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Do I need to replace an inverter or backlight

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14 replies to this topic

#1
ceez

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Hello everyone, I have a toshiba laptop that starts up the toshiba post screen with a pink hue and then goes black when it leaves the post. you can hear windows vista start up but there's nothing on the screen.

I tried attaching an lcd to the vga out but didnt get any display no matter manny times I pressed the Fn+f# key to switch between laptop screen and external video.

so I've read that if it goes black then it's the backlight, but that if it's pink-hue then it's the inverter....then i've read the opposite. I am going for the backlight since i am thinking the light doesnt have enough juice to light up the high graphics pass the post.

what do you guys think?


thanks for the help.

Ceez
ceez


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#2
cluberti

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Usually if you can see the POST (no matter how ugly) and then nothing, especially if the display is "sleeping" as a Dell of mine did last year, the graphics chip itself is potentially bad. Just be aware of this especially given that you claim a pink hue and then nothing - that wouldn't happen to have a GeForce Go chip in it, would it?

The good news is you can usually get a replacement inverter or CCFL for a few dollars, and they're both usually field-serviceable parts. The bad news is that they're both somewhat non-trivial to get at in some Toshiba laptop models where they're housed behind the LCD. The other bad news is replacing them isn't likely to fix it, but given it's only a few dollars to try I'd suggest it anyway just to be sure.

Usually inverters go bad either due to poor craftsmanship (possible, but not likely) or they're overworked or overheated. In general, if the CCFL is drawing too much current (gone bad) and overheats the inverter, you'll get no display at all - which is a similar symptom, but that usually happens immediately on power-up, not *after* the POST (a bad inverter usually gives you only a split second of video, and then it goes away). Next, if a CCFL has *started* to go bad, you generally get a pink tint, but it either stays that way or goes away slowly as the unit runs - again, similar symptoms, but you'd notice over time that the display would dim on half or all of the screen, you'd get a pinkish or reddish tint to everything for some time, and *then* it'd go bad and you'd get nothing (no POST display either, most times). The fact you get a pinkish post and then zero output as the display is switched from the BIOS resolution to the kernel (and thus the video driver) would not really be something I see with a dead CCFL or inverter, so either you have some loose wiring (again, possible but not likely unless the display comes back with some jiggling of the screen or laptop) or a bad GPU on the motherboard itself. Again, the actual point of failure, the pinkish/reddish tint during POST, and the fact that the external display doesn't respond to the keyboard display changes would lead me to expect you'll have a bad GPU, not a bad LCD or CCFL/inverter.
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#3
jaclaz

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What do you guys think?


Boot the laptop.
Open it up completely (so that both keyoard and screen are flat on the desk.
Switch room light OFF.
Get a torch and try putting it at an angle around 5 to 15 degrees to the screen.
If you can see a graphic element (like the taskbar, or an icon, or something (I do hope you do not have a completely blank desktop) it's the backlight OR the inverter (if I really had to, I would vote for the inverter :unsure:), BUT if you can see nothing and the external VGA doesn't work it may well be the graphical card/GPU :ph34r:, and in most laptops it is integrated on the motherboard. :(

It is essential that you check, re-check and triple check that you are using the right key combination to get the external VGA working (if it does) otherwise you will anyway waste the money for the backlight or the inverter.
Poorman's testing:
http://www.laptoprep...klight-failure/
http://www.laptoprep...rter-in-laptop/
http://www.fonerbooks.com/test.htm
http://www.fonerbooks.com/laptop14.htm

Don't forget to check for the "fourth" option: simply the little switch that turns off the LCD when you close the laptop, some contact cleaning spray may do the miracle. ;)

Stupid as it seems, see if you can boot some kind of DOS on the laptop, I've seen some screens that do work if no driver for higher resolution is loaded.

jaclaz

#4
ceez

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this is why i love this forum....such professional and smart advice!

thank you both, I will check out all the options given.

if it's the onboard video then i guess it's time to recycle the laptop.


THANKS AGAIN!

ceez
:thumbup
ceez

#5
ceez

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another finding:

when i first turn it on I am able to get to the bios screen but roughly for less than 10 seconds before the screen goes black, I ctrl-alt-del, see the post, press F2 and repeat the process. After about 5 times I was not able to see the bios screen and only the post. Does this lean more towards a backlight overheating or maybe just going bad and cant stay on after a few mins of use?

i am just trying to prevent having to buy a backlight AND an inverter.

thanks!
ceez

#6
cluberti

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Is the BIOS screen pinkish? Like I mentioned above, replacing the CCFL and inverter are usually cheap and don't take too long, so doing so is always a good troubleshooting step. However, I would still say that something like that happening so quickly would indicate a GPU failure, but you could get lucky and have it just be an overheating inverter due to a bum CCFL.
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#7
ceez

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ok another update....

I was connecting the video cable to the laptop using our kvm... earlier i didnt notice that the light on the kvm would power off after a few seconds when initially i looked at it and it was on (the light that shows the # of the kvm that's connected and active).

I immediately felt dumb....connected DIRECTLY from laptop to lcd and I have perfect video and can boot successfully and there are no video problems at all. While connected to the lcd I also noticed a very-very faint display on the laptop screen and then it was gone.

So now I am pretty sure that it's the backlight.

I will place the order and replace!

thanks a million
ceez

#8
puntoMX

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So now I am pretty sure that it's the backlight.

I will place the order and replace!

They are cheap, some 8USD shipped from China, do you know the model name and part number?

#9
ceez

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PMX I found some of those cheap 8-10 dollar ones but they dont come with the cables or the connector to the inverter. but i found one for 59 bucks with the cable/connection. but this is not for me it's for a customer so i am good.
ceez

#10
puntoMX

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PMX I found some of those cheap 8-10 dollar ones but they dont come with the cables or the connector to the inverter. but i found one for 59 bucks with the cable/connection. but this is not for me it's for a customer so i am good.

I would go safe there too indeed.

#11
cluberti

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Please remember that a failing GPU doesn't necessarily mean output to an external device won't work - I've seen it with my own eyes. Let us know how the replacement goes though - hopefully you'll get lucky!
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#12
jaclaz

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Please remember that a failing GPU doesn't necessarily mean output to an external device won't work - I've seen it with my own eyes. Let us know how the replacement goes though - hopefully you'll get lucky!

Yep, but still it is "negative evidence" (or a hint towards further testing) :).

I.e.
  • IF no screen is seen on external VGA the probabilities of a failing video card/GPU is very high
  • IF a screen is seen normally on external VGA the probabilities of a failing GPU for the internal display only is fairly low

jaclaz

#13
ceez

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Please remember that a failing GPU doesn't necessarily mean output to an external device won't work - I've seen it with my own eyes. Let us know how the replacement goes though - hopefully you'll get lucky!

Yep, but still it is "negative evidence" (or a hint towards further testing) :).

I.e.
  • IF no screen is seen on external VGA the probabilities of a failing video card/GPU is very high
  • IF a screen is seen normally on external VGA the probabilities of a failing GPU for the internal display only is fairly low

jaclaz


that is my same experience when calling DELL support for their crappy laptop with bad lcd screen. the first thing they ask is "did you test with an external monitor"? 99.9% it fails and they send in a new mobo.


@puntoMX, the toshiba is a satellite A135-S4527, do you know a good website to find one? I just googled the name of the company I ordered it from and they have extremely BAD reviews, give it a try, it's pelltechnology. considering they havent replied to an email 3 days old I decided to stop payment before they even attempt a charge....but that's another post.

so now i am off to scramble for a new backlight with connections.
ceez

#14
jaclaz

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that is my same experience when calling DELL support for their crappy laptop with bad lcd screen. the first thing they ask is "did you test with an external monitor"? 99.9% it fails and they send in a new mobo.


Yep :), question now is "can jaclaz's tip be compared to DELL support"?

Or is it just a one-time coincidence that the DELL guys are right? :angel

;)

:lol:

jaclaz

#15
puntoMX

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@puntoMX, the toshiba is a satellite A135-S4527, do you know a good website to find one? I just googled the name of the company I ordered it from and they have extremely BAD reviews, give it a try, it's pelltechnology. considering they havent replied to an email 3 days old I decided to stop payment before they even attempt a charge....but that's another post.

Is this just the inverter or the FTL/CCFL too?

I changed p*to in punto; it has been a while ago that I sold my body to women so to say. ;)

Yep :), question now is "can jaclaz's tip be compared to DELL support"?

No... It will take yeas for Dell to get their people tip at the same level.:lol: "Now, let us see what the knowledge base has to say...". Really, they don't need smart people, just the ones that can skip and ditch the "customer" (consumer) withing 10 minutes... Tops!.

Just simple Q and A...




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