Laptop screen does not turn on

hey i have a toshiba p35-s6112 and it turns on fine but the lcd screen dose not turn on it just stays black. I have tried raising the screen brightness cause i thought it may have been changed that did not work. I also connected a monitor to the laptop and it did work so i think the video card is fine how can i tell if it is the lcd screen or the inverter thanks.

A clue would be, if the Inverter goes, you can usually see a very faint screen (external monitor unplugged)
You may need to pull it apart (electrostatic and power precautions from your manual advised) and visually check the Inverter Board, also reconnect all connections. (one to the inverter, and one, usually behind the screen)

Sometimes you may be able to see the Inverter board "black" and burnt out, just by looking at it.

ok I did all that i check the inverter it lloked fine i also disconnected the cable to the back of the screen and put it back on still black but now when i try to connect the external monitor it does not pick it up

What do you mean? Doesn't the external work now?

Also could you see a very faint display on the laptop screen?

what i meant was now when i connect the cable from my desktop monitor to the laptop it says no signal befor i was able to see my laptop on my monitor that i use for my desktop

no i made sure by testing it in a dark room and there is no signs of light on the laptop lcd screen at all. could it be the screen just died out or also the mobo

If your laptop LCD is fully unplugged, the external will still work
So maybe you should just fully unplug it, and test the external again.

Also the "faint screen" means, it will not emit any light (or very little) so you may need the lights on to view it (if you can see anything)

I'm thinking the LCD connections are not connected properly causing the external not to work.

You shaould also remove the battery and power adaptor, and hold down the ON button for 30secs (to disperse all internal voltage)
Then install the power adaptor again and test.

We at least want the external working, before you look at the Inverter c/o !

ok this is what i did i took the monitor off so i only have the base of the laptop i connected my monitor to it and i still get nothing i also tried pushing fn key and f5 but nothing. I also check for the faint lettering but there is nothing i did all of this after draining the battery by holding the power button as advice.

You mean with the battery out ofcourse, draining the laptops capacitors.

Try re-inserting the ram (or oonly one card, if you have two)
Aso when turning the laptop upsidedown listen for anything rattling inside (like a loose screw!)

Also, obviously unplug any externals.

Here's the "No Post" tutorial: http://www.techspot.com/vb/topic53866.html

It has been a while since anyone posted to this thread...but I am having similar problems

My laptop screen has been having issues. The first time the screen shut off, it flickered a little bit, then all of a sudden the screen turned off. After a couple of manual shut-off, it randomly came back on. I thought it was a one time thing, but it happened about once a week. And my fix would always be to manual shut it off and turning it back on multiple times until the screen came back on.

What usually happens is, I either shut down my laptop or put it on standby, and when I try to put it on, the screen never comes on, but everything else seems to be running. But now, the screen just stopped working altogether. I've tried my 'solution' but it hasn't been working. I tried putting it out to an external monitor, but that doesn't work either. (I have a hp dv2100, the hotkey is fn+f4), I am not sure whether or not I need windows to boot up first before I can use the hotkey or if I can do it immediately after I push the on button. This is an issue for me because I have my laptop on dual-boot with ubuntu.

So since the external doesn't seem to work, I wondering what I should do to fix it. Is it the graphics card/mobo? Is it the inverter? backlight? LCD? I have a lot of experience with taking laptops apart, so replacing a part shouldn't be too bad. I just need some help figuring out which part(s) I need to order/replace.

Thanks

Hey I've written up a whole new "No Post" guide since this thread was made
Tutorial: No POST (Power On System Test)

But it can't be the Inverter board or display if the external monitor doesn't even come on.
Maybe start with the guide

do you happen to know what i have to do with an HP to get it onto the external monitor?

This is what i've tried:
1. taking out the battery and power cord, held the power button for 30 secs. Put the power cord back on, and turn it on.
RESULT: monitor still dark

2. Took out the internal battery (CMOS battery) and waited 20 mins
RESULT: same as #1

3. Reseated the hard drive, and both RAM sticks
RESULT: same as #1

im beginning to think it maybe my mobo do you know of any sure-sign tests? I dont get any beeps of any kind, and my laptop start-up sounds (e.g. harddrive, cd drive checks, and other random sounds) are all the same.

Thanks for the quick reply.

Here's what I'd do
Work out how to dismantle it
Then eventually unplug the screen plug going to the motherboard (ie it's actually not needed ironically)
Plug in an external known working monitor
Plug in the power and turn it on.

Same result? I'd probably continue to dismantle it, until I eventually bench tested the Mobo (all nice and clean too, ie no dust so forth) And if that didn't work, probably decide on replacing the Mobo
Note: This is only after confirming Ram is ok (hard drive a CD drive can just be left out)
I'd probably reseat the CPU as well

unplugged the connector from the display to the mobo and tried a working external monitor: same result

started dismantling everything, cleaned out A LOT of dust balls from the fan/heatsink area. i think something may have burned out because of all the dust, but can't be certain, its just a random guess.

i havent looked under the mobo to see if there is more dust, and i am afraid to take apart the heatsink and cpu cuz ill have to replace the thermal pads.

any other suggestions?

thanks for all the help so far

Yes you will need to repaste the CPU, after you remove\reseat it
Here's some info on that: ArcticSilver Instructions Also use isoprophyl alcohol to clean the CPU first

so conclusions are leading more and more to the mobo...which is also the most expensive...

i am afraid that even after i replace the mobo, it still wont work, but i konw the other parts are fairly cheap compared to the mobo...except for the processor. Is there a chance that the processor could be broken as well?

Thanks

It's a process of elimination
I find the CPU is usually not faulty (I say usually)

Really BenchTesting the Motherboard is the best option (ie Mobo out of the case)
Again this is assuming Ram and all other easy things (connections and things) have been tested

i have everything taken apart right now and im currently reseating the processor, what do u mean benchtesting the mobo??

one more thing, there is currently a padding over the gpu, can i just the that padding off and apply a drop of arctic silver instead??

Well "gpu" is defining Graphics Processor, just a wording issue, but you mean CPU

Anyway, yes clean off the old paste (these are sometimes a perfect square pad)
Benchtesting, well I didn't post the benchtesting link because I only have a PC one
Anyway here's that PC one, that may help in its definition: http://www.techsupportforum.com/1010960-post1.html

the heatsink on my laptop covers both the cpu and the gpu...but on the gpu there is only a soft rubber sticky...so i was wondering if i had to replace that...it doesnt seem like a thermal pad..so i just left it on.

well i reseated the cpu, put it back, just hooked up power, ram, and video out to an external monitor and same result - blank screen

i switched out the ram for known working ram and did the same...blank screen.

i dont have an extra cpu to test, so you said its most likely NOT the cpu, so im guessing its the mobo.

i already cleaned out everything. in terms of cleaniness, the laptop is as good as new.

so i am out of ideas and am thinking about getting a new mobo.

what do u suggest?

Well I don't want to say get a new Mobo, when the smaller chance of the CPU still remains (ie that's your choice )
But that GPU CPU arrangement. Can you upload a picture?