Screen Problems with iMac G5 20" (iSight)

Question

Hello!
I had the same problem with my iMac G5 20" (iSight) as described by Bob North Apr. 18, 2006 at http://www.macintouch.com/readerreports/imacg5/topic2276.html#apr25:
"""" I repair Apple products, and recently I've seen strange and erratic display problems with the G5 flat-panel (iSight) 17" and 20"...and I am very curious about the origin. The picture will display what I will call "plaid pixles". Upon boot, the dispaly appears normal, but within 5-10 minutes, either at desktop or in ASD, the normal display will "crash" to the "plaid" display. The desktop, or whatever, can still be distinguished in the background, but it is overwashed by the plaid patterns -- which do change slightly, and also cover the full space of the screen. I've seen different scenarios, 3 in 2 weeks, where the symptom is exhibited with no particular failure pattern -- both before and after repair. I've replaced the main logic on one occasion, with no fix...but the 2nd try replaced both display panel and inverter. The display issue was fixed, but the system exhibited lockups only when it reached the destop. Another repair the same issue was seen after replacing the 20" main logic, where the symptom was not present previous. Personal opinion of the late 2005 IMAC flat-panels, in the hardware sense, is the likelihood of component manufacture issues, possibly the main logic boards or the panel displays themselves. Repair of this model, as opposed to the earlier, non-iSight flat-panel 17 and 20" models are extremely difficult -- access to main componenets is blocked by the display panel, which must be removed for each troubleshooting attempt. The internal hardware design is not oriented for repair ease...they are by far the most difficult to work on.
Any input regarding the display issues? Thanks.""""
I can't use the mouse or anything else, and after a while the fans start to go on max. This is the second time I encounter this problem within 30 days. What I have noticed is that the day before, the brightness of the screen started to "blink" slightly -- like if the screen tried to adjust itself.
But I haven't experienced what Bob North describes as the: "Upon boot, the dispaly appears normal, but within 5-10 minutes, either at desktop or in ASD, the normal display will "crash" to the "plaid" display".
I just restart with the power button and everything is working OK. I made an Extended Hardware test without any problems detected.
I have been looking for this issue with iMac G5 20" (iSight) and only found it at http://www.macintouch.com/readerreports/imacg5/topic2276.html#apr25 :
Apr. 18, 2006
bob north
I repair Apple products, and recently I've seen strange and erratic display problems with the G5 flat-panel (iSight) 17" and 20"...and I am very curious about the origin. The picture will display what I will call "plaid pixles". Upon boot, the dispaly appears normal, but within 5-10 minutes, either at desktop or in ASD, the normal display will "crash" to the "plaid" display. The desktop, or whatever, can still be distinguished in the background, but it is overwashed by the plaid patterns -- which do change slightly, and also cover the full space of the screen. I've seen different scenarios, 3 in 2 weeks, where the symptom is exhibited with no particular failure pattern -- both before and after repair. I've replaced the main logic on one occasion, with no fix...but the 2nd try replaced both display panel and inverter. The display issue was fixed, but the system exhibited lockups only when it reached the destop. Another repair the same issue was seen after replacing the 20" main logic, where the symptom was not present previous. Personal opinion of the late 2005 IMAC flat-panels, in the hardware sense, is the likelihood of component manufacture issues, possibly the main logic boards or the panel displays themselves. Repair of this model, as opposed to the earlier, non-iSight flat-panel 17 and 20" models are extremely difficult -- access to main componenets is blocked by the display panel, which must be removed for each troubleshooting attempt. The internal hardware design is not oriented for repair ease...they are by far the most difficult to work on.
Any input regarding the display issues? Thanks.
Apr. 19, 2006
Robert Mohns
bob north describes: "...recently I've seen strange and erratic display problems with the G5 flat-panel (iSight) 17" and 20"...and I am very curious about the origin. The picture will display what I will call "plaid pixles". Upon boot, the dispaly appears normal, but within 5-10 minutes, either at desktop or in ASD, the normal display will "crash" to the "plaid" display. The desktop, or whatever, can still be distinguished in the background, but it is overwashed by the plaid patterns -- which do change slightly, and also cover the full space of the screen."
Does it look anything like this?
http://downwardspiral.net/gallery/pbg4-display
My nearly 3 year old Titanium PowerBook G4 just did this one day, out of the blue. The problem went away after a few minutes, but I had already taken photos. Thanks to those photos, Apple gave the powerbook a new logic board.
(This PowerBook has had its logic board replaced twice, a new optical drive, and a cracked case edge replaced. AppleCare has more than paid for itself. Despite the occasional problems, I remain very happy with this machine. I'm sure I'd be much less happy if I had not bought AppleCare!)
Hubert

Answer 1

Hubert Frank,
To Apple Discussions!
What troubleshooting methods have you tried to solve your issue?
The knowledgeable users will need this info to avoid the "been there, done that" senerios.
Have you tried the methods mentioned in the following Knowledge Base Article?
http://docs.info.apple.com/article.html?artnum=301283 Troubleshooting when there's no picture on the display
Do you have AppleCare? If so, have you contacted them? If so, outcome?