Hardware works good but CRT has constant vibration


I've got this iMac (EMC 1857). At start up i get soud and the operating system starts up regoular. I can see images and colours correctly, graphic card, logic board, hard drive and all hardware seem to be ok. The Max resolution 1024x768@75Hz and the geometry function are working properly.

The problem: the crt screen has a constant vibration and there is some sparkling noise from the chassis' back. There is no overheat. You can see the problem on this video: http://www.youtube.com/watch?v=10VSsar9p...

The graphic card works properly: i tried to plug an lcd panel and it works good.

The problem seems to be arount the CRT driver. It is possible to fix it?



I found some information: the reason of the problem could be one (or more) dried filtering capacitors so the 100Hz ripple modulates the electronic beam (or something like...). Flyback circuit seems to be ok!

It seems to be not a strong damage, I think I can solve the problem with tv service.

I'll post the results!

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It is a CRT and they do have a nasty habit of zapping people. I would definitely not suggest that you fix it yourself, but have someone with CRT experience look at the PSU capacitors as well as the fly back transformer. Good Luck


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Outside of opening it and blowing out the dust there's not much you can do. It's had a good long life and it's time to look for a newer one before it dies. If yours has a firewire port your data can be transferred via Target mode. If not get an external backup drive to save your data to.

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