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Thread: IBM Parity Memory Card 128Kb Not working

  1. #21
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    Quote Originally Posted by modem7 View Post
    1. Leave RAM chip U50 in.
    Done

    Quote Originally Posted by modem7 View Post
    2. Using multimeter, ensure zero ohms (or very close to that) between pin A09 on card's ISA edge connector and pin 9 of U8 (the actual pin, not the solder side).
    0 Ohms measured

    Quote Originally Posted by modem7 View Post
    3. Using multimeter, ensure zero ohms (or very close to that) between pin 11 of U8 and pin 2 of RAM chip U50 (the actual pins, not the solder side).
    0 Ohms measured

    Quote Originally Posted by modem7 View Post
    4. Using multimeter, ensure zero ohms (or very close to that) between pins 2 and 14 of RAM chip U50 (the actual pins, not the solder side).
    If you mean pin 2 on U8, then I am reading 10Meg Ohms. If you mean pin 2 on RAM chip and 14 on the RAM chip, then yes I am getting 0 ohms.

    So I am thinking the conclusion here is that U8 is the most likely culprit here?

    IBM 5160 - 360k, 1.44Mb Floppies, NEC V20, 8087-3, 45MB MFM Hard Drive, Vega 7 Graphics, IBM 5154 Monitor running MS-DOS 5.00
    IBM PCJr Model 48360 640kb RAM, NEC V20,, jrIDE Side Cart, 360kb Floppy drives running MS-DOS 5.00
    Evergreen Am5x86-133 64Mb Ram, 8gb HDD, SB16 in a modified ATX case running IBM PC-DOS 7.10

  2. #22
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    Quote Originally Posted by lutiana View Post
    So I am thinking the conclusion here is that U8 is the most likely culprit here?
    My money is on U8 too.

  3. #23
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    So I picked up a 512Kb RAM card (the IBM one) and plugged it in, same error message. But am I correct in saying that this card cannot be used to fill the RAM to 640KB? Or are there jumper settings that would allow me to do this?


    The manual shows how to configure the card as the 1st, 2nd, 3rd etc, and the jumpers are set to the 1st card.

    On another note, I managed to find what I think is an Enhanced Memory Expansion Adapter, which should arrive this weekend. Not sure how much RAM on that card, but time will tell.

    IBM 5160 - 360k, 1.44Mb Floppies, NEC V20, 8087-3, 45MB MFM Hard Drive, Vega 7 Graphics, IBM 5154 Monitor running MS-DOS 5.00
    IBM PCJr Model 48360 640kb RAM, NEC V20,, jrIDE Side Cart, 360kb Floppy drives running MS-DOS 5.00
    Evergreen Am5x86-133 64Mb Ram, 8gb HDD, SB16 in a modified ATX case running IBM PC-DOS 7.10

  4. #24

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    Correct.

  5. #25
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    Quote Originally Posted by lutiana View Post
    So I picked up a 512Kb RAM card (the IBM one) and plugged it in, same error message. But am I correct in saying that this card cannot be used to fill the RAM to 640KB? Or are there jumper settings that would allow me to do this?
    Quote Originally Posted by bear View Post
    Correct.
    "What bear said."

    Extended memory only.
    '1st' setting = 1M to 1.5M
    '2nd' setting = 1.5M to 2M
    '3rd' setting = 2M to 2.5M
    '4th' setting = 2.5M to 3M
    '5th' setting = 3M to 3.5M

  6. #26
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    Okay, replaced U8, painstakingly checked that each solder joint was continuous with some part of the trace coming off of it, so I can say that all there are no dry solder joints and there is continuity from the pin all the way to the board and down the traces.

    That said, I am still getting the same error.

    Any suggestions on where to go from here? Could it be some sort of clash with the video card (~512Kb Cirrus Logic GD5420 VGA card)? Bios issue?

    IBM 5160 - 360k, 1.44Mb Floppies, NEC V20, 8087-3, 45MB MFM Hard Drive, Vega 7 Graphics, IBM 5154 Monitor running MS-DOS 5.00
    IBM PCJr Model 48360 640kb RAM, NEC V20,, jrIDE Side Cart, 360kb Floppy drives running MS-DOS 5.00
    Evergreen Am5x86-133 64Mb Ram, 8gb HDD, SB16 in a modified ATX case running IBM PC-DOS 7.10

  7. #27
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    Quote Originally Posted by lutiana View Post
    Okay, replaced U8, painstakingly checked that each solder joint was continuous with some part of the trace coming off of it, so I can say that all there are no dry solder joints and there is continuity from the pin all the way to the board and down the traces.
    Back to socket U50. Apart from the DATA IN (pin 2) and DATA OUT (pin 14) pins, all the other pins are tied to the same pin on the other RAM chips (pin 1 to pin 1, pin 3 to pin 3, etc.). Do those other pins have continuity to the same pin on say, U51 ?

    Quote Originally Posted by lutiana View Post
    Could it be some sort of clash with the video card (~512Kb Cirrus Logic GD5420 VGA card)?
    I think it very unlikely, but I have been surprised so many times.
    Pity that you do not have another make/model of card to try.

    Quote Originally Posted by lutiana View Post
    Bios issue?
    Again, very unlikely. If your 5170 motherboard has its original IBM BIOS, then I know that the card works in the 6 MHz 5170 with 01/10/84 revision BIOS, and 8 MHz 5170 with 11/15/85 revision BIOS.

    Quote Originally Posted by lutiana View Post
    Any suggestions on where to go from here?
    Back at post #16, you wrote that you swapped the bit 0 chip with the bit 15 chip. Are you certain they got swapped? Didn't get distracted mid course?

    Earlier, I observed that multi-bit failure was sometimes reported as single-bit failure. So try swapping other chips (besides bit 15) into the U50 socket. I am pretty sure that you have already tried that.

    Do you have a logic state analyser? What about a logic probe ?

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