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Irem UNDERCOVER COPS Graphic issue [ HELP ]

TheCrow

TheCrow

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Hi everyone,
I got this undercover cops pcb in pretty good condition , but it has some graphic issues, only the characters are effected , the background looks really nice
D79DCC97-CCB4-4DB7-95B2-1DB2ECF7914F.jpeg
E33AB6E3-363C-4D1A-9BD1-98F16B252127.jpeg


The EPROMs are already cleaned , if anyone can help it would be much appreciated.
Thank you all.
 
jassin000 said:
Did you dump them and compare with MAME set?
Could be corruption/data rot.
Click to expand...
thank you for replying, i had that idea but the problem is I don’t have a good programmer so I can’t dump them and I don’t know what the mask Roms reference are.
 
Maybe some of the gfx roms are in the wrong order? Post a pic of the rom board, i think some of the labels were wrong in the mame src for a while. Could have been a misplacement of roms.
 
Asure said:
Maybe some of the gfx roms are in the wrong order? Post a pic of the rom board, i think some of the labels were wrong in the mame src for a while. Could have been a misplacement of roms.
Click to expand...
Idk if they are miss placed 🤷‍♂️ I got it like this
 

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Try detaching the two boards and reattaching them again. The connectors may be making poor contact. Doing it a few times may help restore the connection.
 
OK, the four ROMs responsible for sprite data are C0, C1, C2 and C3. The components installed into those sockets in your pic are all identical NEC D23C4001EACZ chips, so we can't tell from the labeling if they are each installed in the correct socket.

I think it's likely that each chip is in the right socket, but that one chip has become corrupted. If you have access to a EPROM programmer, you can dump each chip as a 27C4001 EPROM and compare the dump against MAME to see if it matches. When you find a chip where the dump doesn't match, you can program a fresh 27C4001 or 27C040 EPROM with the MAME file for that chip and install it in the appropriate socket.

The current MAME files for each chip are:
C0 = uc_k16m.rom
C1 = uc_k17m.rom
C2 = uc_k18m.rom
C3 = uc_k19m.rom

Older versions of MAME used different file names:
C0 = uc_c0.ic26
C1 = uc_c1.ic25
C2 = uc_c2.ic24
C3 = uc_c3.ic23
 
ShootTheCore said:
OK, the four ROMs responsible for sprite data are C0, C1, C2 and C3. The components installed into those sockets in your pic are all identical NEC D23C4001EACZ chips, so we can't tell from the labeling if they are each installed in the correct socket.

I think it's likely that each chip is in the right socket, but that one chip has become corrupted. If you have access to a EPROM programmer, you can dump each chip as a 27C4001 EPROM and compare the dump against MAME to see if it matches. When you find a chip where the dump doesn't match, you can program a fresh 27C4001 or 27C040 EPROM with the MAME file for that chip and install it in the appropriate socket.

The current MAME files for each chip are:
C0 = uc_k16m.rom
C1 = uc_k17m.rom
C2 = uc_k18m.rom
C3 = uc_k19m.rom

Older versions of MAME used different file names:
C0 = uc_c0.ic26
C1 = uc_c1.ic25
C2 = uc_c2.ic24
C3 = uc_c3.ic23
Click to expand...
Hey , thank you so much for the detailed explanation, I have a mini pro cs programmer and it supports reading only 27c040 eeprom can i read them as 27c040 ?
Thank you 🙏
 
Since you have a programmer, try swapping the chips out out with programmed 27C040 or 27C4001 EPROMs anyway. It is rare, but it is possible for a chip to read out on a programmer properly (since the reading is done sequentially) and not operate correctly on the game PCB (since the game reads each ROM pseudo-randomly). I’ve had it happen myself at least once.

Otherwise, I suggest purchasing an inexpensive logic probe and start probing the lines on the four EPROMs for a stuck Address or Data line. I made a tutorial video that covers the process with a Fire Shark board - the same procedure applies here.

View: https://youtu.be/2PAtTIAijeA
 
There's a big chip in the corner of the bottom board. Try pressing it down with the game running. If there are changes to how the sprites look it may be the case that it has cold solder joints. That would explain the issue and could be addressed by reflowing it. If that doesn't work, it may have gone bad for good. It's a custom chip so you'd need a donor board to replace it.
 
Oh, there's a couple of RAM chips that IIRC are connected to that chip too. If they've gone bad that could also potentially explain the issue.
Get the logic probe in any case, it's a must have tool for troubleshooting.
Good luck!
 
I have had a similar issue where I lost all of the sprite layer from my In The Hunt, check the jumper at J3 which is very near to the edge of the pcb and can become loose or get knocked.
After replacing mine all sprites returned .

Edit: mine was a very loose fit, so I gently pushed the pins apart the smallest amount to make the jumper a more secure fit.
Notes_220701_173239_efd.jpg
 
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