Apple Cinema HD Display LCD 23" (A1082) with 24V power supply (A1097)

[joman50]

Re: Apple Cinema HD Display LCD 23" (A1082) with 24V power supply (A1097)

The PCB is densely populated and double sided, so it’s very difficult to see the tracks on the component side when the components are mounted. I’ve rechecked it with multimeter and the film capacitor is in parallel with the primary HV filter capacitor. Don’t ask me why. I checked the primary voltage while the power supply was failing and the 320V DC were there (230V AC mains here), so apparently there wasn’t anything wrong.

The capacitor is almost identical to the one that fails on Yamaha receivers (several models affected), pictures here:

https://www.avforums.com/threads/yam...oblem.1533016/

The only difference is that the one from Apple’s power supply has tolerance J (5%) and Yamaha’s is K (10%). I’ve replaced it with a K.

I remember that I knew about this failure two years ago through a Yamaha’s service bulletin. It could be extrapolated to several models of receivers and sound bars. No power? Just find if the PSU has the famous 22nF 630V film cap in primary section and 90% you’re done. Never thought that could even be extrapolated to something so different like this.

After reading the post about the infamous bad 22 pf cap, with nothing to lose, I gave this a shot. Lo and behold, it worked. Remember to plug in the video usb connectors. Too bad I ordered a 24v LED power supply. But hey it only costed 10 dollars and I'm glad my $50 offer for another A1097 was rejected.

[Nurbog]

Re: Apple Cinema HD Display LCD 23" (A1082) with 24V power supply (A1097)

Sorry for coming up with this old thread but it seems you have a fairly large solder joint in the upper left corner of the pcb-bottom-picture?

Well, I just stumbled across because I have a A1097 which outputs only 20V. I changed the 20nF cap but everything else seems fine. unsoldered all caps, did a measure and everything works.

Did you ever get your PSU to work? May you know the source of the problem?
Or do you have any type of circuit diagram for this PSU?

Thanks in advance!

[Chungalin]

Re: Apple Cinema HD Display LCD 23" (A1082) with 24V power supply (A1097)

Fact 1: it has lasted more than 3 years.
Fact 2: it’s here again with similar symptoms.
Fact 3: 22nF cap that I replaced 3 years ago and I stated it was the cause, I checked it months later (I searched it in the bad components bin) and it had good capacity, so I think (like budm) that I fixed it by accident.

Today I’ve ressoldered all "4424" (4.42MΩ) SMD resistors and it works again. It happens that some of these high value resistors are very cose to primary caps, and that’s where I worked years ago.