Late '08 Blank Screen Problem

[pdechavez]

Hi guys,

My laptop screen stopped showing visuals (No apple logo on boot, OS, etc.) but the backlight works. The laptop is fully functional. I can hear my applications starting up but the screen just stays black. I can use my laptop if I plug in an external display via Mini Display to HDMI adapter.

Here's what I've done so far:
- Opened the laptop to check for loose cable connections.
- Using the external display, I opened "System Reports" and verify that the built-in display is detected.

Background of laptop:
- The laptop fell a year ago which cracked the plexiglass and the black clutch hinge.
- A few months after the drop, the wifi card stopped working.
- The battery also expanded.

I bought replacements for the plexiglass, hinge, wifi card, and the battery. Installed them without problems and the laptop looks new. The laptop ran fine til a few days ago when the screen stopped working.

Any advice is appreciated.

Thanks

 

[simsaladimbamba]

What shows up in System Preferences > Displays > Arrangement? Is the MBP's screen recognised or is it set to MIRROR DISPLAYS?

 

[pdechavez]

What shows up in System Preferences > Displays > Arrangement? Is the MBP's screen recognised or is it set to MIRROR DISPLAYS?

Thanks for the quick reply. I currently have my external display as Mirror Display as I cannot see my primary screen. As I mentioned earlier, I can use my laptop If I plug the external screen. This means that I cannot see anything (other than the backlight of the LCD) on my laptop's built-in screen.

I also noticed that my wifi card isn't being detected.

 

[simsaladimbamba]

Thanks for the quick reply. I currently have my external display as Mirror Display as I cannot see my primary screen. As I mentioned earlier, I can use my laptop If I plug the external screen. This means that I cannot see anything (other than the backlight of the LCD) on my laptop's built-in screen.

I also noticed that my wifi card isn't being detected.

I had that same MacBook Pro, and a friend of mine has it too. What I experienced was, that when the integrated graphics processor (IGP) (9400M) was in use, that the screen would go black for a fraction of a second every couple of minutes or so. It happened on my MBP and still happens on the friend's MBP.
But when the dedicated GPU (9600M GT) is in use, the problem has gone away.

Do you know, which GPU is in use, maybe via System Report > Graphics / Displays or gfxCardStatus? And if it is using the IGP (I am currently using the 9400M with my 2009 MBP and an external display, though in Clamshell mode), can you switch to the dedicated GPU and see, if that makes a difference?

 

[pdechavez]

I had that same MacBook Pro, and a friend of mine has it too. What I experienced was, that when the integrated graphics processor (IGP) (9400M) was in use, that the screen would go black for a fraction of a second every couple of minutes or so. It happened on my MBP and still happens on the friend's MBP.
But when the dedicated GPU (9600M GT) is in use, the problem has gone away.

Do you know, which GPU is in use, maybe via System Report > Graphics / Displays or gfxCardStatus? And if it is using the IGP (I am currently using the 9400M with my 2009 MBP and an external display, though in Clamshell mode), can you switch to the dedicated GPU and see, if that makes a difference?

I sometimes experience the flickering, however, that's not the problem I am currently facing. It still wouldn't make a difference regardless of which GPU I enable (9400M or 9600GT).

 

[simsaladimbamba]

I sometimes experience the flickering, however, that's not the problem I am currently facing. It still wouldn't make a difference regardless of which GPU I enable (9400M or 9600GT).

Was just a thought. I am now out of ideas, except, that you could try a PRAM reset, but other than that, I am not thinking of it.

 

[pdechavez]

Was just a thought. I am now out of ideas, except, that you could try a PRAM reset, but other than that, I am not thinking of it.

Already tried the PRAM reset..no go! Thanks for your input though.

I have a feeling it has something to do with the LVDS Cable. Maybe a loose connection from the lcd end. However, I can still set the backlight brightness which is odd. Unless the backlight isn't controlled by the LVDS cable.

Will work tomorrow on removing the plexiglass and checking the lcd.

Any other input would be appreciated.

Thanks