Toshiba Satellite L455D-S5976 no display

[GoneGault]

I dont know the history on this laptop. It appears clean, including the fan and fan exhaust. When you plug it up, the power led comes on. When you push the on button, the 'on' led lights, but there is no display. The fan spins for 3 seconds and it then cycles on and off just as if the laptop is running normally. There is also no video when plugged into an external monitor. I have removed and replaced the ram, removed the battery, removed the wifi card, and removed the hard drive. No change in behavior.
It came equipped with Windows 7 and a 2.1 GHz AMD Sempron and a 'Radeon 3100 Graphics Coprocessor'.
My best guess before opening it is that the gpu is bad. Any input?

[dj_ricoh]

Re: Toshiba Satellite L455D-S5976 no display

try a soft reflow, but i`m 80% sure that its not the gpu.
take the cpu out and see if it does the same

[GoneGault]

Re: Toshiba Satellite L455D-S5976 no display

I have now opened the beast and removed the motherboard. When plugged up, the 'plugged up' light comes on, when powered on, the 'power on' light comes on but it has no video output. I include a motherboard schematic and pictures of the mb. I hope someone will give me some test ideas or repair suggestions. Thanks!

[spleenharvester]

Re: Toshiba Satellite L455D-S5976 no display

Likely a dead GPU. I've seen many RS780M and similar GPUs from this generation die.

Try a reflow.

[RJARRRPCGP]

Re: Toshiba Satellite L455D-S5976 no display

The CPU may have failed due to overheating. (Like an HP Athlon II rig I worked on that would shutdown and Windows 7 BSOD'ed once on me.)
(BSOD unexpected, because it wasn't overclocked!)

Just to get normal temps, I had to use a pad to lift the laptop up and use the USB-powered fans on the cooling pad.

Looks a lot like a fundamental cooling flaw with AMD-based laptops, especially pre-2011 or pre-2012.