I,Robot PCB: Incorrect Error Code?

jetusenet

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Hi;
I am troubleshooting an I,Robot PCB set and when fired up, I get a lot of stray, flashing, misc colors and shapes all over the display but you can see the credit=0 display in there.
I placed the game into test and it gives the error:

Bad Ram
C0 2000 W00 R01

Which indicated that the RAM in location 1C/1D on the video PCB is bad. I did many swaps and finally hooked the board to a known working CPU PCB and it worked perfect so the error is not in fact the RAM on the video PCB but originates from the CPU PCB. I also get the error: vp won't stop.

Has anyone else gone through this before?
Thanks
Jeff
 
Do I know any one who knows I robot? I know Jaunup is becoming an expert on I robot. I know if the 12. Something something crystal on the math box section dies you get a screen full of junk.
 
Hi;
I am going to make a clip tomorrow when I get a chance and post it. The screen is not totally garbled. In fact the attract screen is there in it's entirety, it just gets washed out by the flashing of the multicolored polygons and "rays". When I place it in test, it gives me that false RAM error.
Thanks for chiming in.
Jeff
 
OK, here are the links......

This shows the attract screen: http://youtu.be/XhtZHp2sikY
You can see that the attract is playing in the background.

This shows the game being played: http://youtu.be/curp9W8ZlLA

This shows the game in test, displaying a false RAM error code: http://youtu.be/7NwYNrnuG2I
I say false as when I pull the video PCB, where the test states the error lies, and attach it to a known good CPU PCB, it then works 100%.

This shows the vp won't stop error: http://youtu.be/ZPSfwsdvyss

Taking the previous into consideration, I feel that there is something going on, (or not) on the CPU PCB which is causing the RAM error to come up.

Any guidance will be appreciated.
Thanks
Jeff
 
From the limited knowledge in my head about this game. The video screen bank between page of the screen. Video ram error message sound like the decoding section of the video ram might be the issue.

Since you have a working game I would use a scope and see if one of the data pins is missing or stuck down..
 
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