Popeye Graphic Issue with Video

joeybagadonuts

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Donor 10 years: 2012-2021
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Just picked this up from Lyons Arcade (Thanks Ron, board as described). I confirmed it is the video board because the CPU board works great with my working set. I replaced all socketed chips with the same results. I have a Logic Probe but have no idea how to use it. Im eventually going to compare the two boards with the probe and see if there are different readings. In the meantime do you guys suggest looking at something specific? Thanks

 
Subscribed. Im in the same exact boat, with slightly different graphic glitches than you have, but isolated to the video board, and also swapped all chips from a working board with same results.

My plan of attack is to pull the monitor and power supply out and make a little bench setup.

Then I'm going to load the good board to the bench, and run the probe on every pin of every rom first, noting high/low/pulsing. Then compare with the bad board. If I find any differences, I will then trace back through the schematics to the chips that feed the roms, looking for one that has a stuck input or output pin that is different from the working board.
 
I suspect a problem with the upper four bits of the video address bus (DDT4-7). Related components are 4U (LS367), 5R (2114) and 5N (2716/2732).
 
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I suspect a problem with the upper four bits of the video address bus (DDT4-7). Related components are 4U (LS367), 5R (2114) and 5N (2716/2732).

Thanks Phil. The 5n was tested and checked out good. I'll compare the 4u and 5r with my working board. I actually might have spares.
 
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Piggyback test FTW !!!!

Awesome you got it working. Now learn read schematics and you're set!
 
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