Wonder Boy in Monster Land

[r67055]

Hello. I'm a little stuck. There is a graphic error on the pcb. first of all i read the contents of all eproms. All eproms match the mame database. After removing eproms E4, E5 E6 E7, the moving characters disappeared from the screen. I thought that the associated RAMs might be the fault. I took them out and put them in the socket, but unfortunately the RAMs are not bad. Where else can I look for an error?
Thanks

 

[r67055]

Pics

 

[MagicianLord77]

Hi, those RAMs you replaced might be work rams, if you turn on the game w/o them, does it boot up?.
If those ROMs are good, and you're sure they're related to the failing sprites, with a multimeter you could check what's the destination of their data lines, they could go to a failing logic IC buffer/flipflop/etc. Found on some Wonderboy repair logs over the internet that horizontal lines on sprites are usually related to failing 74LS157s, but the bootleg could be different. A logic probe could come in handy to troubleshoot it

 

[r67055]

Hi, those RAMs you replaced might be work rams, if you turn on the game w/o them, does it boot up?.
If those ROMs are good, and you're sure they're related to the failing sprites, with a multimeter you could check what's the destination of their data lines, they could go to a failing logic IC buffer/flipflop/etc. Found on some Wonderboy repair logs over the internet that horizontal lines on sprites are usually related to failing 74LS157s, but the bootleg could be different. A logic probe could come in handy to troubleshoot it

Thank you very much for your reply.
If I take out the RAMs, the moving characters disappear. I sent a picture.
I have a logic probe. Unfortunately, I don't know what to see on which ttl pin? I checked the data lines between the EPROMs and the RAM, there is no broken line.

 

[r67055]

there are 157 in the area

 

[MagicianLord77]

Here are Sega Star Jacker schematics that I've seen others use to repair Wonderboy: https://drive.google.com/file/d/1AYv91Pfp4V8LqV062SefD2vPYrT73zQM/view
About the 74LS157s, the usual thing to check is for stuck/nc outputs (pins 4, 7, 9, 12): https://eater.net/datasheets/74ls157.pdf. If you found a stuck one, it would be good to then check if there are inputs, and so on.
Another thing to try, a bit unsafe, is to just piggyback a good 74LS157 (or whatever logic IC, also RAMs too) on top of the ones you believe could be bad and see what happens. If done wrong could create more issues than solutions! (short circuit)
Bootlegs are difficult

 

[r67055]

Here are Sega Star Jacker schematics that I've seen others use to repair Wonderboy: https://drive.google.com/file/d/1AYv91Pfp4V8LqV062SefD2vPYrT73zQM/view
About the 74LS157s, the usual thing to check is for stuck/nc outputs (pins 4, 7, 9, 12): https://eater.net/datasheets/74ls157.pdf. If you found a stuck one, it would be good to then check if there are inputs, and so on.
Another thing to try, a bit unsafe, is to just piggyback a good 74LS157 (or whatever logic IC, also RAMs too) on top of the ones you believe could be bad and see what happens. If done wrong could create more issues than solutions! (short circuit)
Bootlegs are difficult

thank you very much for your help. I'm happy.
I looked at the schematic. I saw that the RAMs to which the 74ls157 are connected are elsewhere. I decided to check the RAMs. one of the 4 was faulty.

 

[r67055]

Thank you very much for your help!

 

[r67055]

The R type pcb also has a graphic error. Could this also be a RAM error?

View: https://youtu.be/Y3xMVlLEL2c?si=HOXizSckar-DiT5p

 

[Monstermug]

Do u have another m72 pcb? Swap boards around to narrow which board has the fault. Most probably middle pcb sprites ram or rom. The nanao customs are very prone to failure also the ram. Its almost always the middle pcb on the m72s ive fixed.