Ms. PacMan Problem (pics)

[jeff412]

I went back and checked my solder joints for shorts. There is actually a small trace on the board that is very close to the pins. Most of the coating was gone so the solder flowed to it as well. That shorted about 5 pins together. I resoldered everything (being a little more careful this time) and now I have a single blinking "O" on a black background.

Jeff

 

[Riptor]

Throw the test switch on and see if it comes up with anything. I doubt it will but its something thats easy to try.
Check all the 2114 rams. Pull them and reseat then retest. Sounds like you might still have issues there where you changed the socket out. You started with a somewhat working board.

 

[jeff412]

I disconnected the daughter card and put a Z80 in. The game comes up and plays without mazes. I haven't done anything to the daughter card except reseat the chips on it. What do you think?

Jeff

 

[Riptor]

No maze, are characters there?
Can you see the dots?

 

[jeff412]

Yes, the characters are there and I can see the dots. However, when Ms. PacMan eats the dots, she faces down.

Jeff

 

[jeff412]

Throw the test switch on and see if it comes up with anything. I doubt it will but its something thats easy to try.
Check all the 2114 rams. Pull them and reseat then retest. Sounds like you might still have issues there where you changed the socket out. You started with a somewhat working board.

I don't have the test switch hooked up. It's all sprawled out on my test bench.

Jeff

 

[HudsonArcade]

I went back and checked my solder joints for shorts. There is actually a small trace on the board that is very close to the pins. Most of the coating was gone so the solder flowed to it as well. That shorted about 5 pins together. I resoldered everything (being a little more careful this time) and now I have a single blinking "O" on a black background.

Sounds like a bad RAM 0 and a reset.... more shorted traces, prob.

 

[HudsonArcade]

Throw the test switch on and see if it comes up with anything.

Pacman runs self-test on boot regardless of whether the test switch is on. the test switch just makes it stop at the end of test instead of either going into game more or rebooting.

 

[jeff412]

Sounds like a bad RAM 0

where is this located?

and a reset....

What do you mean?


Jeff

 

[Riptor]

Ram 0 is the 4K 2114 I believe.

"Yes, the characters are there and I can see the dots. However, when Ms. PacMan eats the dots, she faces down."
The mspac facing the wrong way is because your basically running pac with mspac character roms by not having the aux board installed.

 

[jeff412]

The mspac facing the wrong way is because your basically running pac with mspac character roms by not having the aux board installed.

That's what I assumed as well. Do you think it's a ram issue since it plays without the daughter board?

 

[Riptor]

No, I think thats a whole different issue. Likely a flakey ribbon cable or socket. Forget about that aux board for now until you get the main board working right.

Did you inspect the back of the board for pins that may be bent over and shorting? You need to look the board over real good.

 

[jeff412]

So without the daughter board, what should I see when it plays. All that I've seen anywhere is that it plays as pac-man. What does that mean?

Jeff

 

[jeff412]

Did you inspect the back of the board for pins that may be bent over and shorting? You need to look the board over real good.

I'll check it closer tonight after work.

Jeff

 

[Riptor]

So without the daughter board, what should I see when it plays. All that I've seen anywhere is that it plays as pac-man. What does that mean?

Jeff

With the mspac character roms and no aux board it will play pacman game with a messed up pac.

 

[jeff412]

I looked it over at lunch and I found a couple of bent pins, but nothing obviously touching. I fixed those. I removed and reseated all of the 2114's. It still has no maze. If you complete a level, the maze outline will flash. Where is the maze stored?

Jeff

 

[jeff412]

Got it! The reason there wasn't a pac-man maze is because the blue was turned all the way down on the monitor. I reseated the roms on the aux board and everything fired up and ran. Woo Hoo! Now the hard part. I have to get it into the cabinet. I don't have the right monitor. I have a K4900 which is a vertical mount, but ms pac uses a horizontal mount.

Jeff

 

[Riptor]

Good job. Thats the nice thing about being able to bench test stuff. I know my bench monitor is good to go so it takes that out of the equation.

 

[Scucci]

Good job. Thats the nice thing about being able to bench test stuff. I know my bench monitor is good to go so it takes that out of the equation.

You're telling me... I've been meaning to build a test rig for a long time... but I'm oddly too lazy to build the rig, but not so lazy as to not wanting to carry my monitor and harness around from machine to machine to test things... It's a delicate balance.

But, glad he got the board/monitor issues figured out.

 

[Riptor]

I work on so many pac boards that I just built a dedicated test station just for the pacs. With a jamma adapter you can run into odd power problems that might not show up until you hook it up to a real cab.
If you do any amount of board work its worth the time to go ahead and make a test station. I built an iso into my jamma rig so I can also test monitors with it.