Toshiba laptop L300D Black screen - Need Help !!

[RSD99]

Hi,


I have a problem with a Toshiba laptop L300D-10B which does not boot up. When i press the power button, the laptop turns on (power light is on, cd-rom works, fan spins) but HDD light is off and the screen is black-completely off.


Things checked:

1. Power adapter tested with multimeter and looks ok.
2. Power adapter changed with another one.
3. Power is coming ok with no loss up to the motherboard pins. Tested with a multimeter.
4. HDD connected to desktop and works ok.
5. HDD changed with another one from a different laptop which works fine.
6. Removed battery and power cord out of the laptop and then pressed the power button for over 30 sec.
7. RAM removed and reseated one by one.
8. RAM changed with another one from a different laptop which works fine.
9. Disassembled the laptop unplugging everything.
10. CPU unplugged and replugged.
11. New thermal paste was applied on CPU and GPU.
12. Fan and heatsink were cleaned from dust.
13. CMOS battery tested with a multimeter and looks ok. (3.3 V)
14. CMOS battery removed for a few minutes and resoldered.
15. CPU changed with another one the same from a working laptop.
16. A new monitor connected on the vga port. (Still black)

I don't know what else to do. I'm afraid that the fault is on the motherboard or the GPU. If you have any advise to give me, i would really appreciate it.


Thank you in advance.

 

[carnageX]

If there's no display at all, even with an external monitor hooked up, then I'd say it's either the board or GPU.

 

[RSD99]

Thanks for your quick response.