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Robocop Repair Log

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  • Robocop Repair Log

    Symptom: @ symbols all over the display, sometimes only on a portion of it ? background graphics and sprites just about visible behind the @ symbols
    Diagnosis: Determined that the text generation was at fault, as disabling the text (lift pin 8 of the 7425 at location 14E on the CPU board) causes the @ symbols to vanish and all graphics to be visible, but of course no text is then displayed either. The 27512 mask ROMs (EP22 and EP23) are responsible for the text, etc yet these were fine. Finally found that the DAC-06 surface mounted custom at location 3A had a bad output on pin 122 (I think, schems may be wrong ? to find, look at the CPU board with the edge connector to the right, find the large custom at 3A, look to the left of it, see the PTH?s to the left, count those from the bottom, seventh UP is the pin) which connects to pin 18 of the TMM2063 at location 12A ? or rather, it should but it didn?t, there was a break in the track between those two pins. Fixed the break and so fixed the fault.
    Cure: See Diagnosis

    PROM Info

    MB7122E (EN-24) PROM at 17E on CPU board ? Removing this causes all text to disappear along with the sprites and the foreground layer of the background graphics to be absent (but the background layer is still visible)

    MB7116E at 12C on CPU board ? Removing this causes all sprites to disappear

    MB7124E at 12A on ROM Board (although the board is screened as MB7130) ? Removing this causes the display to disappear, although coining up makes the correct text appear (and sound to play), intro graphics appear on starting a game, then nothing, it won?t even play blind (although the coin up sound still plays on coin insert)

    (note: dumped the two PROMs missing from MAMe (17E and 12C) and submitted them to the MAME team (Aaron Giles) on 10th May 2009)

    PAL Info

    PAL16L8BCN at 9A on the ROM Board ? removing this appears to have the same effect as removing the MB7130 PROM at 12A
    Last edited by VectorGlow; 11th May 2009, 02:00 AM.
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