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reddrag0n
Jul 27, 2011, 09:58 PM
I was wondering if anyone could tell me what my poor iMac is doing.

I bought it off of Kijiji and when it was demo'd before i bought it, it was working fine. Once i got it home and turned it on, i got this on my screen...

http://dl.dropbox.com/u/1020076/imac/IMG_0004.JPG

I turned it off, let it sit overnight, and then turned it on again. This time instead of those lines, it fades from black to green then to a bright white.

I am able to turn up and down the brightness via the keyboard *F14 and F15 keys* but that's all i can do. I don't see anything on the screen other than bright white.

Is this a problem with the onboard graphics, or is it something else?



btbrossard
Jul 27, 2011, 11:00 PM
Can you hook up an external monitor to the mini vga port?

Most likely, the on board video is bad, but hooking up an external monitor will confirm that for you (and rule out just a bad lcd display/video cable/ect).

KurtangleTN
Jul 27, 2011, 11:01 PM
Is it possible to test it on an external monitor? That way if it displays fine on the external monitor it's most likely a loose connector or possibly the LCD itself.

If it doesn't display ok then it's graphic card related.

Edit - Beat by a minute..

reddrag0n
Jul 27, 2011, 11:04 PM
Sure, if you can loan me an adapter to test that theory. since all the stores here in Edmonton don't carry the mini-vga to vga adapter.

Nameci
Jul 27, 2011, 11:17 PM
could be the lvds cable... imo.

Intell
Jul 27, 2011, 11:18 PM
could be the lvds cable... imo.

A test of this is to move the screen around when its on. Do the images change when the screen is moved?

Jethryn Freyman
Jul 27, 2011, 11:22 PM
Can't really say either way here...

You'd really need to find a mini VGA adapter to hook up an external display.

reddrag0n
Jul 28, 2011, 12:23 AM
Intell: As for moving the screen, yes, tilted it, moved it up and down, almost broke the neck because i moved it around so much, and no, still the same issue

Nameci: Would that be the cable labeled TMDS?

Intell
Jul 28, 2011, 07:16 AM
Intell: As for moving the screen, yes, tilted it, moved it up and down, almost broke the neck because i moved it around so much, and no, still the same issue

Nameci: Would that be the cable labeled TMDS?

Yes, the internal video cable on G4 iMacs is called the TMDS cable. If the on screen images didn't change, then that cable probably isn't to blame.

reddrag0n
Jul 28, 2011, 01:37 PM
I have read on some of the apple forums that the inverter board might be to blame, but it still has brightness control. I have ripped apart the lcd unit and found 4 cables that connect to the inner area.
1 - TMDS cable, 2 - the mic cable, 3 - the power light cable, 4 - both inverter power cables. I double checked all of those and still no change. So far it's boiling down to one thing, the logicboard. If i replace this, can i also go a step up in cpu speed too? Am not sure if the 700 and 800 MHz models were identical for those years.

Intell
Jul 28, 2011, 02:55 PM
I have read on some of the apple forums that the inverter board might be to blame, but it still has brightness control. I have ripped apart the lcd unit and found 4 cables that connect to the inner area.
1 - TMDS cable, 2 - the mic cable, 3 - the power light cable, 4 - both inverter power cables. I double checked all of those and still no change. So far it's boiling down to one thing, the logicboard. If i replace this, can i also go a step up in cpu speed too? Am not sure if the 700 and 800 MHz models were identical for those years.

The 700 and 800Mhz boards are the same, but are different from the 1 and 1.25Ghz boards.

reddrag0n
Jul 28, 2011, 05:51 PM
Ok, so i can easily get an 800 MHz iMac G4 board with the onboard Geforce 2 MX graphics. That's good to hear.

I just restarted the iMac and the same thing with the display is happening again. The fading from black to green then to a bright white.

I will post a few videos showing that it works, but not the screen.

reddrag0n
Jul 28, 2011, 06:06 PM
Here are a couple of videos showing what the iMac does when it boots up.

The screen doing it's fading trick (http://www.youtube.com/watch?v=8ovk-FCunSo)

The iMac showing that it can lighten and darken the screen and sounds showing it's on and recognizing commands. (http://www.youtube.com/watch?v=evb-JkCip-g)

reddrag0n
Jul 28, 2011, 10:28 PM
Well, the iMac is running, updated to the latest 10.4.11 via VNC and now this is what i am seeing on the screen. It looks like girl stripes!!!

http://dl.dropbox.com/u/1020076/imac/IMG_0008.JPG

Yeah, i think the graphics chip has given up the ghost

btbrossard
Jul 28, 2011, 11:13 PM
It's pretty...

Intell
Jul 28, 2011, 11:15 PM
Well, the iMac is running, updated to the latest 10.4.11 via VNC and now this is what i am seeing on the screen. It looks like girl stripes!!!

Yeah, i think the graphics chip has given up the ghost

It's pretty...

Trippy. If you can get that to move, I can get you to groove...