Imac G3 screen resolution?

I recently acquired an imac G3 (graphite), 600 Mhz processor with a stick of 512MB and 128MB of RAM. I am running mac OS 10.3.

Is it normal for the screen to have a lot of flicker at 1024 x 768 resolution? At 800 x 600 it is fine, but at the max resolution it gives me a headache.

I am assuming it is because the refresh only goes up to 75Hz at 1024 x 768. Is there a way to bump of the refresh rate, or am I stuck to using it at 800 x 600?

barryWest said:

Is it normal for the screen to have a lot of flicker at 1024 x 768 resolution?

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No, it's not "normal". I've checked my own iMac 600 to try and replicate what you're experiencing, but it's rock steady.

Is there a way to bump of the refresh rate?

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No, 75 is the only available rate.

Does the flicker problem persist/get worse/get better as the monitor gets hotter?

You could open up the iMac and try the compressed air blow out, the theory being that dust buildup is contributing to the display flicker, but, quite honestly, I suspect that it's simply a CRT 'old-age' issue. The previous owner may never have used 'sleep' to reduce monitor decline.

75Hz is a high enough refresh rate that you should not see any visible flickering, especially that bad its giving you a headache. Sounds like the electron gun in the tube is past its best...

Might be worth opening it up and blasting the internals out with air, although please do so with caution. CRTs run at stupidly high voltages that are lethal. I'm not trying to scare you off, but just don't touch any part of the CRT/Transformer when your in there.

If you want to be that adventurous, leave the computer unplugged completely for 2-3 days minimum for the capacitors to drain.

Like martyp said, CRTs can be lethal.

Is it possible that the power in my house is the problem? I had the machine over at somebody else's house and the screen was perfectly fine at 1024 x 768, no flicker at all. Back to my house, and the flicker was back.

What sort of lighting do you have in the computer room, eg. neon tube, incl the 'power saver' bulbs; and what other devices are operating, eg. central heating or air conditioning (heat pump)? Does your computer room for example share a common wall with the kitchen, where electric power sockets are back-to-back, and where the fridge is in close proximity? Electric motors can play merry scratch with CRT monitors, as can any device with powerful magnets.

Come to think of it, I have had fluorescents wreak havoc on CRTs before. I'd definitely try it in other parts of the house as well.

hughvane said:

What sort of lighting do you have in the computer room, eg. neon tube, incl the 'power saver' bulbs; and what other devices are operating, eg. central heating or air conditioning (heat pump)? Does your computer room for example share a common wall with the kitchen, where electric power sockets are back-to-back, and where the fridge is in close proximity? Electric motors can play merry scratch with CRT monitors, as can any device with powerful magnets.

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Just regular incandescent bulbs in our house. We had an old 17inch crt monitor with our pc up until about a year ago and it had no flicker issues plugged into the same room. I am wondering if the imac monitor is just more sensitive to any fluctuations there might be in the power.
I've seen filtered power bars before, which people use with high end audio equipment to keep the current consistent, maybe one of those is worth a try?

You could try a UPS I guess, it would also act as 'insurance' against a power spike or brown-out. Monitors, like most electronic equipment, have tolerance of drops and peaks, extending sometimes to as much as 70v. Something like the iMac would be more likely in the ∓20-30v, and I doubt you're getting that much fluctuation, and you'd likely notice shimmer in the 800 x 600 resolution as well if you did. Voltage variation is often noticed more in things like fan speed.