Pacman dead

bungy

Well-known member
Joined
Aug 24, 2009
Messages
3,055
Reaction score
149
Location
New Jersey
I was tapping into the power transformer and I accidentally shorted the 7volt line. Blew a fuse and replaced it and the game still came up. Went to play it and during gameplay, Pacman turned into Ms Pacman and the sounds were all Ms.Pac. It should be noted that I have souzilla's 4-in-1 kit. I noticed the high score had some strange characters, it read 14044E when it should have been 140440.

I messed with it again the next day and the menu wouldn't even come up, just played some strange sounds and the screen was garbled. Now it just comes up with the screen shown below. Rom chip 5F is hot to the touch.

Any ideas on what I might have done to it?

I have a set of regular Pac-Man roms, but I don't know if I can just swap them in without deconverting the board. Does anyone know if I can use original Pac roms in a board modified for souzilla's 4-in-1 hack?
 
Last edited:
If you shorted the 7v line enough to blew the fuse, that means you most likely pumped quite a bit pf voltage down that line to the board. As it normally converts to 5vdc through some diodes, first check those diodes to see if they are blown. If they converted voltage a lot higher than +5, it's possible you blew some chips, and maybe the kit...
 
Diodes D7 & D8 tested good, I guess that means some nasty voltage got through. I tested the transistor on the heatsink and it's good too. I guess I fried some chips.
 
I guess I fried some chips.

I sure did - by reinstalling the ROMs backwards after pulling them to verify checksums. Got some replacements on the way, but I still want to troubleshoot this thing.
 
I think it probably just corrupted the NVram and a simple reset may have taken care of it. Did you check for good +5vdc on the pcb?
Looking at that screenshot, neither the program rom or character roms are working.

"I have a set of regular Pac-Man roms, but I don't know if I can just swap them in without deconverting the board. Does anyone know if I can use original Pac roms in a board modified for souzilla's 4-in-1 hack?"

It depends on how the mod was installed. I install new sockets and remove the unused pins so there is no chance of them shorting to the pins with jumper wires. Alot of people will bend the eprom legs out and solder the jumpers right to the eprom legs....big mess. On mine you can pull and replace the eprom just like any other eprom. The short answer is probably not. If you had something like two-bits ABC board you could plug that in and bypass the row 6 roms but not row 5.
 
Last edited:
Got the new roms and burned v3.3 of the 4-in-1 kit. Now when it's powered on it looks like the pics and makes some noises. I'm getting 5.1v across C3. I'm guessing it's not a power problem. I also replaced the NVRAM on the high score kit with a 6116 ram for testing and no change.
 
Last edited:
Back
Top Bottom