ArcadePosted by Kim Friday, January 16 2009 13:56:53Checked power supply pins polarity and powered the game up.
Games reset over and over again, causing video to flicker with vertical bars.
I have another working PCB of this game, although there are some small differences: one is green and the other one is blue.
The blue PCB has a piggy-back PCB mounted in position 4F with 6 IC's (This should be a sync. bus controller, also used on Pac-Man and Ms. Pac-Man).
The green PCB has a MB14339 IC in the same place (Can't find any info on this!!).
It struck me that the video PCB was connected the wrong way (ribbon cable was connected wrong).
I reversed the video PCB and checked that the power supply was connected right which it was and powered the game up again.
Now I got the 'boot' screen (moving garbage) but game stops after "RAM OK".....!
ArcadePosted by Kim Friday, February 16 2007 10:08:19I powered this game up, and the video was out of sync. Measured the sync signal with a scope and found that it was missing.
Traced
the missing signal back to the AND-gate at T1 (74LS08) and measured the
input signals on pins 4 and 5. They looked fine, but no signal on pin 6.
Desoldered and replaced the part.
Game booted and the picture was in sync.
ArcadePosted by Kim Friday, February 16 2007 10:07:50Powered up the game.
The games boots, but the sprites are going on and off during the intro.
in attract mode, the sprites only move around the upper half of the screen, crossing the maze walls.
Dumped the ROMs and tested them with WINRomIdent and MAME. They all tested ok!
Tested all sync signal 1H-256H and 1V-128V with a video probe (*note 1), all signals looked ok.
Then I tried shorting pins 11, 12, 13 and 14 of U90 and U97 breifly to ground.
If these signals are ok, I should be able to move, change or turn off the sprites.
Something was not right when I shorted pin 11 of U97. Nothing happened when it was shorted to ground.
Changed U97 (74LS161)
Booted the game.
Game fixed and plays.
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(* note 1)
A video probe is a resistor (470R) with one end tied to a video signal (R, G, B), the other end is used as the probe-tip.
This is a tip from "Pac-Man Trouble Shooting Logic Board - Part II" page 30.
ArcadePosted by Kim Friday, February 16 2007 10:07:25Game boots, but there are errors in the sprites.
The errors change when flexing the PCB.
Found a loose connection on a small add-on pcb with 2 x 74LS173.
Resoldered the board and changed the socket.
This
took care of the sprite errors, but when I played the game, later on
when the clouds came, they where missing the center, (only the outline
was visible)
Tried flexing the board again, and the clouds be came visible again, must be some loose connection again.
