I have been called in for a failure in my brother's notebook, a Packard Bell TK85.
This notebook has a P6100 + a GPU Ati Mobility Radeon HD5470 with 512 MB dedicated RAM.
The notebook has some earlier small issues, in that every so often (once or twice in a month) it crashed with a blue screen, windows had to be restarted and was coming up with a message like: 'graphics drivers restored'. The system restarted working regularly, so no particular notice was taken of this.
Two days ago the laptop crashed again, but this time restarting the video would not come up. After a few attempts restarting it, the video come in and Windows loaded, but the mouse was not responding, so a new restart was done. Since the the notebook screen has remained totally black. I was called in and this is what I did:
a) I hooked up a VGA monitor and have seen that the video signal COMES OUT correctly.
b) Windows failed to load in normal mode, as it would stumble always in a blue screen with an error in atikmpag.sys
c) Windows started in safe mode. I attempted a recovery of the earlier situation from the Packard Bell 'recovery' partition. The recovery lasted an entire night and failed to complete...
d) I reinstalled windows (still connected only on the VGA port) and everything seems ok except the video. When I install the Radeon drivers (tested both the older one from the PB TK85 site and the newest ones) Windows fails to load in normal mode with the same blue screen. Have then to go to safe mode and remove the ATI drivers (and then windows loads ok).
e) I have reflashed the pb tk85 BIOS. No change apparently.
e) I have dismantled the notebook and checked for loose cables, signs of shorts etc. Nothing noticeable. I tested the inverter and it works. I tested the screen lamp (with a video signal from a different laptop) and it works.
The problem had to lay in the video card/signal then.
I am now a bit lost, as I feel it might be a failure in the ATI HD5470 or even the vga BIOS.
BUt why does the video signal work on the VGA port (external monitor)? This is now detected by benchmark programs as 16MB card.. Why is this?
Can anyone suggest what can I do to have the video signal back to the laptop screen? Is it possible to reflash somehow the ATI VGA BIOS? How (ATIWINFLASH tells me the ROM cannot be read)...