Problem Sega Hang On no road, only horizontal lines. (Road shifted)

[Georgian2]

Hello,
Here I have another tough one and I can't find anything suspicious. All the ram and rom test good in the test mode.
I understand that the sub CPU is doing all the rendering for the road. Nothing suspicios on the top board. Everywhere I checked there is activity....I don't have the sprites and sound PCBs connected. That part works. The guy who sent this in said at first it faild only half of the road and after a while the whole road. No ideea what that means.
Original Sega 834-5667-01 Hand On REV-A

Here is a video with the issue. From 0:31 one can see the road shifted and small.
Thanks a lot for your input.
https://segaretro.org/images/d/d7/HangOn_Schematics.pdf

 

[Georgian2]

I still haven't found anything faulty on this thing... Nobody has experience with this boards?

 

[Funhouse71]

Had a very similar issue on a Space Harrier, board not quite the same board but similar hardware, ram passed self test but I had corrupted tiles on the scrolling floor, after swapping out a 2016 Toshiba Ram IC51 it ended up being a buffer 74LS245 (IC50).

I think for your revision of the Hang on board I would be concentrating on these locations, page 11 of schematics for the CPU board

 

[Georgian2]

I did change that 2 rams and one of the ls245. None of them were bad. Didn't see any wierdness on the second ls245 so I didn't bother pulling it out. It looks like there is a good signal everywhere on that page from schematics. I'm sure I'm missing something... I'll pull the second ls245 and hope for the best.

 

[xga]

You’re probably already aware of this, but these boards are almost certainly full of Fujitsu logic ICs. I’d start by checking those around the sub-CPU and surrounding area. Given the way Fujitsu ICs typically fail, you’ve got a good chance of pinpointing the bad one by piggybacking. Don’t be surprised if you uncover one failure only to find others as well, pay close attention to even minor changes in behaviour when piggybacking, as they may point to multiple faulty ICs.

 

[Georgian2]

Thanks for your input. I did see this game is loaded with fujitsu ICs. unfortunatly all of them have activity on the outputs. I did piggyback all the ls157 and some other without any results. The fault is stable, so I doubt there are floating outputs, but who knows. I did swap the CPUs around, cables, etc. Roadgfx eprom socket bad maybe? But without that eprom, there are still the horizontal lines present.
Could that two Tile map generators on the bottom PCB be fault? What are they doing there? Since the owner said it first faild half and shortly after the other half...
I'll have to get my oscilloscope on it and see what the signals look like on it.

 

[xga]

It would be handy if you can borrow a working board set from someone and then swap the CPU and Video boards around between them to confirm where the fault is and then focus on that particular board.

Those tile map generator IC's run quite hot however, I think I've only ever seen one fail before, so I would still lean towards a faulty logic IC somewhere.

 

[tb2000]

Yeah I was going to say it's almost certainly one or more logic chips or even iffy ic sockets. I've got a Hang On cab myself, I haven't powered it up for ages but when I did play it last it would come up with an error at startup, turned out to be a socket that one of the chips was in. Can't remember if it was a ram or whatever but reinserting it a couple of times cleared the fault until the next time I switched it on. Never got around to replacing the socket!

 

[Georgian2]

I managed to borow an working hang on set. I swapped the boards around and the problem is on the top board with the CPUs. We'll see this weekend comes next.

 

[Georgian2]

... I spent a few hours on it now and still no trace of any problem yet still broken. I start to lose hope on this one.

4M, 4N, 7F, 7E, 5P, 6P swapped. None of therem were faulty.
5R, 6R swapped. None of them were faulty.
9S swapped, no chage at all.
8N swapped, still no change at all
4S swapped, still the same.

Maybe the CPU Rams at 5 and 6D? But they show no fault on test mode...