pacman cocktail - sprite issue?

[pimppride]

a pacman cocktail made its way into my house over the holidays, while it arrived DOA I was able to get it going with a little cleaning, but the sprites are messed, where would I get the new roms for this? or is this bad ram/rom ?

thanks in advance   

[iankellogg]

Pull the sprite eproms out (5E and 5F) and make sure no pins are bent or broken. If all is well then I would suspect a bad address buffer IC. I doubt the eprom is bad.

[pimppride]

ill check that out and see what I get, thanks 

[pimppride]

the eproms are very dirty and look overheated on this board ( dark brown and purple coloring on the legs )

when I removed 5E and 5F , pin 1 was broke on 5F and part of the pin stayed in the socket

I cleaned them and ran a jumper wire from pin 1 to the other side of the board socket, with no change in the picture

thinking i'm going to clean the other set of eproms as it can't hurt.. .





 

[iankellogg]

those are the old proms. i would consider replacing them with eproms. As far as the other eproms (6e-6j) I wouldn't touch them. if the game isn't crashing then they are fine. Most likely you will break the legs off when you remove them too.
Not sure where that jumper wire is going but i am still going to bet that the broken eprom is your problem. Pin 1 is A10.

[HarrieD]

Buy an eprom reader from ali express. Those things cost 33 dollars and can be a huge help troubleshooting these kind of issues. If you find the proms to be okay you can search for an alternative cause of your problem. While you're at it buy a logic probe.

Then watch the episodes of onecircuit's repair on pcb repairs, and to 101 logic episode. There you will find all the info you need.

Ian is correct, the program is running so leave those proms be where they are. I think one adress line is pulled to 1 or 0. What you see on the screen is that each sprite is displayed twice, half of the sprite. Like the MSB (most significant bit) is tight to either 0 or 1. This tells me the sprite roms are okay, but the addressing is causing the issue.

Good luck man!

[HarrieD]

Another tip to check the roms: put them in an eprom reader and feed the roms to mame. If you got the same issue in mame you know that rom is bad.

[HarrieD]

When character rom 5e is removed game plays but maze is missing
When character rom 5f is removed game plays but pacman and ghost monsters are blocks of color.

Because of the fact that both the maze and pac are fucked up i guess the addressing is wrong on both proms. Get a logic probe en check all address and data lines on 5e and 5f. Is a line stuck on 0 or 1 or maybe floating?
Another thing to try: remove 5e, is PAC and his friends okay now? Reseat 5e, remove 5f, is the maze okay now?

[pimppride]

well good news is I was able to fix it with the original proms.. .

after ordering new eproms from twisty wrist online, I decided to mess with this some more, cleaning the other 4 proms and custom chip, I found a cracked leg on the custom chip.. . ran another jumper wire for that broken pin an now it works great. ..

now I have some new eproms in the mail for backups

thanks again for the help and suggestions

[iankellogg]

which custom chip? There isn't that many 'custom' chips on Pacman...

[pimppride]

the one right next to the z80 cpu

[pimppride]

to be more specific for anyone with similar issue in the future, the 2nd broken leg was found on chip 6D at the 7th pin down from the top left