7. No effect on the text corruption in DEFRAG. I'm probably going to try replacing the other half of the memory chips, but I'm seriously beginning to consider a logic problem on this EGA.

  10. #20

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    annnnd replacing U10 fixed it... WTF over

    so should I just replace the last 3 DIPs since I'm almost there and the results seem to indicate a possible multiple failure? or just leave U10 and revert the other changes?

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