SE with failing flyback transformer?

[68kPlus]

Hi everyone,
I have a Macintosh SE (dual 800K). It appears to have it's flyback transformer failing.
I hear this high pitched whine come from the computer (when turning on sometimes), and the internal fan tends
to drop in speed, as if the power supply is struggling to power the HDD and both 800K drives.

The screen also tends to wobble occasionally, and appears to "glitch out".

Any thoughts on what to do?
I'll try to capture it on video soon.
Thanks,
68kPlus

 

[jajan547]

Sounds actually like the capacitors are starting to go. This is likely Power Supply related but I wouldn't be surprised if a cap or two are starting to go. It's defiantly worth replacing them. What's cool about the SE is the power supply separates from the analog board. These are a lot safer to work on than the earlier Macs as these have bleeders to diffuse the CRT, It's still important to do it though! I would start by ordering caps for the power supply and analog board at Console 5. I can see you use 240v, there were a few different iterations of the SE PSU so you'll need to share a photo for us to find you the right caps, same applies for the analog board. What's also cool is the people over at Console 5 will make a special cap kit specific to what's on your analog board or power supply you just need to reach out to them, I say this because sometimes they don't have premade kits for what you have but they will put one together.

 

[AwkwardPotato]

Interested in seeing the video of it "glitching out" but it's almost certainly a power supply issue rather than a flyback one. Flyback failures are rare in SEs and SE/30s; generally speaking it's the airflow-starved systems like the 128-512k-Plus, or much further down the road, the G3 iMacs, where they're a problem. If anything the power supply is the weak point in the SE and everything else in them tends to be pretty much bulletproof.

If the flyback was toast, you most likely wouldn't get an image on screen, and would hear a constant chirping/ticking noise, or you would get a horribly unstable image accompanied by the flyback arcing out. Definitely plan on getting the PSU recapped (or replaced with modern equivalent) and the analog board as well, they are known to need it at this point. If it still has problems afterwards, further troubleshooting will be needed; a replacement flyback should be your last resort because they are expensive nowadays, usually more than the cost of another SE.

 

[68kPlus]

Thank you very much for the help guys!
The reason I thought it was the flyback was because my friend (who gave me the SE), said he has had the high pitched whine and after that the machine magic smoked and he believes the flyback was the cause.
Console 5 costs too much to ship here so if anyone has a cap list for the SE that would be very much appreciated!
I'll get to work dissembling the SE soon.
Thanks again you guys!

 

[68kPlus]

Okay I've ordered the caps. The PSU is a Sony CR44M.

Does the massive 620uF cap need replacing?

These are the capacitors I got:

element14 Part Num.	Qty. ordered	Product description	Mnfr Part #
2346505	3	16PK2200MEFC10X20 CAP, 2200µF, 16V, 20%	16PK2200MEFC10X20
9451820	1	MCRH25V476M5X11 CAP, 47µF, 25V, 20%	MCRH25V476M5X11
9452648	1	MCMHR16V107M6.3X7 CAP, 100µF, 16V, 20%	MCMHR16V107M6.3X7
1902914	3	MCRH25V226M5X11 CAP, 22µF, 25V, 20%	MCRH25V226M5X11
9451676	1	MCRH10V338M13X21 CAP, 3300µF, 10V, 20%	MCRH10V338M13X21
1902887	1	MCGPR10V478M13X26 CAP, 4700µF, 10V, 20%	MCGPR10V478M13X26
9451110	3	MCGPR16V477M8X11 CAP, 470µF, 16V, 20%	MCGPR16V477M8X11
9451358	1	MCGPR50V105M5X11 CAP, 1µF, 50V, 20%	MCGPR50V105M5X11
3131974	1	860020280027 CAP, 6800UF, 10V, ALU ELEC, RADIAL	860020280027
2495099	2	860131275004 CAP, 4.7µF, 350V, 20%	860131275004

 

[jajan547]

Okay I've ordered the caps. The PSU is a Sony CR44M.

Does the massive 620uF cap need replacing?

These are the capacitors I got:

element14 Part Num.	Qty. ordered	Product description	Mnfr Part #
2346505	3	16PK2200MEFC10X20 CAP, 2200µF, 16V, 20%	16PK2200MEFC10X20
9451820	1	MCRH25V476M5X11 CAP, 47µF, 25V, 20%	MCRH25V476M5X11
9452648	1	MCMHR16V107M6.3X7 CAP, 100µF, 16V, 20%	MCMHR16V107M6.3X7
1902914	3	MCRH25V226M5X11 CAP, 22µF, 25V, 20%	MCRH25V226M5X11
9451676	1	MCRH10V338M13X21 CAP, 3300µF, 10V, 20%	MCRH10V338M13X21
1902887	1	MCGPR10V478M13X26 CAP, 4700µF, 10V, 20%	MCGPR10V478M13X26
9451110	3	MCGPR16V477M8X11 CAP, 470µF, 16V, 20%	MCGPR16V477M8X11
9451358	1	MCGPR50V105M5X11 CAP, 1µF, 50V, 20%	MCGPR50V105M5X11
3131974	1	860020280027 CAP, 6800UF, 10V, ALU ELEC, RADIAL	860020280027
2495099	2	860131275004 CAP, 4.7µF, 350V, 20%	860131275004

Should be okay but it's better to replace them all and take care of any future gremlins whilst you are in there.

 

[68kPlus]

Should be okay but it's better to replace them all and take care of any future gremlins whilst you are in there.

I've actually decided to not replace the 620uF one because I don't think my soldering iron can handle such large solder pads. I tried once on smaller stuff and it couldn't even handle that.
Once I get a better solder station I'll get to work replacing that big guy.

 

[jajan547]

I've actually decided to not replace the 620uF one because I don't think my soldering iron can handle such large solder pads. I tried once on smaller stuff and it couldn't even handle that.
Once I get a better solder station I'll get to work replacing that big guy.

Definitely pick up some solder wick but don't cheap out on wick, good wick makes a huge difference. I don't think the large pads should cause issues.

 

[AwkwardPotato]

The 620uF cap generally doesn't fail in these. If you do replace it in the future, be aware that any appropriate replacement you can find (which are generally going to be 680uF rather than 620uF) will most likely require new holes to be drilled into the board for it to fit.

 

[68kPlus]

The 620uF cap generally doesn't fail in these. If you do replace it in the future, be aware that any appropriate replacement you can find (which are generally going to be 680uF rather than 620uF) will most likely require new holes to be drilled into the board for it to fit.

The hole issue is the main reason I was avoiding it. Thanks so much for the info! Any idea what the high pitched whine is though?

 

[68kPlus]

Interested in seeing the video of it "glitching out" but it's almost certainly a power supply issue rather than a flyback one. Flyback failures are rare in SEs and SE/30s; generally speaking it's the airflow-starved systems like the 128-512k-Plus, or much further down the road, the G3 iMacs, where they're a problem. If anything the power supply is the weak point in the SE and everything else in them tends to be pretty much bulletproof.

If the flyback was toast, you most likely wouldn't get an image on screen, and would hear a constant chirping/ticking noise, or you would get a horribly unstable image accompanied by the flyback arcing out. Definitely plan on getting the PSU recapped (or replaced with modern equivalent) and the analog board as well, they are known to need it at this point. If it still has problems afterwards, further troubleshooting will be needed; a replacement flyback should be your last resort because they are expensive nowadays, usually more than the cost of another SE.

Also I've taken it apart already, so unfortunately I won't be able to get footage if the recap works.

 

[joshc]

what the high pitched whine is though

If you run the machine with the rear cover removed, is it easier to tell where the noise is coming from?

 

[tecneeq]

As for the recapping of the power supply, it should be noted that it's easy to replace it with a modern flex atx one, these can be had for 40€ and up. It would even fit into the old one if you would gut it.

 

[68kPlus]

As for the recapping of the power supply, it should be noted that it's easy to replace it with a modern flex atx one, these can be had for 40€ and up. It would even fit into the old one if you would gut it.

Unfortunately they cost $100+ here.

 

[68kPlus]

My caps arrived today, so I'm going to recap the PSU.

 

[68kPlus]

Okay recap complete! The issue appears to be gone, but I don't know for sure as I haven't used it much since recapping.
See this post for more on it:

Mac SE PSU (Sony CR44M) recap success story

Hi everyone, I've never done soldering work on an SE before, so this was a new experience for me. My SE (which I got in early 2021) had been showing some signs of power supply failure: -Inconsistent fan speed -Wobbly screen -Disk drive trouble (it had trouble reading disks and writing to...

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