Mrs Pac Man goes down all by herself

action53

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When you let go of the stick, she moves down all by herself, all other directions work fine

I confirmed the contacts aren't touching, there's no shorts in the cp harness and the stick goes to center when you let go of it.

Testing between the two wires on each stick the left, right and up has 1.08k ohms when the contacts aren't touching and 0 when they are. Down is the odd man out, 240 ohms when the contacts aren't touching and 0 when they are.


Changed out the LS367 at 8e because that's the one that handles p1 controls according to the schematics, no change. Tested RM8 and all the pins read 1k ohms except for pin 9, it read 240 ohms so I replaced it, still no change. The RM8 I removed tested 1k ohms on all pins out of circuit and the new RM8 that tested good before I put it in tested the same as the old one in circuit

Any ideas?
 

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It was one of those circled caps, C20, all good now.

I did notice a weird twitch on the right side of the maze, when the screen scrolls it follows the part of the maze and whatever part is moving over the right side of the screen doesn't twitch
 

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The only caps I see in the input circuit are circled in the picture, those are caps, right?


Yes, those are caps. If you measure the resistance across the one you pulled out, you'll see it was probably on the order of a few hundred ohms, which means it was bad. This causes the voltage to be pulled down, making the input look like the switch was closed, when it really wasn't. (As the bad cap is closing the circuit, instead of the switch.)


Can't help you on the other issue (as I'm not sure what you're describing), but it looks like your monitor needs a cap kit at the very least.
 
It was one of those circled caps, C20, all good now.

I did notice a weird twitch on the right side of the maze, when the screen scrolls it follows the part of the maze and whatever part is moving over the right side of the screen doesn't twitch

That looks like the good ol' "hum bar". Have you replaced the fuses and fuse bricks? From what I've read many times, that's the first thing you should do. I'm still working on straightening mine out the rest of the way myself. I've replaced my fuse bricks but haven't got around to swapping all the fuses out yet. If I still have a bit of bend then I believe it was the edge connector that needs to be checked out.
 
Yes, those are caps. If you measure the resistance across the one you pulled out, you'll see it was probably on the order of a few hundred ohms, which means it was bad. This causes the voltage to be pulled down, making the input look like the switch was closed, when it really wasn't. (As the bad cap is closing the circuit, instead of the switch.)

Wow, that's crazy. Amazing that you guys caught that.
 
I've already replaced the fuse holders and fuses, new caps and new HOT

It's just the right quarter inch of the maze that wiggles. When I turn the v hold so the screen slowly scrolls the wiggle moves across the screen with the spot on the maze it is now and anything passing over the right quarter inch of the screen looks normal


I'll try to get a video later
 
I've already replaced the fuse holders and fuses, new caps and new HOT

It's just the right quarter inch of the maze that wiggles. When I turn the v hold so the screen slowly scrolls the wiggle moves across the screen with the spot on the maze it is now and anything passing over the right quarter inch of the screen looks normal


I'll try to get a video later

Ah OK. Interested in how it turns out.

"These are our stories. Our Ghost Adventures" hahah
 
She is "Ms Pac-Man", not "Mrs.", so.......

If she wants to go down all by herself, that is none of my business.
 
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