mcandrewsoun
Well-known member
I had a BW board that I had almost given up on, and had reached out to some folks for repair, and had mentioned that theres not a lot of vector board info.. So I thought Id share..
The symptoms were, partial collapse on the Y axis. Most of the positive axis was fine, but the negative was mostly collapsed. Test mode showed a pecular dip on the big box, and the cross hatch and color bars were totally hosed. The BW would crash after coining up,starting, when the web came up.
heres the test screen:
http://www.flickr.com/photos/mcandrewsnd/8080840523/
Heres what I did:
1. Tested Roms in the Gravitar board, they tested fine.
2. Tested Gravitar Roms in BW board, same issue, except game didnt crash.
3. Replaced TL082 and DAC on Y axis.
4. Replaced RAM.
5. Did signature analysis on the vector section, all sigs were fine.
6. Linear Scaler was fine.
I tried one last thing. I was convinced the problem was in the analog section, and I thought maybe the centering/invert switch was leaky.. So I swapped it, and sure enough, it came up correct.. As a side note, somehow I killed the linear scaler DAC.. but swapping that fixed the issue.. What is really confusing, is how the switch chip caused the BW vector engine to crash..
Anyway, thought Id put the info out there in case someone else has a similar issue..
Andrew
The symptoms were, partial collapse on the Y axis. Most of the positive axis was fine, but the negative was mostly collapsed. Test mode showed a pecular dip on the big box, and the cross hatch and color bars were totally hosed. The BW would crash after coining up,starting, when the web came up.
heres the test screen:
http://www.flickr.com/photos/mcandrewsnd/8080840523/
Heres what I did:
1. Tested Roms in the Gravitar board, they tested fine.
2. Tested Gravitar Roms in BW board, same issue, except game didnt crash.
3. Replaced TL082 and DAC on Y axis.
4. Replaced RAM.
5. Did signature analysis on the vector section, all sigs were fine.
6. Linear Scaler was fine.
I tried one last thing. I was convinced the problem was in the analog section, and I thought maybe the centering/invert switch was leaky.. So I swapped it, and sure enough, it came up correct.. As a side note, somehow I killed the linear scaler DAC.. but swapping that fixed the issue.. What is really confusing, is how the switch chip caused the BW vector engine to crash..
Anyway, thought Id put the info out there in case someone else has a similar issue..
Andrew