oldschool77
Member
Taxi Diplay segments constantly lit AFTER i did an unrelated MPU repair
So I've always noticed the my upper two pops on my Taxi fire slowly compared to the lower pop (they take a second before they are ready to pop again, it's not instantaneous like they should be), and compared to my last taxi. I finally took the time to dig into it, and found those two transistors that have been replaced on my MPU by a previous owner were the wrong value. As you can see from the pics the transistors prior must have burnt up BAD, because the board is just ate up around them....It looks hacky, but i did the cleanest job i could with what i had to work with (The before was WAY worse then my "hack" job, and the jumper was a precaution, the trace looked questionable). I replaced the transistors and drive transistors, did a general inspection of things, and put the board back in the game. Done this a million times on other system11s, never had an issue.
NOW....i have segment "d" (bottom segment on my bottom display) constantly lit all the way across the display at all times, correct brightness, not dim or in and out. I haven't had any display issues ever with this game up 'till now (had it a little over a year now). The BAD thing is, i didn't have my multi meter with me at home this weekend, so all i could really do is check for stray solder that may be shorting,and trace the path from the display back to the CPU....everything looks fine. I'll start tracing back to nite to see if i can find where the ground is.
My question is......i find it hard to believe that this is a huge coincidence that i had no issues, did an unrelated repair, and now have an issue. For the gurus out there, are there any traces around my repair that i could of some how shorted that would be causing this? I looked closely all over, and although it's rough looking, everything appears to be in tact, and no solder overflow...but if i DID overflow and create a ground, where would you recommend i look in my repair areas?? FYI the board has no current or previous Acid damage, everything is clean except around the previously blown transistors. And a new ribbon cable is on order, but I've never seen a ribbon cable turn on an entire row at once. but i guess anything is possible.
Thanks!
Incidentally my top two bumpers are still slow to recover, the proper value transistors made no change, I'll get back to tackling that after i get this display segment issue resolved.
So I've always noticed the my upper two pops on my Taxi fire slowly compared to the lower pop (they take a second before they are ready to pop again, it's not instantaneous like they should be), and compared to my last taxi. I finally took the time to dig into it, and found those two transistors that have been replaced on my MPU by a previous owner were the wrong value. As you can see from the pics the transistors prior must have burnt up BAD, because the board is just ate up around them....It looks hacky, but i did the cleanest job i could with what i had to work with (The before was WAY worse then my "hack" job, and the jumper was a precaution, the trace looked questionable). I replaced the transistors and drive transistors, did a general inspection of things, and put the board back in the game. Done this a million times on other system11s, never had an issue.
NOW....i have segment "d" (bottom segment on my bottom display) constantly lit all the way across the display at all times, correct brightness, not dim or in and out. I haven't had any display issues ever with this game up 'till now (had it a little over a year now). The BAD thing is, i didn't have my multi meter with me at home this weekend, so all i could really do is check for stray solder that may be shorting,and trace the path from the display back to the CPU....everything looks fine. I'll start tracing back to nite to see if i can find where the ground is.
My question is......i find it hard to believe that this is a huge coincidence that i had no issues, did an unrelated repair, and now have an issue. For the gurus out there, are there any traces around my repair that i could of some how shorted that would be causing this? I looked closely all over, and although it's rough looking, everything appears to be in tact, and no solder overflow...but if i DID overflow and create a ground, where would you recommend i look in my repair areas?? FYI the board has no current or previous Acid damage, everything is clean except around the previously blown transistors. And a new ribbon cable is on order, but I've never seen a ribbon cable turn on an entire row at once. but i guess anything is possible.
Thanks!
Incidentally my top two bumpers are still slow to recover, the proper value transistors made no change, I'll get back to tackling that after i get this display segment issue resolved.
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