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SE/30 video issue that has ME stumped!

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I think I changed the PAL set already. But I cannot honestly remember. 


You changed the PAL set, was said on one of your earlier post.





As i am lazy, tried to piggyback the PALs first... hoping it will help troubleshooting the board, and worked.

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Yea its been to long. I bought some new ICs for it and I sat it all on the shelf and I havent looked back yet. been way too busy with my standard day job. I cant wait until we get enough capital in where we an hire dev teams and customer service people so I aint gotta do it. ;-)

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  • 2 months later...

Well, if you've swapped every suspect chip on that board, the only things that could be bad are traces... I know that's kind of a stupid suggestion, but I would go bad trace hunting with a schematic if I were you. 


Edited by BadGoldEagle
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  • 9 months later...

Sorry to dig up a dead thread.
Techknight, did you ever find anything on this?  I have precisely the same video bug, but cant seem to figure it out.  Both VRAM's and UE8 have been replaced.  Tested all traces to and from VRAM.  I still get vertical stripes with a slightly abnormal disk icon.  Looks identical to your screenshot.

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  • 2 weeks later...

ISSUE RESOLVED!  Techknight, you may want to add this to your notes.

It appears that Texas Instruments SN74HC166DRG4 is NOT a valid replacement for the the 166 shift register @ UE8.  It causes the discussed artifacts.
I swapped it out again, but this time with a Toshiba 74HC166D, and the issue completely resolved!

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