• Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

Backlight on laptop not working

Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
Anyone ever seen this happen? I got this toshiba x505-q870 from a friend because he dropped broke the screen and needed money. The backlight on the broken screen was working but then when I switched it out for the new one it stopped working (as in no matter which screen I plug in the backlights don't work). Any ideas why this is happening?
 
Joined
Jan 17, 2010
Messages
12,280 (2.36/day)
Location
Oregon
System Name Juliette // HTPC
Processor Intel i7 9700K // AMD Ryzen 5 5600G
Motherboard ASUS Prime Z390X-A // ASRock B550 ITX-AC
Cooling Noctua NH-U12 Black // Stock
Memory Corsair DDR4 3600 32gb //G.SKILL Trident Z Royal Series 16GB (2 x 8GB) 3600
Video Card(s) ASUS RTX4070 OC// GTX 1650
Storage Samsung 970 EVO NVMe 1Tb, Intel 665p Series M.2 2280 1TB // Samsung 1Tb SSD
Display(s) ASUS VP348QGL 34" Quad HD 3440 x 1440 // 55" LG 4K SK8000 Series
Case Seasonic SYNCRO Q7// Silverstone Granada GD05
Audio Device(s) Focusrite Scarlett 4i4 // HDMI to Samsung HW-R650 sound bar
Power Supply Seasonic SYNCRO 750 W // CORSAIR Vengeance 650M
Mouse Cooler Master MM710 53G
Keyboard Logitech 920-009300 G512 SE
Software Windows 10 Pro // Windows 10 Pro
Were the wires go threw the hinge is very delicate. Try the other wires from the other laptop.
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
I looked at the wires very carefully because I know that is one area prone to damage but it looks like its good. There is only one laptop, two screens.
 
Joined
Oct 2, 2005
Messages
3,059 (0.45/day)
Location
Baltimore MD
Processor Ryzen 5900X
Motherboard ASUS Prime X470 Pro
Cooling Arctic liquid freezer II 240
Memory 2 x 16 Gb Gskill Trident Z 3600 Mhz
Video Card(s) MSI Ventus 3060 Ti OC
Storage Samsung 960 EVO 500 Gb / 860 EVO 1 Tb
Display(s) Dell S2719DGF
Case Lian Li Lancool II Mesh
Audio Device(s) Soundblaster Z
Power Supply Corsair RM850x
Mouse Logitech G703
Keyboard Logitech G513
Software Win 11
are you sure it was the screen that broke and not the inverter for the backlight
 
Joined
Jan 23, 2011
Messages
521 (0.11/day)
Location
St. Louis, MO
System Name Desktop
Processor Intel i7 13700K
Motherboard MSI Z790 Tomahawk D4
Cooling Corsair XC7 Block / Corsair XG7 Block EK 360PE Radiator EK 120XE Radiator 5x EK Vadar Furious Fans
Memory 64GB Corsair Dominator DDR4-3200
Video Card(s) MSI RTX 4090 Gaming X Trio
Storage 1TB WD Black SN850 / 4TB Inland Premium / 8TB WD Black HDD
Display(s) Alienware AW3821DW / ASUS TUF VG279QM
Case Lian-Li Dynamic 011 XL ROG
Audio Device(s) Razer Nommo Pro Speakers / Creative AE-9 w/ Beyerdynamic MMX 300
Power Supply EVGA P2 1200W Platinum
Mouse Razer Naga Pro
Keyboard Deathstalker Pro
So you replaced the broken LCD panel with a new one and now there is not any power going to the screen?? If you put a flashlight up to the screen can you see a picture??

Double check the inverter going to the LCD if there is one, pretty sure that Qosmio has one. Generally it only fits one way and the polarity of the inverter is marked with a blue dot or some other kind of marking.

Also, sometimes though Toshiba doesn't usually do this, the panel you ordered as replacement might not need an inverter at all.

And again double check the LVDS cable going to the LCD panel. It can be loose.
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
are you sure it was the screen that broke and not the inverter for the backlight
http://www.pchub.com/uph/photos/site/Image/Assembly/dis_lcd_inverter_01_overview520.JPG

It does have an inverter and thats what I was starting to think was the problem. When I did some Googling that problem popped up a couple times.
Once again, everything is plugged in correctly and I can barely see an image on the screen (because the screen is working just not the back light).
 
Joined
Jan 17, 2010
Messages
12,280 (2.36/day)
Location
Oregon
System Name Juliette // HTPC
Processor Intel i7 9700K // AMD Ryzen 5 5600G
Motherboard ASUS Prime Z390X-A // ASRock B550 ITX-AC
Cooling Noctua NH-U12 Black // Stock
Memory Corsair DDR4 3600 32gb //G.SKILL Trident Z Royal Series 16GB (2 x 8GB) 3600
Video Card(s) ASUS RTX4070 OC// GTX 1650
Storage Samsung 970 EVO NVMe 1Tb, Intel 665p Series M.2 2280 1TB // Samsung 1Tb SSD
Display(s) ASUS VP348QGL 34" Quad HD 3440 x 1440 // 55" LG 4K SK8000 Series
Case Seasonic SYNCRO Q7// Silverstone Granada GD05
Audio Device(s) Focusrite Scarlett 4i4 // HDMI to Samsung HW-R650 sound bar
Power Supply Seasonic SYNCRO 750 W // CORSAIR Vengeance 650M
Mouse Cooler Master MM710 53G
Keyboard Logitech 920-009300 G512 SE
Software Windows 10 Pro // Windows 10 Pro
You can get a inverter and wiring on e bay.
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
Joined
Jan 23, 2011
Messages
521 (0.11/day)
Location
St. Louis, MO
System Name Desktop
Processor Intel i7 13700K
Motherboard MSI Z790 Tomahawk D4
Cooling Corsair XC7 Block / Corsair XG7 Block EK 360PE Radiator EK 120XE Radiator 5x EK Vadar Furious Fans
Memory 64GB Corsair Dominator DDR4-3200
Video Card(s) MSI RTX 4090 Gaming X Trio
Storage 1TB WD Black SN850 / 4TB Inland Premium / 8TB WD Black HDD
Display(s) Alienware AW3821DW / ASUS TUF VG279QM
Case Lian-Li Dynamic 011 XL ROG
Audio Device(s) Razer Nommo Pro Speakers / Creative AE-9 w/ Beyerdynamic MMX 300
Power Supply EVGA P2 1200W Platinum
Mouse Razer Naga Pro
Keyboard Deathstalker Pro
If you can on the bottom of the laptop give me the following information:

Model Number: (Usually PSU, PSK or something other than the X505 number)

I am an ASP for just about every manufacturer, I can get you the right part numbers for your particular laptop. Toshiba manuals are quite nice :) :) :)
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
its a x505-q870, but here is a pic with everything else
 
Joined
Mar 12, 2009
Messages
1,080 (0.20/day)
Location
SCOTLAND!
System Name Machine XV
Processor Dual Xeon E5 2670 V3 Turbo unlocked
Motherboard Kllisre X99 Dual
Cooling 120mm heatsink
Memory 64gb DDR4 ECC
Video Card(s) RX 480 4Gb
Storage 1Tb NVME SSD
Display(s) 19" + 23" + 17"
Case ATX
Audio Device(s) XFi xtreme USB
Power Supply 800W
Software Windows 10
There is a few on eBay search x505 inverter.
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
There is a few on eBay search x505 inverter.

I did, but the question still stands of which exact one I need. Maybe it doesn't even matter?
 
Joined
Mar 12, 2009
Messages
1,080 (0.20/day)
Location
SCOTLAND!
System Name Machine XV
Processor Dual Xeon E5 2670 V3 Turbo unlocked
Motherboard Kllisre X99 Dual
Cooling 120mm heatsink
Memory 64gb DDR4 ECC
Video Card(s) RX 480 4Gb
Storage 1Tb NVME SSD
Display(s) 19" + 23" + 17"
Case ATX
Audio Device(s) XFi xtreme USB
Power Supply 800W
Software Windows 10
There should be a model number on the one you have so Just try eBay for every number on it.
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
yeah I did that before and none of them were my exact model number
 
Joined
Jan 29, 2012
Messages
6,441 (1.44/day)
Location
Florida
System Name natr0n-PC
Processor Ryzen 5950x/5600x
Motherboard B450 AORUS M
Cooling EK AIO 360 - 6 fan action
Memory Patriot - Viper Steel DDR4 (B-Die)(4x8GB)
Video Card(s) EVGA 3070ti FTW
Storage Various
Display(s) PIXIO IPS 240Hz 1080P
Case Thermaltake Level 20 VT
Audio Device(s) LOXJIE D10 + Kinter Amp + 6 Bookshelf Speakers Sony+JVC+Sony
Power Supply Super Flower Leadex III ARGB 80+ Gold 650W
Software XP/7/8.1/10
Benchmark Scores http://valid.x86.fr/79kuh6
I tried to fix a similar issue you describe for someone. I ordered new screen, inverters all that bs.

In the end nothing worked. could only use with a external monitor.

Letting you know as this will be a real hassle if you try it.
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
^that best not be whats wrong...
 
Joined
Mar 12, 2009
Messages
1,080 (0.20/day)
Location
SCOTLAND!
System Name Machine XV
Processor Dual Xeon E5 2670 V3 Turbo unlocked
Motherboard Kllisre X99 Dual
Cooling 120mm heatsink
Memory 64gb DDR4 ECC
Video Card(s) RX 480 4Gb
Storage 1Tb NVME SSD
Display(s) 19" + 23" + 17"
Case ATX
Audio Device(s) XFi xtreme USB
Power Supply 800W
Software Windows 10
It's either the inverter or ribbon cable it is extremely rare for the inverter power source on a motherboard to fail unless it's been shorted.



Can you post the inverter numbers and a photo of both sides of the inverter?
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
Thats what I thought. Its just weird that it was working and as soon as I took the old screen off it failed.. anyway here is the inverter
 
Joined
Jan 17, 2010
Messages
12,280 (2.36/day)
Location
Oregon
System Name Juliette // HTPC
Processor Intel i7 9700K // AMD Ryzen 5 5600G
Motherboard ASUS Prime Z390X-A // ASRock B550 ITX-AC
Cooling Noctua NH-U12 Black // Stock
Memory Corsair DDR4 3600 32gb //G.SKILL Trident Z Royal Series 16GB (2 x 8GB) 3600
Video Card(s) ASUS RTX4070 OC// GTX 1650
Storage Samsung 970 EVO NVMe 1Tb, Intel 665p Series M.2 2280 1TB // Samsung 1Tb SSD
Display(s) ASUS VP348QGL 34" Quad HD 3440 x 1440 // 55" LG 4K SK8000 Series
Case Seasonic SYNCRO Q7// Silverstone Granada GD05
Audio Device(s) Focusrite Scarlett 4i4 // HDMI to Samsung HW-R650 sound bar
Power Supply Seasonic SYNCRO 750 W // CORSAIR Vengeance 650M
Mouse Cooler Master MM710 53G
Keyboard Logitech 920-009300 G512 SE
Software Windows 10 Pro // Windows 10 Pro
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
Joined
Jan 17, 2010
Messages
12,280 (2.36/day)
Location
Oregon
System Name Juliette // HTPC
Processor Intel i7 9700K // AMD Ryzen 5 5600G
Motherboard ASUS Prime Z390X-A // ASRock B550 ITX-AC
Cooling Noctua NH-U12 Black // Stock
Memory Corsair DDR4 3600 32gb //G.SKILL Trident Z Royal Series 16GB (2 x 8GB) 3600
Video Card(s) ASUS RTX4070 OC// GTX 1650
Storage Samsung 970 EVO NVMe 1Tb, Intel 665p Series M.2 2280 1TB // Samsung 1Tb SSD
Display(s) ASUS VP348QGL 34" Quad HD 3440 x 1440 // 55" LG 4K SK8000 Series
Case Seasonic SYNCRO Q7// Silverstone Granada GD05
Audio Device(s) Focusrite Scarlett 4i4 // HDMI to Samsung HW-R650 sound bar
Power Supply Seasonic SYNCRO 750 W // CORSAIR Vengeance 650M
Mouse Cooler Master MM710 53G
Keyboard Logitech 920-009300 G512 SE
Software Windows 10 Pro // Windows 10 Pro
the wires all look perfect, I guess its something to look into though. Is there a good way to test them?

I have been threw this a few times. Looks are deceiving. Just replace them if your going to replace the inverter.
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
If you read what I said in the first post neither of the screens backlights work so its not that
 
Joined
Jan 23, 2011
Messages
521 (0.11/day)
Location
St. Louis, MO
System Name Desktop
Processor Intel i7 13700K
Motherboard MSI Z790 Tomahawk D4
Cooling Corsair XC7 Block / Corsair XG7 Block EK 360PE Radiator EK 120XE Radiator 5x EK Vadar Furious Fans
Memory 64GB Corsair Dominator DDR4-3200
Video Card(s) MSI RTX 4090 Gaming X Trio
Storage 1TB WD Black SN850 / 4TB Inland Premium / 8TB WD Black HDD
Display(s) Alienware AW3821DW / ASUS TUF VG279QM
Case Lian-Li Dynamic 011 XL ROG
Audio Device(s) Razer Nommo Pro Speakers / Creative AE-9 w/ Beyerdynamic MMX 300
Power Supply EVGA P2 1200W Platinum
Mouse Razer Naga Pro
Keyboard Deathstalker Pro
Sorry for the delay anonymous6366,

Toshiba changed their ASP website and I needed to get access again.

Here are your part numbers:

A000048360 - Original Inverter that came with the unit

These two part numbers are the other inverters that will work because usually the original is hard to find. A000048370 A000048380

A000051860 - LVDS Cable from motherboard to panel

This is another cable that will work. A000053600

A000047700 - This is the original Panel number. Toshiba only lists one compatible panel for your laptop.
 
Joined
Jun 20, 2009
Messages
286 (0.05/day)
System Name Nazgul
Processor Core i7 7700k
Motherboard MSI Krait Gaming 170a
Cooling Corsair H100i
Memory 16gb DDR4 3200mhz
Video Card(s) EVGA FTW+ GTX970
Storage Samsung 512gb SSD, 500gb 7200rpm storage
Display(s) Benq 144hz 1080p
Case Fractal Design Define r5 titanium window
Power Supply Corsair AX850
Mouse Logitech
Keyboard Razer
Software Windows 7 Pro 64 bit
Top