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Mac SE/30: Looking for suggestions for next steps

Posted by: kjoh on 2022-09-18 12:19:08

History, symptoms: Came to me with leaky caps on the logic board. Replaced surface caps with tantalums, and repaired known bad traces.

The computer bongs on power up along with hard disk and floppy activity, but usually no video. Occasionally I will get a screen like the one shown. Adjusting the brightness changes how bright this pattern is, but I never see a sign of an actual video signal (eg no question mark floppy).

Upon inspection of the analog board, I found numerous cracked solder joints, which I have reflowed, to no effect.

I have chased down and/or swapped the usual culprits on the analog board (U1, R25, CR6) and the neck board (Q1), all seemingly good. Random checks of diodes, resistors, electrolytics on the analog board have not yielded anything. I have not checked the diode and transistor attached to the flyback shield, but that will be my next step. They appear physically intact and not overheated.

Do you think I may not yet be done with logic board repairs? I wonder if there are other bad traces that I have not yet discovered.

Thanks in advance for reading.

Posted by: Juror22 on 2022-09-18 14:17:59

You didn't mention whether or not you had washed the logic board and to what extent. I've had a couple of recapped SE/30's that did not immediately respond to recapping, before I learned the extent to which the exudate from the caps can do damage, but also how it is able to remain on a board after the visible areas have been cleaned. I ended up washing one of mine three times before I got it right, although my symptoms were more in line with standard simasimac and a sound issue.

Posted by: kjoh on 2022-09-18 14:33:17

You didn't mention whether or not you had washed the logic board and to what extent.

Ya, hi, aside from some light toothbrush scrubbing with IPA on visible areas, I did not wash the board. There was electrolyte juice everywhere, and I did not touch anything hidden under ICs, so maybe that's a thing to look at, thanks.

Posted by: imactheknife on 2022-09-18 16:33:41

in my personal experience with two se/30 boards, they aren't fun. I had one I bought that had the nasty lines in screen. It had cap leakage. I cleaned board very well, cleaned pads, and recapped. It gave me the nasty screen. I thought it wasn't working. Next time I let sit for a bit and next thing I know it chimed and regualar screen came up and booted. I pulled board, and decided to pull off a few ic chips around the bad caps. I clean all those pads, checked traces, and still same screen for like 10-12 seconds then chime and boot up. It works awesome, have no idea what the screen at startup is. Once going, a restart starts normal with chime.

2nd machine was nasty to for cap goo. I removed caps, and ic chips right off the bat, cleaned all pads, then cleaned whole board in tub of isopropyl and let dry. I recapped and put ic chips back on. It worked but still gave me horizontal lines. I remember from my classic recap that the horizontal lines were ram related. So, cleaned all ram pins, and slots on logic board, washed again and she works beautiful now.

Those lines to me look like analog board, but I am no expert on that matter. Every analog board I recapped is giving me grief. Two classic boards to be exact.

I do recommend pulling anything off that's removable, and any ic chips that had massive cap goo and clean board again. check traces around any ic that you take off to be sure.

Posted by: moldy on 2022-09-19 04:51:11

Those lines to me look like analog board, but I am no expert on that matter. Every analog board I recapped is giving me grief.

That might be the analog board, but I have seen identical lines on an SE/30 with a broken ICs in the UE8/UF8/UG8 row (those 3 specifically were in a particularly bad shape). I just replaced them all and the computer is reliably happy.

Posted by: bibilit on 2022-09-19 06:58:40

I agree with Moldy

UE8 first then UF8/UG8

UE8 is contaminated by cap goo and as you are getting the Chime the board is mostly working.

Not related with the AB board

Macintosh SE/30 no Display

Logic board issue for sure, new caps, I have a chime but screen remains black. Ls166 replaced, traces checked around but have not found so far. Any idea ? With another logic board, screen is ok.

68kmla.org

How I revived a poorly SE/30

Earlier this month I made an impulse purchase of something I'd always wanted: a Macintosh SE/30. I've been trying to find a good deal on one of these machines for half a decade or more but they simply keep getting more and more expensive in working condition. I finally decided that I was going...

68kmla.org

Posted by: kjoh on 2022-09-19 07:12:24

UE8/UF8/UG8

Yes, those are notably crusty, and closest to the worst of the capacitor leakage.
And thank you bibilit for your response and those forum links.
I guess I'm going to be shelling out for a hot air station.

Posted by: Garrett B on 2022-09-19 07:38:45

I had this exact issue, but with a Mac Classic. Turned out to be a bad trace to pin 6 of the logic board molex plug (which corresponds to VIDOUT). Ran a small jumper wire to restore the connection and all was good.

Posted by: kjoh on 2022-09-19 08:14:38

VIDOUT

That sounds like a logical place to start, thank you.

Posted by: kjoh on 2022-09-19 11:13:49

Hi, all. The VIDOUT and HYSNC to the molex plug were fine.

HOWEVER, ringing out pins on the UE8 show that pins 2 and 7 don't make it to where they're supposed to. I'll bodge in some wires, and see what happens.

Posted by: kjoh on 2022-09-19 11:35:14

Holy crap, it's booting!!! I am beside myself, thanks guys!

Posted by: aeberbach on 2022-09-19 18:40:22

I bet that felt good!

Posted by: joshc on 2022-09-20 02:06:33

Woohoo! Great to see another SE/30 going again.

Posted by: kjoh on 2022-09-20 06:03:06

Woohoo!

I bet that felt good!

That pretty much sums it up, lol.

Posted by: imactheknife on 2022-09-20 19:07:44

sweet, good job!