Dokert
Well-known member
The monitor that I am using on my test bench is a 4900, but in this case it really doesn't matter.
I was testing an unknown condition Centipede CT with a blown 8-liner monitor. Connecting the game up to my 4900 test bench monitor gave me garbage on the screen. Using my UR with the game board out of the CT I get a solid blue screen. Using my known good board in the CT I have garbage on my test bench 4900.
Wire chasing revealed that the R and Ground had been swapped, as well as the blue and green. Moved the wires to their correct locations and now I have a badly out of sync picture. Back to chasing the wires again, and the monitor inputs are wired for positive individual sync. (correct for a Centipede UR) The video edge connector P19 (IIRC) is wired for composite negative sync. (correct for a Centipede CT)
Changed the monitor input to composite negative sync and the picture came up beautiful.
This game came to me in unknown condition, and it was obvious to me that someone tried to fix the video issue at some point in time. Most likely they were using the scat for an UR instead of a CT.
I was testing an unknown condition Centipede CT with a blown 8-liner monitor. Connecting the game up to my 4900 test bench monitor gave me garbage on the screen. Using my UR with the game board out of the CT I get a solid blue screen. Using my known good board in the CT I have garbage on my test bench 4900.
Wire chasing revealed that the R and Ground had been swapped, as well as the blue and green. Moved the wires to their correct locations and now I have a badly out of sync picture. Back to chasing the wires again, and the monitor inputs are wired for positive individual sync. (correct for a Centipede UR) The video edge connector P19 (IIRC) is wired for composite negative sync. (correct for a Centipede CT)
Changed the monitor input to composite negative sync and the picture came up beautiful.
This game came to me in unknown condition, and it was obvious to me that someone tried to fix the video issue at some point in time. Most likely they were using the scat for an UR instead of a CT.





