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Help with M1212 Display

Jockelill

Active member
Hi!
New to the forum here, but hoping to get some advice.
In my collection of old macs, I have 2 M1212 display. Both are in working order, but they make a quite annoying high pitch noise. I don’t think it’s the usual “coil wine”, because the frequency is much lower.
I’ve identified it to the high voltage transformer, and posted a small video below.

my question Is simply, any advice on how to get rid of this problem?


A8BDBD1B-AD09-4F4C-9128-21515AD53A29.jpeg

9032EDFF-7A89-42C2-AB9C-A3F7D537E97E.jpeg90750B66-51B1-42EC-8D6B-36005F9A46B9.jpeg
Any help is highly appreciated!

br
Joakim
 

Byrd

Well-known member
Hi Joakim,

In a dark blacked out room can you notice any arcing (small sparks, flashes) coming from the flyback transformer (where you are touching)? If so these will eventually need replacement; I'd also reflow solder on the underside. Dust too won't help - time for a good blast out using compressed air.

After a re solder if it seems OK and the monitor is performing well, there is special epoxy/high temp hot glue you could use to stop the vibrations and whining around the flyback.

JB
 

Jockelill

Active member
Thanks for the tip, I’ll try it again in a dark room. Yeah, it needs cleaning for sure! I did recap my other M1212 and cleaned it thoroughly, but it’s making the same noise. Haven’t tried the reflow, but I’ll give that a try as well.

If the flyback needs replacement, are these available somewhere?

do you know the brand of that glue?
 

Byrd

Well-known member
A high temp silicone sealant would do, at a pinch the high temp hot glue sticks.

The later the monitor the better chance of finding a cheap flyback - google or eBay the part no.
 

9166188

Well-known member
My M1212 also suffers similar noise issue. Did yours get fixed with silicon sealant and re solder?
 

Jockelill

Active member
Haven’t tried it yet, but I got some high temp epoxi yesterday that I will try out. I’ll keep you posted. Interesting is that also one of friends has one of these monitors and it does exactly the same, so seems “common” 😀
 

Jockelill

Active member
Hi Joakim,

In a dark blacked out room can you notice any arcing (small sparks, flashes) coming from the flyback transformer (where you are touching)? If so these will eventually need replacement; I'd also reflow solder on the underside. Dust too won't help - time for a good blast out using compressed air.

After a re solder if it seems OK and the monitor is performing well, there is special epoxy/high temp hot glue you could use to stop the vibrations and whining around the flyback.

JB
No arching what I could, I tried in a dark room:), but of course it can be internally.
 

9166188

Well-known member
According to this video, flyback transformer tends to go bad eventually. Is it possible to get a new compatible replacement nowadays? Looking at ebay, they don't seem to me having the same pins out configuration to fit necessarily and some have two adjustment knots not present in the original one in M1212. Any pointers to the right replacement appreciated!
 

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claanu

Active member
I have the same squealing on my M1212, definitely the flyback. Seems like they're all falling victim to this trouble. The most likely source for a replacement would be someplace like HR Diemen. Seems they don't stock the exact replacement transformer anymore, but it's possible they have another one that'd match or could be adapted to fit this board.

 

Jockelill

Active member
By coincidence I noticed a burnt resistor on one of mine. RL34, does anyone know the size of this? Or maybe someone has a schematic for the display?
I have reflown my flyback and if it does not help, I will attach it with epoxy.
 

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Jockelill

Active member
One weird thing, my other M1212 does not have RL34! So must be different revision.
I did remove the resistor and it measures 22ohm in burnt condition, first line is red , so 22ohm does not sound very implausible, but a schematic would of course be nice 😀
 

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