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techknight

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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@techknight

 

The SE/30 has two different sets (revisions) of PALs... i was lucky as apparently the one i changed is common in the two revisions.

 

For troubleshooting purposes, can i use one set instead of the other ?

 

 

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Even the ones from the early board revision that has the patch wire installed?

Or does that wire make the routing the same as on the later boards?

Never had to work in depth on one of the early boards yet.

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I havent tried a patchwire board. I usually dont see those. 

 

I know there is a PAL set thats 6XX and a pal set thats 7XX and I have swapped the two before. 

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I swapped the PAL (all of them) and cleaned the pins, I swapped the  PAL sockets, I swapped all the 8 bit shift registers, I swapped the ROM SIM socket and I swapped the memory SIM sockets.

I replaced the capacitors and some of the resistors underneath the PAL chips.

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I noticed that there is a slight difference between the OP's screen output vs mine. My lines seem to go through the mouse icon and the question mark disk.

IMG_4269.JPG

IMG_4270.JPG

IMG_4271.JPG

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yea thats commonly fixed. If you have already changed out UE8, then check the traces to it. 

 

But more importantly, check the VRAM I have seen those go bad as well. 

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I think I found it Pin 5 on the ls166 (vid3) to UC7 pin 23 is OL. Pin 5 to via on the ls266 is OL. via to pin 23 on UC7 is .3ohm

a closer look reveals that the pad is disconnected from the Via

IMG_4273.thumb.JPG.eaaee88b9dd58ba8f8f4958fc460f7ab.JPG

thank you for the help  techknight

 

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