Vertical sync missing SE/30

[bibilit]

I have found a cheap SE/30, cleaned the board, new caps around.

The board got a chime but I have no vertical sync. I have just a bright line in the middle of the screen.

The analog board is not the issue, tested ok. Logic board is the problem.

So far, I have tested the continuity from the connector to both Pals and I have replaced LS166 (was bad anyway) but no improvement.

Any ideas ?

 

[Arbee]

Bright line in the middle isn't lack of sync, it's lack of vertical drive. Gonna be something on the analog board.

 

[bibilit]

No, as said in my post, Analog board was tested ok with another board, issue is in the Logic one.

 

[Bolle]

Bright line in the middle isn't lack of sync

It can be and is very likely if the problem moves over to another known good analog board when logicboard is swapped.
The counters at UG8 and UF8 are responsible for generating horizontal line count and vertical pixel count.
If Vsync is missing then UF8 is likely bad or missing connections somewhere.

 

[bibilit]

Thanks, yes was thinking the same after looking at the schematics.