Friend picked up a pole position for $50 -
well, no video sync, but if you tweaked the knobs, you could read RAM 0
so, pulled the boards, replaced the ram chip, plugged it back in, same thing RAM 0 , still no sync.
so, pulled out the Logic Probe starting check the Address Pins on the Ram, dead.. hmm.. checked the schematics, see a Custom 04XX drives the address lines, look on the board, MIA.. , PM Riptor, had chip next day! (USPS must be in turbo mode) pluged it in, wahoo no more ram 0... but now ROM 3... so look at the book, poped out rom 3, checked it against romident website, and what ya know, not found, pulled spare off another board, read it to check to make sure, pluged it in, BooM! we got game bootup, still having sync issues.
moved over to 11B/12B the HSYNC/VSYNC signals were present, and was able to get good picture if used my external sync circuit, long store short, someone had done a "repair" on 11B, and some how connected pin 6 to 12B/9 instead of pin 5??? i have no idea how or why it was that way, but after fixing the botch job of a repair, the sync output was fine, and we have a picture..
http://www.youtube.com/watch?v=5287yyaU2zo
well, no video sync, but if you tweaked the knobs, you could read RAM 0
so, pulled the boards, replaced the ram chip, plugged it back in, same thing RAM 0 , still no sync.
so, pulled out the Logic Probe starting check the Address Pins on the Ram, dead.. hmm.. checked the schematics, see a Custom 04XX drives the address lines, look on the board, MIA.. , PM Riptor, had chip next day! (USPS must be in turbo mode) pluged it in, wahoo no more ram 0... but now ROM 3... so look at the book, poped out rom 3, checked it against romident website, and what ya know, not found, pulled spare off another board, read it to check to make sure, pluged it in, BooM! we got game bootup, still having sync issues.
moved over to 11B/12B the HSYNC/VSYNC signals were present, and was able to get good picture if used my external sync circuit, long store short, someone had done a "repair" on 11B, and some how connected pin 6 to 12B/9 instead of pin 5??? i have no idea how or why it was that way, but after fixing the botch job of a repair, the sync output was fine, and we have a picture..
http://www.youtube.com/watch?v=5287yyaU2zo
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