Ok so now that my Q*Bert is back together again I need to try and do a few repairs to the board. The first thing I did was make sure the +5 was okay and it's 5.02 measured across a TTL chip on the board. Looks like I'm having a problem with the main board. I guess the first thing I'll ask is should jumper jp12 be jumped or not? I ask because with it jumped the text is legible and the game looks more normal so it would seem that's the case, but I read jp12 isn't supposed to be. Here's a few pics of the background graphics issue....first with jp12 not jumped and then with it jumped. I have brand new mostek ram chips are new, sockets were metered and had continuity and each leg, and finally I verified the background roms were good compared to the MAME set. I'm not sure if the sockets could still be an issue even with continuity checks passing. Any thoughts on this issue? If it comes down to checking the 7400 TTL chips I have a logic probe, but would really appreciate advice on what to look for. Thanks everyone. I know Q*Bert questions get asked often.
Here's 2 screens with JP12 jumped. I will note the 0's on the far right cubes change to 1's as you jump on them....maybe a clue?
Now the same basic screens without JP12...you can see it looks much worse, but from what I read, I thought it wasn't supposed to be jumped.
Edit: Doing some general troubleshooting, I noticed H5 and H6 (SN74S161N) are running considerably warmer than other 74 series chips. I mean we all know something running really warm isn't good so maybe those are related to the problem(s) I'm having. From what I'm reading it looks like those are related to foreground.
Here's 2 screens with JP12 jumped. I will note the 0's on the far right cubes change to 1's as you jump on them....maybe a clue?
Now the same basic screens without JP12...you can see it looks much worse, but from what I read, I thought it wasn't supposed to be jumped.
Edit: Doing some general troubleshooting, I noticed H5 and H6 (SN74S161N) are running considerably warmer than other 74 series chips. I mean we all know something running really warm isn't good so maybe those are related to the problem(s) I'm having. From what I'm reading it looks like those are related to foreground.
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