Sea Wolf "picket fence" issue

hatrick

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I'm stealing the "picket fence" term from Gorfchampion, since it does a pretty good job of describing this issue. As the mines move across the screen, they leave a "picket fence" of lines (as can be barely seen in my crappy phone photo). The lines stay there and you can shoot them with torpedoes and it acts as if you blew up a mine. You can shoot a hole through the "fence" and hit the ships above, but as a new mine comes by it leaves a new trail of lines.

I'm almost certain the issue is not on the mother board. I've tried two sets of ROMS, and the RAM all seems to test good. The edge connectors have been replaced, so that should not be an issue. The power supply has been rebuilt and puts out the proper voltages. The game coins up, plays, keep score otherwise as normal.

Any idea where to start tracking this down?

And, no laughing at the insane amount of burn on this tube :D

b674f3cf417b4ce7a59275368d0cb94a
 
My sonar pings are not picking up any reflections :D Is there anyone out there? Am I floating in the sea of Sea Wolf repair all alone? Is my Sonar broken?

...SOS...
 
Just to follow up on this for future searches...

On another Sea Wolf board I was working on, it had the "picket fence" issue and the torpedoes would only shoot straight up regardless of where the periscope was aimed.
Turns out that the pin in slot #36 on the 72 pin connector was broken between the pcb and the bottom of the connector. It wasn't visually obvious, but a continuity check of all the pins on the connector found the fault. Fixing that pin solved the "picket fence" issue and allowed for the torpedoes to be aimed when moving the periscope.

I think the "picket fence" issue can be caused by bad bit shifters on the game board, or a bad connection between the mother board and game board.
 
Glad you figured out the problem, and followed up with the diagnosis. Dummies like me can learn from this. I had sent my board out to Yeckley quite some time ago for repairs, and he fixed a ton of different problems. Enjoy your game!!
 
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