SE/30 Problems Part Two

[cbmeeks]

When I boot my SE/30, I get a screen with horizontal stripes.  Nothing else.  No beeps, either.

First thing I did was recap the logic board.  I believe I did a good job but I can double check (even though I've triple checked already).

Tonight I replaced UE8 (74LS166) with a new one.  Actually, I only had 74HC166 but I think that should work.

After I replaced UE8, I still get the exact same thing.  Nothing changed.

Any ideas?

Thanks!

 

[Bolle]

Check out all the traces in the video circuit according to the schematic.

Also the other 74 series ICs in the same row as UE8 can go bad as well. I usually desolder them all to test them in an IC tester. Having them desoldered also makes cleaning up the cap goo below them easier.

 

[techknight]

if your not getting a chime either, the problem is further upstream. Get out of the video circuit and start looking at RAM/ROM traces, and GLU traces. 

 

[apm]

Check UB11 too (Sony sound chip) which for obscure reasons controls the reset line. If the CPU is held in reset (pin 5 on UB11 low) you'll get the result you see. Of course a dozen other things could be causing it as well.