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Author Topic: iMac G3 CRT rays misalignment  (Read 5357 times)

Valet2

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iMac G3 CRT rays misalignment
« on: December 11, 2017, 12:34:32 AM »

Hey! Got my G3, disassembled it to a single bolt, washed everything and assembled back again.

The CRT image quality it baaad. Looks like the RGB rays scanning is wrong. I've been told that there might be a service menu to tune them, other people say the ring magnets is the way to go, but I might make it worse.

So what do you say? Btw, the washing was not the reason of this issue.
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Astroman

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Re: iMac G3 CRT rays misalignment
« Reply #1 on: December 11, 2017, 04:10:09 AM »

yes, the beams are misaligned/unfocussed...
There is no software adjustment, it's a manual procedure under life threatening conditions.

I only remember it vaguely because it's been such a long time, but iirc a proper adjustment of high quality tubes was practically impossible without dedicated gear.
We (in service department) always returned such tubes to the manufacturer.

You may have some experience in this domain, as you already took the risk of putting a literal hand grenade on the table...
Please provide some information about your personal background. ;)
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Valet2

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Re: iMac G3 CRT rays misalignment
« Reply #2 on: October 17, 2018, 10:48:14 AM »

Forgot to reply.

I've fixed it. Just googled how to do ray alignment properly, rotated pairs of magnetic rings on the tube to make the picture look sharp on the center. It's still a bit out of focus near the corners, but that's ok for me.
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IIO

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Re: iMac G3 CRT rays misalignment
« Reply #3 on: October 17, 2018, 02:52:28 PM »

careful with CRTs. there can still be high voltage hours after unplugging.
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refinery

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Re: iMac G3 CRT rays misalignment
« Reply #4 on: October 17, 2018, 04:51:12 PM »

years ago I had one of those Apple 1710AV monitors and had to do this. what a frickin' nightmare that was. and those monitors were crap.
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got my mind on my scsi and my scsi on my mind

darthnVader

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Re: iMac G3 CRT rays misalignment
« Reply #5 on: October 17, 2018, 05:01:00 PM »

Don't get bit by a flyback inverter. -afro-

Always discharge them to ground when fooling with CRTs.
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