How does one determine what is causing white screen?
As Shipped Unit Description:
- Serial Number: W87130ZKVGN
- Type: iMac "Core 2 Duo" 2.16 24-Inch (T7400)
- Intro.: September 6, 2006
- Disc.: August 7, 2007
- Order: MA456LL
- Model: A1200 (EMC 2111)
- Family: Late 2006 - 24"
- ID: iMac6,1
- RAM: 1 GB
- VRAM: 128 MB
- Storage: 250 GB (7200 RPM)
- Optical: 8X DL "SuperDrive"
Question
System boots to the point that it shows a white screen with a cursor that can still be moved (ie. not frozen). Need to determine what needs to be repaired to put the unit back in service? Can't be sure whether it is a board failure or not.
What I've tried
Tried booting off CD and can get access to see choice of boot drives, can see verbose startup, and can see drive contents. Booting of internal drive results in a white screen with a movable cursor no matter what key combinations or cache clearing "tricks" are tried. Disassembled unit and connections appear OK. Have not been able to figure out how to remove "back" to check other side of logic board, but caps on power supply appear fine.
Additional details of things tried
- Hard drive itself seems to be functional, based on checks after booting from CD.
- Makes all the right noises on startup before the apple and spinning gear.
- Holding down option key on startup works ok. Shows the partitions on the hard disk.
- Holding down shift key on startup doesn't work. Goes into white screen and stays there (but shows movable cursor).
- Holding down D key on startup doesn't work. Goes into white screen and stays there (but shows movable cursor).
- Holding down command V (verbose mode) doesn't seem to work.
- Resetting SMC, PRAM, safe mode doesn't work.
- Prior to failure didn't give any indication that video card was failing. I.e. no lines, no break up or distortion of images.
Questa è una buona domanda?
2 Commenti
Pulled the hard-drive cable and verified that I got a file folder with a flashing "?". Then tried booting off an original Leopard install disk. The "boot" progressed to a blue screen with an active pointer cursor. That is as far as it went. Given that a similar machine without a hard drive went all the way to the install menu, it appears that the hard drive is not the problem.
Can someone provide an idea what I can try next? A graphics card is out of the question. The machine is not worth the investment, but maybe the problem is something easier to fix. Not sure how to tell for sure.
da Gary Gauthier
IMPORTANT:
Found the original disks for the system and was able to run the extended version of the diagnostics several times. It says "No trouble found". Not sure what this tests, if anything, beyond the explicitly stated memory and logic board. Does not seem to "test" graphics, but it does use them in the diagnostics program.
I should note that the diagnostic program shows 2GB installed, not 1GB as originally posted. Have verified this is correct by inspection of the memory installed. The video card is an NVIDIA GeForce 7300 GT w/128MB VRAM.
Next, I tried booting off the original install disk. I got as far as the system displaying a message to shutdown and restart the computer. Presume this is a "Kernel Panic", but am not sure at the moment what I can try next.
da Gary Gauthier