Michael Jackson's Moonwalker Sega System 18 graphic glitches

[vsl]

The next case Michael Jackson's Moonwalker Sega System 18 with graphic glitches.
I tested the eprom board on another board and it works normally.
All signals of the memories and ls244, ls245 around 316-5361 are ok.
But I haven't tested the rams.
I would appreciate any advice.

 

[Lurch666]

You need to be posting these in the Tech,maintenance and repairs thread.
This thread is just for completed (or near complete) fixes.
You might get more replies there.

No idea about this PCB as I don't own one but I would suspect counter chips like LS161 or LS166 if this board uses them.
It has a lot of customs so could be one of those and you might not be able to tell.
Also these boards have very thin traces so a damaged trace could be the fault.

 

[vsl]

"You need to be posting these in the Tech,maintenance and repairs thread" i really sorry about this my mistake . Next time i will know .
Yes traces is very very then, board no have physical damages or scratches .

 

[Monstermug]

Is it still on battery?

 

[vsl]

Yes, still on battery.

 

[sukhbir]

I doubt it’s the battery.

As you have put the game in test mode all rams have passed.
ive looked to see on the web to find schematics but no luck.
I guess it’s probably a bad sprite generation custom chip,I’ve not worked on a sega 18 pcb before and I suggest is to reflow all the customs.

Good luck !

 

[Monstermug]

Failing battery on segasystem 32 does some strange things. I cant remember if the moonwalker with milliamps i was repairing had issues in game too. If it hasnt been changed u might want to. i should start keeping repair logs.

Try the sprites ram ic21 ic22 and press down on ic20 customs to see if it changes anything. Also its good practice to check for touching solder legs on this system as there are quite a few that are long enough to bridge.

Most probably the ram. Ram often dont die gracefully and sometimes run in zombie mode.

You can try use a logic probe but a scope would be most helpful testing dying rams. Rams are easy. Read write and enable, data and address , power to it. An oscilloscope should tell u if the signals are good ttl level and within range. Piggy back working ones if they arent already socketed. That how i would approach it.

 

[vsl]

After some time I decided to continue with the restoration. I removed and checked all the chips around the sprite generator but they turned out to be perfectly healthy.

 

[vsl]

I decided to move the ROM board, the encrypted processor, and the Intel chip from Moonwalker to another working board, Shadow Dancer, and this happened?!
working Shadow Dancer :

and the result:

why ? !

 

[Monstermug]

I decided to move the ROM board, the encrypted processor, and the Intel chip from Moonwalker to another working board, Shadow Dancer, and this happened?!
working Shadow Dancer :

and the result:

why ? !

I cant tell if the graphics are glitched or not with that refresh line in the video. Is it working okay or not?

Have you tried pressing down on the custom asics and flexing the pcb a little while its on to see if there are any changes?

 

[vsl]

When the board runs with Shadow Dancer EPROMs, the picture looks perfect. But when I remove the Shadow Dancer EPROMs and replace them with Moonwalker ones, the picture deteriorates — it starts flickering and artifacts appear. All EPROMs have been decrypted, verified, and are in excellent condition. Applying pressure or slightly bending the board makes no difference. In my opinion, the only explanation is that the Moonwalker program uses chips that Shadow Dancer does not, and one of those chips may be faulty. But whether that is truly the case remains a mystery to me.

 

[Monstermug]

To use decrypted roms you have to use a normal 68000 cpu not the encryption fd module i think.

Also have you verified the program roms are good using an eprom burner?

 

[vsl]

To use decrypted roms you have to use a normal 68000 cpu not the encryption fd module i think.

Also have you verified the program roms are good using an eprom burner?

yes ROMs are decrypted,
I am using a normal 68000 processor
ROMs are perfect I have checked them

 

[Monstermug]

Did u replace the whole rom pcb or just swapped the roms? If not u have to make sure the jumpers are set correctly as they may use different eproms configuration

 

[Monstermug]

Btw if you still have the old encryption FD module and the couple of original eproms that you took out to desuicide it and dont need it, i can make use of it?