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Here's a short video of the weirdness I get when I connect pin 13 to 12 on UE8... otherwise the screen is black.

When I connected UE8 pin13 to the neighboring pins 12 or 14, the screen lit up, but it was a mess...I could roughly make out what would be a flashing disk icon and cursor though..and I could move the cursor. I'll upload a picture when I get home.

yeah, I will post a picture tonight thanks but I do recall either vertical or horizontal jail bars

Finally got a logic board connector extension, so I was able to play around with UE8 live... upon testing some of the voltages with a multimeter, the video came to life when I accidentally touched pin 13 to 12 (or14)..... although it was garbled, I could make out the flashing disk icon...and the...

I found something suspicious in my ROM socket (see photo). the board chimes and boots fine but I get no video at all - total blackout. I've been going through potential issues in the video circuit. Is it possible that this is the cause?

got it. Thanks again for your help. I enjoy your channel also!

I didnt realize it but UF8 and UG8 are 14 pin chips but the rest are 16 pin chips. Are we certain that A-E are the same?

All of my pins on UE8 have continuity to where they should go..PAL , +5 , ground

Thanks! I've cleaned all the black and green I can find on the board. Check continuity on all vias near all the U*8 chips and that's fine. I realize there are still traces I need to check but my big question is: Is there anything on the logic board that would cause a chiming/booting board to...

Thanks!

thanks. Where would I find these files? Is there one for the video ROM as well?

Does anyone know about replacement PAL and Video ROM chips?

Thanks!

Glad I found this...what about UC8 or UD8? Looks like I might be replacing UD8. Thanks for any help.

What am I looking for on Mouser for UD8, UE8, UF8 replacement chips? Can I also buy replacement PAL chips on Mouser? These do not need to be programmed? And a chip to program as a Video ROM replacement? I'm sure I won't need all of that but since chips aren't that expensive I might as well...

once I loaded the boot disk, it is responding to key commands like "Apple Q" to quit the installer and eject the disk.

nope. Totally new to the video side of these boards. How would I do that? Thanks for your help.

I cleaned and restored the floppy drive also. I put a disk in it that I knew did not have a system and it ejected it as it should. Then I tried a system disk and it seemeed to boot, although of course I can't see the screen. reset button works also.

Do you know anyone who sells them? I wouldn't mind having a few spares.

That may be my next step. It pains/scares me to pull the chips out of a perfect board. How hard is it to find Video ROM and or PAL chips? If they are tough to replace I may just replace UD8, UE8 and UF8 and see where I'm at.