My SE/30 died!

[Byte Knight]

I was using my SE/30 today when a "lightning bolt" shot down my screen and then it went blank.  I turned it off and back on again but all I get is the fan - no boot chime.  I'm getting 5.0V at the external floppy port, so I'm assuming this is an analog board issue.  The Dead Mac Scrolls confirms this, and I've tested the barrel rectifier at CR2 and the transistor at Q2 which seem good.  It looks like the next step is replacing the flyback transformer.

Should I do this or replace the capacitors on the analog board next?  If I need a flyback where can I get one?

Thanks in advance!

 

[jessenator]

I don't have the p/n on hand (mobile) but I have seen them and they aren't cheap.

Hopefully someone chimes in with the part number—Here's the thread post about numbers:

 

[Byte Knight]

I've got the part number (157-026C Flyback) and they go for $99 on ePay.  But I don't even know for sure if that's my issue.  I think I'll clean up the solder on the flyback and replace the capacitors and see what shakes out, unless someone has a better idea...

 

[techknight]

just a couple years ago they were only maybe 10 to 20 bucks. the demand probably sent the prices soaring through the roof. 

The "lightning bolt" effect you saw was a sudden loss of scan voltage without the beam killer circuit activating. Aka, the horizontal stage failed in some weird way. Or even the power supply's 12v rail disappeared. 

 

[Byte Knight]

So I replaced all the caps and the flyback on the analog board, and it worked for a couple of minutes before it died again - nuts...  There's now a hissing noise, and DMS suggests testing the barrel rectifier at CR2.  I get continuity through the barrel rectifier for about 2 seconds, then the ohms start climbing and then my multimeter overloads to 0L but no continuity sound.  Does this mean it's good or bad?

 

[Byte Knight]

And I should also say this happens in either direction.

 

[Byte Knight]

Well it's not that either - I swapped out the working barrel rectifier from my Classic analog board and got the same result...

 

[techknight]

the initial failure wasnt resolved that took out the first flyback. So I would hate to think about this, but you may have taken out the 2nd one. 

Not sure what the Hissing sound your describing is, could be many things. Could be diodes, capacitors, anything on the horizontal section, Up until, and including the sync gate logic IC. Without a scope, no way to know what the horizontal drive signal looks like to know if its correct or not. It has to be chased through the stages to find out where it gets screwed up. 

Because "hissing" means noise, and ALOT of it... 

Also a broken, gone to air CRT will do that too, but it would be more arcing than hissing. 

 

[Byte Knight]

I was able to find a cheap Mac SE with a dead HD on Craigslist and used the analog board from it.  All is good again for now...

 

[Byte Knight]

And this is why I said "for now"...  The screen just cut out again after 3 days and it won't come back on.  It turns out that it's not the analog board, as my SE logic board works just fine with it.  Any idea what would cause such intermittent issues?  Just before the SE/30 died I noticed that the serial ports were only intermittently working...

 

[Bolle]

I would say you might hav me a trace with intermittent contact somewhere on the logicboard.

Had this happen before and it was a pain to find it because it would measure just fine on the first two times checking every trace in the video section. There was a break right where a trace connected to one of the solder pad of one of the video address muxers.

A hissing sound might indicate that the board isn’t outputting a correct sync (probably hsync) signal. I think this can happen if you got an issue with one of the binary counters UF8 and UG8.

I once accidentally shorted two pins on one of the counters while measuring some stuff and this made the video drop out while the analog board emitted some unpleasant noise.

Can you get a high res picture of your logicboard? If you’re lucky we can see something.

 

[Byte Knight]

I would say you might hav me a trace with intermittent contact somewhere on the logicboard.

Had this happen before and it was a pain to find it because it would measure just fine on the first two times checking every trace in the video section. There was a break right where a trace connected to one of the solder pad of one of the video address muxers.

A hissing sound might indicate that the board isn’t outputting a correct sync (probably hsync) signal. I think this can happen if you got an issue with one of the binary counters UF8 and UG8.

I once accidentally shorted two pins on one of the counters while measuring some stuff and this made the video drop out while the analog board emitted some unpleasant noise.

Can you get a high res picture of your logicboard? If you’re lucky we can see something.

For some reason it's no longer making the hissing sound.  Tonight it booted up and then cut out after a few seconds, then popped back on with an "A System Error Occurred" for a few seconds, then the screen went out again.   After that I tried turning it on several times and the fan came on but no video, no startup chime, and no HD activity.  My SE board still works fine, so looks like I'll be an SE guy for a while...

Here are some pictures of the logic board, complete with my successful kludge fix for vertical pinstripes:

 

[Byte Knight]

Fast forward 6 months - I threw this board in the dishwasher just to see if I could salvage it.  I've been using another SE/30 logic board in the meantime.  The problematic logic board works again!  All except for the serial ports.  ADB and SCSI ports are fine, but no serial activity.  Any idea what would cause the serial ports to fail?

 

[Garrett]

I know it's been a while, but I noticed some discoloration (scorch marks?) near C9 and the molex connector in the second-to-last photo. Maybe that was part of the cause?

Also, don't forget to remove that battery if it's the original.