SE with startup chime, no display, burnt smell, recently recapped

[estravolta]

Hi all! I have an SE FDHD that I just did an analogeboard recap of, as well as reflowed the primary solder joints on the analog board. It has a new PicoPSU in it as well.

I just did a smoke test and did get a startup chime, but nothing on the display. Didn't see any smoke, but absolutely smelled a strong "burning electronics" smell. I'm letting it sit before discharging the CRT and inspecting, but not sure where to start with diagnostics.

The flyback looks to be a potential issue (glue is brown and cracked, some slight discoloration on the plastic near the top) would a bad flyback cause a burning electronics smell but no smoke?

Thanks for any assistance!

 

[3lectr1cPPC]

Welcome!

Can you post some high-res photos of your analog board and the flyback?

 

[LaPorta]

Welcome! Another question: was this a not working, full retires, or did it work before and now just not after the repairs?

 

[Byrd]

Double check the harness of wires that goes from the back of the yoke to the analogue board (red/blue/yellow/green) it's usually one of these pins that burns out and causes arcing on the analogue board - as evidenced by a brown/broken/rusty looking pin or connector. Even with resoldering I've had a couple of Mac SEs that needed a thick gauge trace wire to fix the damage. You can also tap the analogue board with a non-conductive item to see if the image jumps back up.

Check to see the rear of the CRT emits a glow in a dark room, and any arcing/lightning around the flyback as well. Bad flybacks usually look pretty worn in Compact Macs.

 

[estravolta]

Welcome!

Can you post some high-res photos of your analog board and the flyback?

Thanks for the welcome! I attached some photos of the analog board and flyback — it’s out of the computer now, so if these aren’t the right angles, I can take more. Thanks for your help.

I did reflow the solder on the flyback, as well as the yoke plug (P1). I think the yoke plug’s solder joint has some flux on it — but it could be burning or rust?

The three things I was eyeing (based on Dead Mac Scrolls and Macintosh Repair and Upgrade Secrets) is the yoke connector, the flyback, and Q3

 

[estravolta]

Welcome! Another question: was this a not working, full retires, or did it work before and now just not after the repairs?

Thanks! I've now powered it on three times, these were the results:

First: Chimed, screen flickered on, some distortion, no weird noises, saw the flashing question mark
Second: Would flick power on, nothing happened, when I flicked power off, it would roar to life and then die. Did that a few times, then it chimed, brief lines on screen and then no picture, some weird whining noises, smoke, burnt electronics smell.
Third (most recent): Chimed, no smoke, no noises (that I could hear -- we were outside for the smoke test), but a horrible burnt electronics smell.

After popping the case open this morning and sniffing around, the smell seems to still be lingering around the flyback.

 

[estravolta]

Double check the harness of wires that goes from the back of the yoke to the analogue board (red/blue/yellow/green) it's usually one of these pins that burns out and causes arcing on the analogue board - as evidenced by a brown/broken/rusty looking pin or connector. Even with resoldering I've had a couple of Mac SEs that needed a thick gauge trace wire to fix the damage. You can also tap the analogue board with a non-conductive item to see if the image jumps back up.

Check to see the rear of the CRT emits a glow in a dark room, and any arcing/lightning around the flyback as well. Bad flybacks usually look pretty worn in Compact Macs.

The yoke connector looks fine on the plugs (F and M sides) but the pin that's usually the culprit does have some brown gunk on the solder joint on the back. Thought it was flux, but maybe not. Posted a photo above. What gauge do you recommend? I have an SE/30 with this specific problem and someone did a shoddy repair job with a trace wire, but I think it's too thin of a wire.

Will check to see if the rear of the CRT emits a glow next power on! There is some lightening on the flyback that's in line with where arcing can be based on some videos I've seen of a bad flyback in a dark room. Posted a photo of that above too.

 

[bibilit]

You can also tap the analogue board with a non-conductive item to see if the image jumps back up.

I agree a 100 %

those joints on the picture 6027 doesn't look right, i will try a reflow...

 

[joshc]

That flyback has very high hours on it - you can tell because the glue is very dark. Doesn't mean it's totally worn out though, it can still work fine in that state.

those joints on the picture 6027 doesn't look right, i will try a reflow...

Agree with this

 

[estravolta]

That flyback has very high hours on it - you can tell because the glue is very dark. Doesn't mean it's totally worn out though, it can still work fine in that state.


Agree with this

There seems to be a crack in the flyback. Could it be fatal to the component? Attached a photo

I agree a 100 %

those joints on the picture 6027 doesn't look right, i will try a reflow...

Just took off the solder with solder braid and reflowed -- does this look any better? Did both the yoke and flyback joints. I believe the bit of brown remaining is just oxidation. (Still building my soldering skills...)