Space Invaders - not working - IC temps

mkturtle

New member
Joined
Mar 26, 2012
Messages
3
Reaction score
0
Location
Michigan
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
 
Yes - RAM IC in 'C' position was bad!

After I replaced it, I ran Test ROM fine. Invader fleet sounds and UFO_home did not play, but other than that it was a success!!!

After this I tried booting with freshly burned eeprom's (same type I used for test rom). First few seconds screen was blank, but then shields and invaders starting showing up. Once all invaders were drawn screen went blank????

I think I might have issues now with daughter board. And I think either shifter ICs or board connector is bad. I believe Test ROM does not check data going out to the daughter board? If so, this would make sense?

I pulled eeprom's to double check programming was success and messed around with slot connector pulling boards apart…. Now I have few shields come up and bunch of garbage and screen freezes….

Go figure..
 
Back
Top Bottom