Working Ms Pacman Screen
Working Ms Pacman Game screen
Vertical pieces of maze scroll across screen from right to left.
2R Pin 11,12,13,14
Fast moving Vertical Lines From top to bottom. Caused by shorting 6 Mhz clock signal.
Chip 3D pin4 or 13
3N pin 9 high
2B shorted to 6MHZ clock signal to pin 14 to pin 9, 10, 11, 12,13,or 15 or 2A short to pin 14 to pad next to it. OR 1E, 2E, short Pin 2 to 1,3,4,5,6,8.
2S pin 11 Sync low
Check 2R, 2S
Chip 2A,2B, 2C, 2D 6MHZ clock signal pin 14 is grounded.
Chip 4B pin 11 short to 3B pin 9-14
6MHZ clock signal short from chip 4B pin 11 to 3B pin 15.
3A bad or missing.
3A Pin 9 short to pin 13.
4R pin 12 short to pin 15.
Problem with 5E ROM
4K, 4N video ram bad
4L video ram bad
4M video RAM bad
Signal from 4A pin 11 to 3A, 3B pin 11 high.
Signal from chip 3B to pin 9 to 7F is high
Signal from 4A pin 12 to 3A, 3B, pin 14 low
Signal from 3B pin 12 to 7F pin 10 too high
3A pin 9 short pin 11, pin 14.
Most likely caused by your monitor. If you have a known good monitor then check green output edge connector 16 is high.
Most likely caused by your monitor. If you have a known good monitor then check red output connector T is high
Most likely caused by your monitor. If you have a known good monitor then check Blue edge connector Pin U is high
5E bad or removed
White Background, Red maze, blocks behind characters.
5A pin 14 high
Pink background, pink maze, red maze outline, blocks behind characters. Yellow behind score and credit.
5A pin 11 high
Chip 3B bad or removed
Blue Box. Black box where characters are. score and credit ok.
A 74157 was placed into socket 3A instead of a 74158.
2C pin 7 short to pin 5,6,8 yellow
3D pin 6 low yellow
2D pin 7 short to pin 5,6, 8 red.
3D pin 3 low red.
2C pin 7 short to pin 1 yellow
2D pin 7 short to pin 1 red
2C short pin 15 to 9 yellow
2D short pin 15 to 9 red
Two bars on screen
2C short pin 15 to pin 10 yellow
2D short pin 15 to pin 10 red.
2C short pin 15 top pin 11 yellow
2D pin 15 short to pin 11 red
2C short pin 15 to pin 12
2D short pin 15 to pin 12 red.
2C pin 15 short to pin 13 yellow
2D pin 15 short to pin 13 red
if 32 bars on screen then 2c pin 7 is short to pin 2 yellow
or 2D pin 7 short to pin 2 red
If 64 Bars then 2C pin 7 is short to pin 3 yellow
or 2D pin 7 is short to pin 3 red.
2C pin 7 is short to pin 3 yellow
2D pin 7 is short to pin 3 red.
2A, 2B, 2C, 2D, pin 1 chip is grounded enabling the chip all the time
All characters are chopped in half with their base on top of their head and stuck on the top row of the game maze under score.
1E or 2E bad or removed
1E pin 15 shorted to pin 16
If characters are flashing then 2E pin 7 and pin 10 are too high
These can be found on 2A, 2B,2C,2D pin 2,3,4,11,12,13 or 1E pins 11,12,13,14, or 2E pin 13,14. 2B is too high, or pin 2,3 or 3,4 or 4,5 shorted. 2A pin 12 & 13 shorted. 2E short pin 7 to p10. 1E 2E pin 15 shorted to 11,12,13,14.
3D bad or removed.
3A, 3B pin 1 low
3B pin 1 short to pin 8.
All characters stuck in lower central corner of screen
1E or 2E pin 9 is too high
All characters look like their being transported. characters become lines from top to bottom of screen still move from left to right.
1E or 2E pin 9 grounded or shorted to pin 15.
1E pin 9 shorted to 11-15
Characters move over the maze lines and act jittery
1E pin 6, 2E pin 2, 3,4,5 or 6 databus Dr3 tru DR7
shorted or high
2B pin 4 short to pin 7
1E or 2E pin 1 short pin 2,3,4,5,8
1E pin 15 short to pin 10
2B pin 3 short to pin 7