Time to update this thread Tugce here is the update I promised.
Anyway, I bought this exact game from MaxAsh back in June 2022. For a variety of reasons, I did not have time to set it up until the end of 2023.
When I did get it set up, it was displaying basically the symptoms described in this thread.
One thing to note is that the MPU board had a significant number of socketed chips on it. MaxAsh tells me that he sent this board out and it got returned BEFORE getting fixed. That would account for the socketed chips.
So:
1. I can't completely tell the story of what was wrong because some of those socketed chips might have been part of the issue.
2. When I got the game, however, it was still "watchdogging". You could see this since pin 40 of the CPU was toggling. This is the reset line (active low).
3. The first thing I did was look through all the watchdog related ICs.
4. I thought there might be an issue with the 74LS42 decoders at E4 and H4 (which had been socketed). However, swaping out those chips did nothing.
5. Next, I thought about the counter at M2 (74LS393). Again this was socketed. Swapped and nothing.
6. Finally I also looked at the OR gates at F4 (74LS32). Again no dice.
These were all "easy" checks since they were already socketed and part of the watchdog logic. I had hoped it would be the M2 74LS393 counter since even though the logic probe was toggling, you can't really tell if a counter is counting correctly with a logic probe.
At this point, checked a couple other things.
1. The ROMs. I pulled them. Ah ha! Some of the pins were broken. Burned 3 new 2716s with the code here - https://www.ipdb.org/machine.cgi?id=2454 - naturally this did not fix the watchdogging but would have needed to be done anyway.
2. I pulled the 6800 CPU. It had a resoldered VSS line (pin 1). I figured this was a problem waiting to happen so I replaced the processor. Again, not going to fix the watchdogging but needed to be done.
At this point, I realized, I needed more help. So I burned the test ROM here - https://pinwiki.com/wiki/index.php/Leon_Borre_Atari_Second_Generation_Repair
Of course it was not working but it helped me to diagnose some issues.
The next thing I did was pull and socket N7 and L6. These are 74LS244 chips. They are buffers of the output of the CPU. Replacing these did NOT fix anything. I wasn't hopeful but at this point, I had to start somewhere.
Next I went to the 74LS160 counter at R2 that starts this all going just downstream of the clock. Replaced it. No good.
I pulled F6 (74LS04 inverters) and M1 (74LS74 flip flop) since again, these are some of the last chips not pulled in the watchdog circuit. Still no good.
Finally, I pulled L2 (74LS393). This is the counter "upstream" of the M2 counter I tried earlier. THIS STOPPED the watch dogging.
Bottom Line: Replacing L2 got things to work. BUT I am listing everything else since naturally they could have been part of the issue. Who knows. At least now it is documented.
So at this point it was not watchdogging anymore.
However, it was stuck in test mode and the game lights (other than GI) were out.
I'll post how I fixed this next...