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1942 Repair Log

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  • 1942 Repair Log

    Symptom: Background graphics corrupted ? tiles are being duplicated vertically in approx. 1 inch rows
    Cure: Pin 11 of LS86 at 10J stuck low (on the lower board) - replaced

    Symptom: board is ?dead?, garbage *briefly* on screen on power on but then screen goes blank. Setting Test Mode on gives a static screen of garbage but won?t run any tests.
    Diagnosis: Checked all EPROMs ? okay. Checked all RAM ? okay. Used a logic probe on the 74LS138 at 10L and found that pin 10 was floating and pins 11, 12 and 13 were all High (should be Pulsing). Tried piggy-backing a 74LS138 onto the same IC at 10L, and the board fired right up.
    Cure: Socketed and replaced 74LS138 at 10L

    Symptom: When board was cold, on power up the ?bar? near the bottom of the screen would sometimes glitch with garbage characters appearing over it. This stopped glitching after a few seconds, and during gameplay there were hardly any noticeable glitches.
    Diagnosis: Determined that the two 2114?s at 9H and 10H on board 2 were responsible for the onscreen sprites, so tried piggy-backing good 2114?s onto them one at a time. Found that the 2114 at 10H was suspect
    Cure: Socketed and replaced 2114 at 10H

    Symptom: Board booting up but won?t coin up, etc and resets when trying to run attract mode
    Cure: Bad 6116/TMM2016 at location A9 ? (chip nearest ROMs) on CPU board

    Symptom: Sprites replaced by random bits of other sprites
    Cure: Bad 2114 RAM at location H10 on video board

    Symptom: Sprites mis-positioned and broken up
    Cure: Bad 2114 RAM at location H9 on video board

    Symptom: No background displayed
    Cure: Bad LS138 at E11 (near edge connector on top board) where pin 14 goes to pin 1 of the Ls377 at location A8 (just below the 6 (or 3) background graphics EPROMs on the lower board

    Symptom: Dotted lines across parts of the screen
    Cure: Bad 2148/6148 at location F2

    Symptom: Boardset powers on and plays okay, all graphics okay BUT random garbage text present in many areas
    Cure: Bad LS367 at location H1 on the CPU board

    Symptom: No sound, just a hiss. No input to sound amp (Capcom original, top board)
    Cure: Bad outputs on LS138 at E9 ? replaced

    Problem: Text corrupting, appearing in the wrong places, etc (Capcom original top board)
    Cure: All outputs on the LS157 at E1 stuck low ? replaced

    Symptom: All sprites extremely blocky and unrecognisable
    Diagnosis: Checked the 6 sprite EPROMs on the lower board and then the chips around them ? found that pin 9 on the four LS194?s was ?dead?. Traced this back to the top board where it was found that all the outputs on the LS74 at location K8 were dead
    Cure: Replaced faulty LS74 at location K8

  • #2
    nice log thanks for sharing.


    • #3
      No problem, I have plenty more, uploading a few now and will upload more when time allows.


      • #4
        Wow, welcome to AA.

        Thank you for adding.


        • #5
          Thanks. No problem. Got a few more yet but they need tidying up.


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