iMac CRT Transplant -- Mission Impossible?

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davintosh's picture
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iMac CRT Transplant -- Mission Impossible?

Ok, here's the scoop; I've got two iMacs with problems, and I'm wondering if I can scavenge parts from one to get the other back in action. One is a Bondi Blue 233MHz tray loader with a bad analog board or power supply (it will start and run, but will shut down intermittently and without warning,) and the other is a blue 350MHz slot-loader with a dying CRT -- so dim you have to shut all room lights off just to see what's on it.

I was thinking of hacking the blue 350 to put an LCD in it or something, but then the Bondi machine came up, and it got me thinking. I know the Bondi's CRT is getting old and may not last too long, but if it's just a matter of moving it to another machine and hooking up a few wires, it might be worth it. If it's more difficult than that... well, I'll just move along.

Anybody have any ideas on this? Thanks!

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as always - be careful of vol

as always - be careful of voltage. 2nd - if you do everything right it might work. Good luck.

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Twiddle with the brighness se

Twiddle with the brighness setting on the bondi. Its crt wont fit in the rev A

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Re: Twiddling

Actually, its the 350 that has the dim CRT. The brightness and contrast are at max, and its still too dark. I was told by an Apple tech that there is an adjustment inside that might give it some more life, but it'd cost $60 to get it done at the service center.

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This adjustment is actually v

This adjustment is actually very easy to do yourself. Just remove the bottom plastic. Then on the left side (I believe) you will see two black dials. Use a flat head to adjust them to your liking. Just did this last week for the same issue. Takes 15min.

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But...

won't the CRT continue to degrade, and eventually become too dark to overcome with that adjustment? I'll give it a try, but the Apple tech I spoke with said it's basically a bandaid to keep it usable for a little while.

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I ment the internal adjuster.

I ment the internal adjuster...

And please use an insulated screwdriver!!!!

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It really depends on the seve

It really depends on the severity of the issue. Sometimes you can adjust this and not have a problem, and sometimes it is just temporary.

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no, dont use an insulated scr

no, dont use an insulated screwdriver. solder a normal poer cable to the ground on the nearest electric socket.

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Well...

I pulled the bottom case off last night & twiddled with the screen controls, and was able to get a usable image on the screen, but there are some nasty artifacts along with it... Anything other than the solid desktop background shows a shadow to the right, fading a bit the farther it goes. I know next to zilch about monitor diagnostics; is this a sign that the CRT is failing, or is it something in the analog board?

Just for the record, I did use an insulated screwdriver, but the adjuster slot and pot is made of black plastic; little chance of contacting dangerous voltages as long as I exercised some care in making the adjustment. I would think that one only needs to be careful to stick the screwdriver into the adjuster slot first, then watch what happens on the screen, making sure that if the screwdriver comes out that you look when sticking it back in. Trying to get it in the proper place without looking would be a Very Bad Thing.

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Earthing

Um, making sure of course that the earth line is the only one you connect to, or even has a *chance* of making contact - either strip off and seal the other two lines well clear of the screwdriver, or snip off the pins on the plug. Preferably both.

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Re: no, dont use an insulated scr

no, dont use an insulated screwdriver. solder a normal poer cable to the ground on the nearest electric socket.

Are you a completly mad??

So ok, he uses a non insulated screwdriver to adjust the pots and slips, making contact with the high voltage flyback. Nice one!!

Anyway, some of the components are isolated from earth ground...so an earthed screwdriver is going to do sod all if some part of his body is in contact with the case ground of the monitor.

Insulated screwdriver is definatly recommend unless your suicidal.

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TL CRT - SL

Actually as far as I now know, the CRT in the slot-loaders is substantially more curved than the trayloaders', and has a shorter/differently-shaped neck.

I doubt that you could easily perform such a transplant, should it become necessary.

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working around high voltages

A good rule while working on gear with high voltages, always keep one hand behind your back. That way you can't get a lethal shock across the torso between the hands. Touching a hi V component with just one hand may give a nasty shock but is unlikely to kill you the way the same jolt likely would if it passed through your heart.

dan k

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have you tried a good calibra

have you tried a good calibration? that sometimes turns a suspected dead screen to a working one. seen it happen.. too few people properly calibrate crt's.

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Re: Calibration

What is involved in this "calibration"? You don't mean the ColorSync calibration in the Monitors CP, do you?

I do have access to a Gretag spectrophotometer and a professional monitor calibrator; do you think that would that do the trick?

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