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| SE/30 Problems Part Two |
Posted by: cbmeeks on 2017-10-13 17:10:23
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!
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Posted by: Bolle on 2017-10-14 00:06:43
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.
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Posted by: techknight on 2017-10-14 06:26:12
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.
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Posted by: apm on 2017-10-14 16:05:19
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.
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