Toshiba Satellite L655D Dim display

[ComputerRepairTech]

I primarily do online computer repair but occasionally people i meet in person want me to fix their laptops.

I have a Toshiba Satellite L655D here with a very dim display, i can just barely see it under a flash light. I have replaced the LED screen and the LCD cable and the problem is still there. The only time the backlight has ever come on is as I was closing the screen down while messing with a magnet around the hinge area but i could not duplicate the situation again. I am not exactly sure where the mechanism is on the laptop but still working on it.

Anyone have any ideas? perhaps someone has experienced the same issue with this model?

Edit: I forgot to say external vga works fine.

Thanks.

 

[Kitten Kong]

Have you another screen you could test, even if it's a smashed one?

Does sound like a screen issue to me.

 

[ComputerRepairTech]

no, no 3rd screen to test with

Edit: I forgot to say external vga works fine.

 

[Kitten Kong]

What was the original complaint with the laptop? Dim screen?.

 

[ComputerRepairTech]

original complaint was that display wouldnt come on most of the time and when it did it would go into startup repair.

 

[wavey]

Can you try either screen on another laptop? Your own maybe?

 

[ComputerRepairTech]

Can you try either screen on another laptop? Your own maybe?

dont have another led laptop right now.

 

[shamrin]

If the Toshiba splash screen comes up dim then you are looking at a hardware problem, right? There are only 5 places where the problem could be:

• Bad screen
• Bad cable
• Bad video chip
• Bad "screen lighting circuit" on motherboard
• Bad lid switch

Has to be one of these. It sounds like you've got it down to 4 or 5. Toshiba's aren't super-sensitive to it but you can knock out the lighting circuit if you leave the battery in when you change the screen. It can also pop for some other unknown reason so maybe it arrived that way. The only way I know of to test for this is (without special equipment and/or schematics) is to eliminate the other possibilities - it's pure deduction Watson.

 

[ComputerRepairTech]

If the Toshiba splash screen comes up dim then you are looking at a hardware problem, right? There are only 5 places where the problem could be:

• Bad screen
• Bad cable
• Bad video chip
• Bad "screen lighting circuit" on motherboard
• Bad lid switch

Has to be one of these. It sounds like you've got it down to 4 or 5. Toshiba's aren't super-sensitive to it but you can knock out the lighting circuit if you leave the battery in when you change the screen. It can also pop for some other unknown reason so maybe it arrived that way. The only way I know of to test for this is (without special equipment and/or schematics) is to eliminate the other possibilities - it's pure deduction Watson.

Thank you Sherlock but i was looking for perhaps more specifics of this particular laptop rather than the basics. I figure its either i got a defective part, or its the motherboard/lidswitch or possibly an ambient light sensor...dont have any experience with those so uncertain....dont think this model has one. For a lid switch is it normal for the screen to be dim rather than turn off completely? I suppose I could simply get it into windows and see if it responds to closing the lid down by going into standby.

 

[Boston Pro Comp Serv LLC]

Go into the control panel and power options, there is a slider at the bottom for brightness. It may already be up, or down or where ever, slide it and see if the screen comes back bright. I've seen the come back and work after that, and I've seen some that don't. Worth a shot thou cause it's easy. If that doesn't fix it, my guess would be the board.

 

[JustInspired]

If it came on once when you were messing with a magnet near the hinge, I'd be looking for a stuck lid (magnetic reed) switch maybe?

 

[ComputerRepairTech]

I think my replacement screen was bad too. Heres what i've discovered.

On the new led I can unplug an external monitor and replug it over and over and eventually the backlight will start working but on the old screen it wont do anything at all. I'll try a 3rd screen.

 

[Markverhyden]

In my book the primary culprit for no back lighting is the inverter board. Right under the LCD assembly on this model. Vary rarely does the LCD cause that problem.

 

[ComputerRepairTech]

In my book the primary culprit for no back lighting is the inverter board. Right under the LCD assembly on this model. Vary rarely does the LCD cause that problem.

its a LED screen, no inverter.

 

[Markverhyden]

its a LED screen, no inverter.

I looked at the service manual I have for that model before I posted and it shows a inverter board. But I looked your post over again and it is a D model. When was this made? The SM I have is from 2011.

Somewhere in the equation there needs to be a power supply for the CFL's. When i do a search of L655D inverter they do show a part.

http://www.sparepartswarehouse.com/Toshiba,Satellite,L655D,Laptop,Inverters.aspx

 

[Krynn72]

I think you're on the right track with trying a new screen. I'd say thats the most likely issue (bad replacement part), followed by a short on the board, followed by chipset issue. Cross your fingers for it being a bad replacement part, because the other two are a huge PITA to figure out and fix. Do you have any experience with using a multimeter to diagnose this sort of thing, or experience with reflowing chips?

I looked at the service manual I have for that model before I posted and it shows a inverter board. But I looked your post over again and it is a D model. When was this made? The SM I have is from 2011.

Somewhere in the equation there needs to be a power supply for the CFL's. When i do a search of L655D inverter they do show a part.

http://www.sparepartswarehouse.com/Toshiba,Satellite,L655D,Laptop,Inverters.aspx

Yeah, but if you click any of those links they say "We do not currently have any parts available in this modelline / series / model". I looked at a few videos of people replacing screens on a 655D and none of them had an inverter, plus I think ComputerRepairTech would know one if he saw one

 

[Markverhyden]

I think you're on the right track with trying a new screen. I'd say thats the most likely issue (bad replacement part), followed by a short on the board, followed by chipset issue. Cross your fingers for it being a bad replacement part, because the other two are a huge PITA to figure out and fix. Do you have any experience with using a multimeter to diagnose this sort of thing, or experience with reflowing chips?



Yeah, but if you click any of those links they say "We do not currently have any parts available in this modelline / series / model". I looked at a few videos of people replacing screens on a 655D and none of them had an inverter, plus I think ComputerRepairTech would know one if he saw one

Not doubting the OP. Just that CFL's require power. To be honest I've seen some newer'ish laptops with no discrete inverter for the CFL's.

 

[Romaniac]

I have an L355D with exact same issue. Tested with an inverter and another screen - no go.

Where the heck is the lid switch on these things?

 

[JustInspired]

Look for a magnet (or place for one as they sometimes become dislodged) in the bezel or lid plastic. I have found magnets stuck to hinges or screen brackets before and they are quite small and easily missed.
Another possibility for LED backlights not working is a blown SMD fuse on the motherboard. Always a good idea to remove the battery and press the power button before disassembly.

 

[ComputerRepairTech]

its the motherboard i dunno what the deal is, also the webcam chip gets extremely hot.