Weird issue with a client's SE/30

[phreakout]

Okay, I had completed a recap of the logic board for member of this forum. New capacitors in place and thoroughly cleaned of debris. I go to attach the board to my test chassis for the 24 hour test, turn it on, I hear the normal startup tone, hard drive booting the machine up, but no normal video. I get this.

Fearing it might be anything listed under the diagnosis, I decided to try the same board in a second SE/30 I bought earlier this year that I know works 100% without issues (the so-called "control"). So I swapped out the logic boards, turned it on and still get the same issue. So it's not a problem with any of the analog boards on both SE/30s I've got; the originating logic board from the second SE/30 works perfectly fine: no Simasimac, full loud audio and normal video.

Now here's some things to note. If I start up using the client's board and move the mouse to the bottom left hand corner of the screen, it will trigger the After Dark screensaver I set up initially. I can then hear Flying Toasters, but still the same video issue.

My question to everyone out there: Has anyone experienced this problem before after a board recap? If so, what did it turn out to be?

While I await an answer back, I'll recheck all the soldering I did during recap. Maybe something is shorting out or it's something else.

Thank you!

73s de Phreakout. :rambo:

 

[zuiko21]

I can't tell for sure, but here's a thought...

Since the issue looks like analog but you discarded that possibility with your "control" machine, the only thing I can think of (you checked the board connector, didn't you?) would be the path between the analog board and the place of actual video generation.

Video output is digitally generated at pin 13 of UG6, then it goes thru R21, R22 with R20 and C40 between that signal and ground -- these passive components are worth checking, IMHO.

However, a properly timed but weirdly shaped sync signal might have similar effects... VSYNC goes straight from pin 14 of UG6 to the AB, while HSYNC has R24 between pin 13 of UG7 and the AB. Check these too.

Hope this helps,

 

[phreakout]

Yeah, I'll check those out in a little bit and report back. Thank you!

73s de Phreakout. :rambo: