Atari Battlezone vectors skewed?

Shaun KLOV

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Hi. I have a BZ board that was working mostly. I replaced some sockets and it seemed to be working 100% so I let it run on the bench. A few hours later I checked and it was still running in attract mode but the vectors are all over and disjointed.

Now In self test mode with no aux PCB connected I get this:
1000015695.jpg

With the exact same scope settings on a working board set I get this.
1000015697.jpg

I have an FPGA CATBOX so I have done all the vector gen timing tests checked ram and Rom but no errors are found.

When using the CAT box on the failed board and draw a gunsight I get this:
1000015696.jpg
Again with a working PCB with the exact same setting I get a gunsight that looks like this:
1000015698.jpglooking at the pictures above it seems like the X axis is kind of right but the Y axis is drawn shifted really negative and maybe with wrong polarity? Any help would be appreciated. I'm thinking maybe y axis DAC? I probed all the inputs to both DACs and I see no obvious difference with the working and not working PCB.
 
Did you put the game into Self-Test?

This might be a mathbox problem.
 
Do SELF TEST with AUX/Mathbox board disconnected, that will confirm that the AVG board is at fault.
For BZ/RB, you first confirm the AVG(logic) board is working, then add back the MB to confirm it is OK or not.

Here's another good resource for repairs (if you live near a lake):

 
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