Pacman Sprite Issues

WaterGhoul

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Hi!
I'm having a few issues with one of my Pacman boards that have me a little stumped. I've done some searching but haven't found anything that seems to be close to my issue, but I'm not the greatest at searching forums, so I apologize if this has been asked before.
I have garbled sprites like this image in attractive mode

IMG_1760.jpeg

Once I coin up and press start, the screen looks like this:

IMG_2739.jpeg

Occasionally the maze will disappear and all the characters can move freely around the screen. It also has sound.
I can boot the test ROM in 6E, but I can't read anything because of the distorted letters.

There's also a capacitor that someone added between pin 11 of the LS377 at 4B (the clock pin tied to 6MHz) and pin 7 of 4C. When I disconnected that, it would show the test patterns and then reset at the beginning of the attract screen.
IMG_2748.jpeg

I've replaced all the sockets, RAMS, and all ROMs are freshly burned and verified. I'm also using reproduction sync bus controller and VRAM addresser boards from Mikes Arcade.

Thanks for any help!
 
It sounds like a lot of work has been done on the board. Have you triple checked everything, including your work, looked for cold solder joints, etc.? Have you tried pressing on some of the chips to see if anything changes?
 
Hi!
I'm having a few issues with one of my Pacman boards that have me a little stumped. I've done some searching but haven't found anything that seems to be close to my issue, but I'm not the greatest at searching forums, so I apologize if this has been asked before.
I have garbled sprites like this image in attractive mode

View attachment 823483

Once I coin up and press start, the screen looks like this:

View attachment 823484

Occasionally the maze will disappear and all the characters can move freely around the screen. It also has sound.
I can boot the test ROM in 6E, but I can't read anything because of the distorted letters.

There's also a capacitor that someone added between pin 11 of the LS377 at 4B (the clock pin tied to 6MHz) and pin 7 of 4C. When I disconnected that, it would show the test patterns and then reset at the beginning of the attract screen.
View attachment 823485

I've replaced all the sockets, RAMS, and all ROMs are freshly burned and verified. I'm also using reproduction sync bus controller and VRAM addresser boards from Mikes Arcade.

Thanks for any help!
I'm not a scholar on fixing Pac-Man, but I looked through this page: https://www.mikesarcade.com/arcade/pactrouble.html and the closest symptoms I can find point to the sprite roms at 5E and 5F being at fault.

if your game worked before replacing all the sockets then I would think you maybe blew one of the traces to those roms because it's very easy to do if you used a desolder vacuum tool to remove the old sockets. I discourage going kitchen sink replacing sockets on any Midway games of this era for this reason, and I say this as someone that's very experienced at soldering. like @Shavenyak suggested, you did a lot of work to it. lol
 
I think he said the game was not working before and then he shot gunned all the sockets and roms hoping to find the problem without diagnosing the original problem. His problem now is that the original problem still exists and now he has introduced several more vectors for errors that did not exist before. I would now verify your work that it is not cross connected and that it connects to every other chip in the schematic that touches the sockets you replaced to make sure you are back to the original problem. Hopefully nothing has changed during your first repair attempt
 
I think he said the game was not working before and then he shot gunned all the sockets and roms hoping to find the problem without diagnosing the original problem. His problem now is that the original problem still exists and now he has introduced several more vectors for errors that did not exist before. I would now verify your work that it is not cross connected and that it connects to every other chip in the schematic that touches the sockets you replaced to make sure you are back to the original problem. Hopefully nothing has changed during your first repair attempt
Yes, it came from a lot of cheap damaged boards and had a few missing or damaged sockets, so I just went for it replacing the ROM sockets.
I'm very careful about soldering and replacing stuff, but still learning so all the advice is appreciated!
All of my solder joints look good, and the traces appear intact, but I'll take a closer look with the multimeter when I get home from work.
I also forgot to mention that it used to reset right after Blinky appeared on the attract screen before I replaced the 4A-4D RAM.
Thanks for the suggestions!
 
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