Hello,

I got an old 400Mhz imac (DV Summer Ed.) and brought it home this evening to give to my sister. We had it on the lounge table and were installing 10.2 on it.

My sister went to bed and I shut down the imac and flipped it on it's face to open it's RAM hatch - I have a 256Mb stick and wanted to see if it was of the same type (it's not)

Flipped it back up, turning it on and shit! the screen's gone weird. It looks like this :

Dark blue, not very much brightness, and not very much contrast. The apple logo looks like black on very dark blue.

The screen is smeared or blurred horizontally by a small amount, about 2cm of smearing deflection.

Now obviously in turning it over i've done and knocked something, but i wasn't rough with it!
Has anyone seen imacs do this before?

Thanks

Jeremy

You could try turning it off for the night unplugged and seeing if it's better in the morning. Any magnets in the area? CRT's are affected by magnets and the earths magnetic forces to an extent.

Wouldn't really explain why it's dark.

No (significant) magnets in the area. And before anyone asks, yes I believe it's out of applecare

Will try again in the morning..

Sounds like the EHT circuitry's gone ... the Extreme High Tension stuff generates a huuuuuge voltage that's applied to the front of the CRT that literally pulls the electron beam towards it, so that it hits where it is supposed to go. Without the EHT charge, the electron beam (which is generated in the back of the tube) goes all fuzzy and starts to dissipate.

Either the EHT fly-wire (big chunky thing) from the transformer to the CRT bottle has fallen out, or there was/is a teensy bit of metal inside that has fallen across some part of the EHT circuitry and shorted it.

If it still looks like washed-out crap in the morning, you've just gained yourself some iMac parts ... with some care, you can transplant the guts into a box and make your own server, or something ...


B.

How would you run up a server on a headless imac sans screen? I guess you could do something with it if you could boot it off the network and administrer it remotely. Did old iMacs have the ability to run an external monitor?

Basically if the overnight unplugging doesn't work it's something more serious and I doubt it would be economical to repair unless you really really wanted that machine.
Unless you were really flinging it around I doubt something would have fallen off/out.

This is one of the reasons why all-in-one machines aren't my thing.

Thanks brains,

I have some experience with these things so if I get the inclination I might check it more thoroughly..

iMacs DV have an external VGA port for video mirroring... and yes, you certainly can Remotely Administer the iMac DV

if it's causing this issue still, could you take a photo and show us?

No VGA ports - just Power, Firewire, USB, audio, and ethernet..

When I turned it on this morning I got nothing - the machine booted but the screen was black (or maybe just so dim I couldn't see it in daylight). I rebooted it a few times but to no effect.

I thumped it a bit, tilted it at some angles, and it's started making a HT whine (about 15Khz) which I can hear from a room away. So I think it's a loose wire.

- Jeremy

are you sure it doesnt have VGA?
for the iMac G3's, it was hidden behind a piece of plastic at the back, not near the rest of the ports.

only on DV imacs do they have external VGA

jerra: many models of iMac actually have a standard DVsub15 SVGA connector at the back of the board, allowing you to connect a normal monitor, once you get access to the insides.


B.

Iv had an imac that i tipped on its face that would go coloured etc - leaving it unplugged for a day or so would bring it back

If it is actually a iMac DV with firewire, on the back near the apple logo, down below that there is a plastic cover that comes off to reveal a VGA socket... it's definitely there

and the whining / continual black screen...doubt it's just a cable, that might be the tube dead once and for all..they die like that.

I'd be careful if you were thinking about opening it up, a lottttaaa voltage thru CRT's. Make sure you discharge the CRT properly (black cap on top of the CRT housing)

Like this?

Mine doesn't have it...