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Thread: IBM 5150(A) motherboard in trouble

  1. #1

    Default IBM 5150(A) motherboard in trouble

    Hi, i have serious problem with early 5150 (first BIOS) motherboard. It appears to be "dead". Let me list some main facts.
    - no beep codes
    - no "speaker crack" on power on
    - with Landmark Supersoft ROM - no video, no beeps
    - motherboard is not shorted, voltages are good
    - first 16k of RAM - TESTED.
    - CPU - TESTED
    - ROM - TESTED
    - BASIC - TESTED
    - 8255 IC - TESTED
    - RN1 - RN3 resistor blocks - TESTED

    Any other ideas?
    IBM PC 5150(A): IBM PC 5150(B): IBM PC 5160 (64-256k): IBM PC 5160 (256-640k): IBM PC 5170 (099): IBM PC 5170 (319/339): IBM PC 5140: IBM PC 5162: IBM PC 5155:
    WANTED! : IBM 5161 Expansion unit, IBM 5175 monitor, IBM 5145 monitor, IBM EGA Graphics Memory Expansion Card, IBM PC screws,
    My IBM PC hardware collection

  2. #2

    Default

    Have you run modem7's Minimum Diagnostic Configuration?
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  3. #3

    Default

    yes indeed
    IBM PC 5150(A): IBM PC 5150(B): IBM PC 5160 (64-256k): IBM PC 5160 (256-640k): IBM PC 5170 (099): IBM PC 5170 (319/339): IBM PC 5140: IBM PC 5162: IBM PC 5155:
    WANTED! : IBM 5161 Expansion unit, IBM 5175 monitor, IBM 5145 monitor, IBM EGA Graphics Memory Expansion Card, IBM PC screws,
    My IBM PC hardware collection

  4. #4

    Default

    What were the results?
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  5. #5

    Default

    dead motherboard?
    IBM PC 5150(A): IBM PC 5150(B): IBM PC 5160 (64-256k): IBM PC 5160 (256-640k): IBM PC 5170 (099): IBM PC 5170 (319/339): IBM PC 5140: IBM PC 5162: IBM PC 5155:
    WANTED! : IBM 5161 Expansion unit, IBM 5175 monitor, IBM 5145 monitor, IBM EGA Graphics Memory Expansion Card, IBM PC screws,
    My IBM PC hardware collection

  6. #6

    Default

    Quote Originally Posted by romanon View Post
    dead motherboard?
    C'mon, that is not one of the results!

    Be specific.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  7. #7

    Default

    results are here

    - no beep codes
    - no "speaker crack" on power on
    - with Landmark Supersoft ROM - no video, no beeps
    - motherboard is not shorted, voltages are good
    - first 16k of RAM - TESTED. (passed on other motherboard)
    - CPU - TESTED (passed on other motherboard)
    - ROM - TESTED (passed on other motherboard)
    - BASIC - TESTED (passed on other motherboard)
    - 8255 IC - TESTED (passed on other motherboard)
    - RN1 - RN3 resistor blocks - TESTED (passed)

    motherboard is still without any traces of life
    IBM PC 5150(A): IBM PC 5150(B): IBM PC 5160 (64-256k): IBM PC 5160 (256-640k): IBM PC 5170 (099): IBM PC 5170 (319/339): IBM PC 5140: IBM PC 5162: IBM PC 5155:
    WANTED! : IBM 5161 Expansion unit, IBM 5175 monitor, IBM 5145 monitor, IBM EGA Graphics Memory Expansion Card, IBM PC screws,
    My IBM PC hardware collection

  8. #8
    Join Date
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    Default

    Time, I think, to get out the scope and check some signals, no?

  9. #9

    Default

    Quote Originally Posted by Chuck(G) View Post
    Time, I think, to get out the scope and check some signals, no?
    probably yes, but this is little bit above my skills. Motherboard is now in skilled hands. I have friend with scope. Some advice, which IC measure first?
    IBM PC 5150(A): IBM PC 5150(B): IBM PC 5160 (64-256k): IBM PC 5160 (256-640k): IBM PC 5170 (099): IBM PC 5170 (319/339): IBM PC 5140: IBM PC 5162: IBM PC 5155:
    WANTED! : IBM 5161 Expansion unit, IBM 5175 monitor, IBM 5145 monitor, IBM EGA Graphics Memory Expansion Card, IBM PC screws,
    My IBM PC hardware collection

  10. #10
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    29,949
    Blog Entries
    20

    Default

    Check to see that the 8088 is getting a proper clock signal and the address lines are twitching to start with.

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