SE/30 Chime but black screen

[bibilit]

I have a SE/30 with the above issues.

In the first place i had no video and faint sound, replaced caps on the logic board, now have very loud chime but still no video.

Replaced UE8 also, still same issue.

The Analog side is ok, tested with a good logic board.

Screen is all black.

Any idea ?

 

[CelGen]

Have you verified the tube has even got a lit heater?

 

[BadGoldEagle]

I don't think the tube's the problem. I happen to have the exact same symptoms with one of my SE/30 boards. UE8 has been replaced too. 

I sent it to techknight's with the Portable Logic board a couple of months ago. Maybe he can help?

 

[bibilit]

The tube is OK, tested with another board.

i have tested a couple of things, the obvious ones (Ram and Rom, Video Rom) a bit lost right now.

 

[Elfen]

Have you checked the plug in jack on the logic board? True this section fails in the Analog Board a lot, but it also fails in the logic board too. Just desolder, clean up and resolder the connection.

 

[bibilit]

Can have a look, but not confident.

thinking about Vram in the first place.

 

[techknight]

I had this happen twice. One time it was PALs, and another time it was the output pin trace from UE8 broke. 

 

[Ferrix97]

I had two boards with the same issue (one with no video at all, the other with partial video), replacing UF8 and UG8 solved my problem.

Actually, the no-video one wasn't even able to boot and could not be tested with a TechStep.

https://68kmla.org/forums/index.php?/topic/22545-macintosh-se30-killed-by-a-mouse/?p=302607

 

[bibilit]

Hi,

Great, thanks, i did see your post but was focused on the partial video one, didn't realised there one one with a black screen as well.

 

[Ferrix97]

Yeah, I bought a second board for replacing the first one

but it turned out that the second board had more problems than the first one

 

[bibilit]

thanks to all of you.

Yesterday spent all the evening looking for broken traces, all was ok.

Following the advise of Ferrix i removed and replaced both UF8 and UG8, the screen lit up   but scan lines were present, just like my last one:

https://68kmla.org/forums/index.php?/topic/28003-mac-se30-screen-too-bright-with-scan-lines/

so removed again UE8, cleaned all pads again and soldered back.







In the end, i think all of them were bad.

once all was put back together :



Still have a small problem with floppy drive, but no big deal.

 

[Ferrix97]

Great!

It looks like those video issues are getting more and more common, probably because those ICs don't like capacitor goo around them.

Out of the three boards I have, two of them had the same issue as yours, and the third one had a broken Data line on the SCSI IC.