iMac G3 - Display Issues ??

Hi everyone,

Been round macs for years, got 2 imac g3 500s at home (among various other macs ) and one of them at the moment is used as a spare machine for basic stuff.

anyway, just recently the display is black on boot and it will start up but no display at all. So i reset the logic board and ..... chime, everything works perfectly.

problem is that every reboot the display is dead again and i have to reset the board. I think it is the flyback transformer (on the analogue board) but im going off another g3 i mac i had a few years back which died because of that. This one seems different because a reset gets it up and running and also there are no burnt out smells or popping sounds coming from the CRT. The computer is also in a well ventilated area.

I know this model is 11 years old but still works fine and am amazed it runs so well for its age. BTW running 10.4.10 on it with 1G ram.

Thanks, any input is appreciated.

Could be a problem with the CRT or some of the hardware associated with it (either the flyback transformer as you mentioned, or another part of either the input or power supply circuits), but honestly, I don't think it is, for one reason:
From what I gather from your post, the issue is consistently fixable by resetting the pram (I assume that's what you mean by resetting the board).

Based on that conclusion, I'd suggest replacing the pram battery first (it's a long shot, but the batteries are cheap). If that doesn't work, my first suspect would be a dying logic board.

I agree with what Geeky1 said. On the Flyback issue, I doubt it since it would always be acting up. The very old TRAY loading iMacs were the ones that blew Flybacks due to heat and breakdown in the windings over time. My 333Mhz Tray Load started snapping and then went all the way and Popped and sparked. Flyback. New one and it's as good as new again. They say that the Slot Load models did really not suffer with the Flyback issue, but anything can happen. Does it work fine once you get the display to come on after the PRAM reset?

It could be the PRAM battery. Do check that in case. Geeky gave some good info.

yeah good idea, ill give the battery a check.

I should have made myself clearer though, i mean resetting the LB as actually pressing the button (located near the ram slots, or thereabouts) for one full second and then the screen works like a charm. I restarted once while it was working and it started fine the screen came on. But when you leave it for a while shutdown it wont come on.

It does seem weird but yeah ive gotta turn it over and reset everytime and yes it is a slot load.

I hope its the battery...