• Hello, Guest! Welcome back, and be sure to check out this post for more info about the recent service interruption and migration.

Mac SE: "zoomed" display, dim, high pitch whine

Brett B.

Well-known member
I have been using this SE as a clock at my office for 10+ years and other than one blown cap on the analog board that I fixed, it's been working great. I came back from an appointment last week and immediately noticed that the screen was very dim and appeared to be way too large.

I took it home, and attempted to adjust the horizontal, vertical, and brightness cutoff. The brightness adjustment is just about maxed out but "acceptable..." and I was able to make the height much better, but the width is almost non-responsive. Once I get to the very ends of the barrel screw, the image moves a tiny bit in either direction, but I can't shrink it enough. Additionally, after running for a couple minutes, I get a really high pitched whining noise from around the flyback transformer.

I tried reflowing the solder joints on the analog board and CRT connector... didn't make much difference although I did find two that were cracked.

Any ideas? Dead Mac Scrolls didn't have anything about issues like this.

KIMG0904.JPG
 

CircuitBored

Well-known member
This has the hallmarks of a failing flyback transformer. I've never seen bad caps cause zoomed image, although someone may chime in to correct me on that. The lack of response from the screen adjusters is rather telling. It's possible that you have capacitors in there which are on the way out but I'd expect far more significant and inconsistent levels of distortion from bad caps.

Buy a new flyback transformer. You're going to need one eventually anyway (if you plan on keeping this Mac indefinitely). If you want to be really prepared for the future buy two new flyback transformers. It's a component that is guaranteed to fail some day so it's wise to plan for that.
 

desertrout

Well-known member
Agreeing with @CircuitBored. The only issue is that new flybacks are not really available for a reasonable price ($150USD is the cheapest I've found, and that's pretty steep imo) - unless you know of a good source?

Otherwise, keep an eye out for a used analog board - one from any compact up to SE/30 will have what you need. Note most of these flybacks have a yellow sealant at the top of the coil - if it's gone brown, it's usually a sign the flyback is on it's way out (not definitive, but a typical correlation). If it's still yellow, that usually corresponds to a good flyback.

But yeah if you want one guaranteed to work: https://www.ebay.com/itm/121655780759?hash=item1c533fe597:g:CNUAAOxy14VRWxL3
 

joshc

Well-known member
I'm not convinced this is a flyback issue. Pictures of the front and back of the analog board would be good.

You said some caps on the AB were replaced, but not all of them? Worth a full recap first to rule out caps. 10 years fairly constant use is a lot for one of these at this age.

If you already found some cracked solder joints on the AB, there are probably more - and sometimes they are really hard to see. Reflow everything on the board to be sure.

I assume the power supply also hasn't been recapped? What voltages do you get from the floppy port?

1637957812489.png
 

desertrout

Well-known member
@joshc makes an important point - before jumping to a conclusion about the flyback, it makes good diagnostic sense to ensure everything else is in proper working condition, which at this stage includes replacing capacitors in the AB and PSU, then doing baseline adjustments.
 

Brett B.

Well-known member
I'm not entirely sure it's the flyback either but the whining noise makes me suspect it.

The part I replaced previously (I think) was the capacitor at C15. IIRC it had the "bright vertical line" symptom.

I did reflow every joint on the analog board and the yoke connector. I added a touch of solder to each of them as well. I should just recap everything, can't hurt...that would be the cheap route at this point.

10 years is a LOT for one of these, yes. I am shocked it lasted that long. I'm half tempted to just part it out... the only reason I ran it this long was because the screen was super burned in to begin with, and it's exponentially worse now. If I can fix it with a cheap re-cap, I'm game, but IMO it's not worth fixing if I've gotta drop $150 on a flyback transformer.
 

Johnnya101

Well-known member
Definitely the flyback. You've had it on 24/7 for TEN years!? I'm shocked it lasted that long too!

The flyback has some insulation inside and as it gets older/wears out, it breaks down and starts whining, like what you're hearing.
 

Brett B.

Well-known member
Definitely the flyback. You've had it on 24/7 for TEN years!? I'm shocked it lasted that long too!

The flyback has some insulation inside and as it gets older/wears out, it breaks down and starts whining, like what you're hearing.

I like pushing my luck, lol. Yes, I put it on a shelf in my office sometime in '09, '10, or thereabouts and had it running the Clock program off a floppy boot disk. The only time it was powered off was during random power failures, the one time I had to fix the C15 capacitor, bi-annual reboots to keep the floppy drive lubed around daylight savings time, and a couple times to blow the dust out.

10 years is 87,600 hours.... 75 watt estimated power use, 6,570 kW/h, @ 11 cents per kW/h, it cost me about $722 to test it's longevity. :LOL:

Plus whatever run time it had before I got it. It might have double or triple that many hours on it... I think it was a school surplus machine.

I should just fix the damn thing and run it another 10 years.
 

Johnnya101

Well-known member
You should! I'd just grab a cheap analog board off ebay or here (Or ive got one too), and swap out the flyback. You could swap the whole board out too, but that ruins the longevity test. :)
 
Top