SE/30 Board Mystery Issue

[smrieck511]

Heres an overview of what (I think) I know so far...

Analog board, CRT and PSU are fine. They work with other SE and SE/30 logic boards and have been recapped.

No video - occasionally displays random dots, snowflakes, static...(see attached video). Then calms down and stays dark.

It chimes. The logic board recap fixed the sound but didnt seem to have any affect on the video problem.

I've cleaned the board with IPA several times.

I've taken the video chips and Video ROM out deoxed, ipa and reseated. There was no sign of corossion on any of the pins of those chips.

UE8 looks reasonably ok.

What should be my next steps? Sorry the video side of repairing these boards is completely new to me.

Thanks for any guidance.

 

[rickrob]

Did you try the video chips/ROM from a good board in this one?

 

[smrieck511]

Did you try the video chips/ROM from a good board in this one?

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.

 

[obsolete]

That may be my next step. It pains/scares me to pull the chips out of a perfect board.

You'll get used to it

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.

Not hard. New/NOS chips can be programmed to replace them.

 

[rickrob]

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.

UG6, UE6, UE7 -- should be in sockets. video ROM too. Shouldn't be that bad-- try removing from the bad board first so you get a feel for it.

 

[smrieck511]

That may be my next step. It pains/scares me to pull the chips out of a perfect board.

You'll get used to it


Not hard. New/NOS chips can be programmed to replace them.

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

 

[smrieck511]

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.

 

[finkmac]

have you used a multimeter to verify the connections of the video multiplexers, especially UE8?

 

[smrieck511]

have you used a multimeter to verify the connections of the video multiplexers, especially UE8?

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

 

[smrieck511]

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

 

[rickrob]

check around C7 and UF8 for trace damage or shorts? I think C7 is pretty close to a trace going to UF8

 

[smrieck511]

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 get it all in one shipment.

 

[Kouzui]

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

Check the schematics and tap your multimeter to each of the chips where the traces say they should lead. If you have continuity, move on to the next trace, and so on and so forth.
I had to do it to get a (admittedly less severe) video issue fixed with my own SE/30.

Relevant schematics and such are in this thread: https://68kmla.org/bb/index.php?thr...before-and-after-recapping.46258/#post-523364

Fixing traces is WAY easier than pulling and testing chips, even if it takes a long time to check them all.

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 don't recall any of those being purchasable, but I haven't double-checked.

 

[smrieck511]

Check the schematics and tap your multimeter to each of the chips where the traces say they should lead. If you have continuity, move on to the next trace, and so on and so forth.
I had to do it to get a (admittedly less severe) video issue fixed with my own SE/30.

Relevant schematics and such are in this thread: https://68kmla.org/bb/index.php?thr...before-and-after-recapping.46258/#post-523364

Fixing traces is WAY easier than pulling and testing chips, even if it takes a long time to check them all.


I don't recall any of those being purchasable, but I haven't double-checked.

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 have a total blackout besides U*8 , PAL and Video ROM chips?

 

[smrieck511]

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

 

[finkmac]

the reloaded board is electrically identical for stuff like this
i use these schematics

 

[smrieck511]

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 cursor moves fine with the mouse.

From that, would it be correct to conclude that the problem is isolated to the U*8 chips or their traces?

 

[rickrob]

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 cursor moves fine with the mouse.

From that, would it be correct to conclude that the problem is isolated to the U*8 chips or their traces?

Depends on what the video looks like, UE8 usually is a vertical jailbar pattern on the screen. (Every Nth dot missing). can you get a pic of the video?

 

[smrieck511]

Depends on what the video looks like, UE8 usually is a vertical jailbar pattern on the screen. (Every Nth dot missing). can you get a pic of the video?

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

 

[Kouzui]

Depends on what the video looks like, UE8 usually is a vertical jailbar pattern on the screen. (Every Nth dot missing).

Yup.

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 cursor moves fine with the mouse.

From that, would it be correct to conclude that the problem is isolated to the U*8 chips or their traces?

Fascinating; where did you tap the probe? It sounds like the issue really is related to the traces. (If the pattern is indeed a vertical jailbar).