hi all,
I have Midway SID L shape board set I got from eBay and I trying to bring it back to life. I am at the point where with test ROM I get vertical lines and 'C' in the middle.
I found board was repaired in the past and there was a solder bridge between AD7 and +12V by one of the RAM IC's. That caused damage to the AD7 driver on F6 (9322 pin#12)) which I replaced with 74S157. Result is still the same, vertical lines with C in the middle. When I place new RAM IC over the IC in position 'C', I get same vertical lines now with 'G' in the center.
I think RAM is good but there is something wrong with data lines. I noticed 8216 IC's at B3 and D3 running hot. Could somebody tell me if this is the case in general with this design??? If not I got to find the reason why is it running hot.
The same with 3245 at C5. I replaced it with new IC since it was socket-ed, but it still runs hot. Although, judging by the thick PCB traces, it is probably expected to run hot.
Thanks in advance.
MK
I have Midway SID L shape board set I got from eBay and I trying to bring it back to life. I am at the point where with test ROM I get vertical lines and 'C' in the middle.
I found board was repaired in the past and there was a solder bridge between AD7 and +12V by one of the RAM IC's. That caused damage to the AD7 driver on F6 (9322 pin#12)) which I replaced with 74S157. Result is still the same, vertical lines with C in the middle. When I place new RAM IC over the IC in position 'C', I get same vertical lines now with 'G' in the center.
I think RAM is good but there is something wrong with data lines. I noticed 8216 IC's at B3 and D3 running hot. Could somebody tell me if this is the case in general with this design??? If not I got to find the reason why is it running hot.
The same with 3245 at C5. I replaced it with new IC since it was socket-ed, but it still runs hot. Although, judging by the thick PCB traces, it is probably expected to run hot.
Thanks in advance.
MK