Re: Pacman Troubleshooting help

On Nov 14, 6:33 pm, James Sweet <jamesswe...@xxxxxxxxxxxxx> wrote:
system...@xxxxxxxxx wrote:
Hey all, I have acquired a Pacman and I have the following problem:

Game will not display video. All I get is a black screen. I am getting
good voltage from the monitor (EH G07) and I have performed some
shotgun repairs to the board just in case.

I replaced all the sockets for the roms and RAM. I also replaced the
sockets on both daughter cards.

I have checked the fuse card on the chassis, and I am getting AC
voltage on all 4 fuses for the logic. The edge connector is in good
shape and making good contact.

I am looking for advice in the right direction from here. I'm sure it
is time to pull out the logic probe.

Thanks for reading.

Does it play blind? IE can you hear game sounds if you hit the coin
switch and press start? If you turn up the Screen knob on the monitor
does the tube glow? Check for 5VDC on the power pins of any of the TTL
chips on the board.

I have display. It locks and just shows a lot of random garbage. I
found an old archive of mowermans site (awesome stuff that should not
be offline) and started with the basics. As of right now I am not
pulsing on my LP when I hit the reset switch and watch the probe pin
15 @ 9c will not change state (stays high) I am starting to wonder if
this 74161 has failed. I will dig a bit deeper to see where the
problem lies. None of the screenshots @ arcade game over match what I
have. I can post a picture if it will help explain the screen.

Side note: When in test mode (coin door switch) the game will make a
few random sounds, garbage will float around on the screen, and then
it will lock. I have not tested the 74161's state during this boot but
I will and I will update the post when I do.

.

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