Best way to determine if the backlight or it's driver (inverter) is bad.

[Sparky34kv]

I got this used from someone at work. Works flawlessly up until about a month ago. I got it out of my backpack and the backlight for the screen is not working. I do not know the specific type type of backlight that it has, so it may or may not have a seperate inverter. I've tried using the function key and F3 to adjust the brightness up with no success. I have changed screens in laptops before but until I know what's wrong I am not spending money till I know what to replace.

[iomare]

Hi,

Can you provide the exact model or product number (not serial) for further help. Here is how to find it.

https://support.hp.com/my-en/document/c00033108

Can you see an image on the screen (even if very dark)? Is the screen dark at boot (HP logo or in BIOS)?

Let me know,

David

[REO51ST]

Welcome to the HP Support Community @Sparky34kv 

Shining a flashlight/torch at an angle at the display do you see a faint image???

To better assist you, the members will need the exact model number or product number of your laptop???

HP Notebook PCs - How Do I Find My Product Name or Number?

 https://support.hp.com/us-en/document/c00033108

REO

PLEASE DO NOT POST ANY SERIAL NUMBERS

[Sparky34kv]

REO, thanks. I get video to the display, I can see it with a flashlight, just no backlight. It's a Pavilion g7, model g7-1340DX, product A6Z29UA#ABA. I can use it with a monitor, just can't get any backlight output to the display screen.

[REO51ST]

@Sparky34kv 

No inverter so it is the display panel.

HP part number:   641395-001

Maintenance and Service Guide:

http://h10032.www1.hp.com/ctg/Manual/c03538328

When replacing the display make sure to remove the battery and hold down the power button to discharge the laptop.

I have fried a few laptop system boards forgetting to do so.

You will know if the 5th pin on the LCD cable sparks when attachig the new LCD.

REO

[Sparky34kv]

REO, thanks for the information. Is there anything I should check prior to simply replacing the display? I've been looking this up for a while this morning and found references to issues on the motherboard, or at least a fuse for the supply to the backlight. I'm not questioning your answer, I just want to be certain before buying a $70 part for a laptop I have not used very much yet.

[REO51ST]

@Sparky34kv

The only other thing could be the cable???

After thousands of LCD repairs I would say 1-3% had a bad cable.

And I would say 7-8% turn out to be a system board.

We also test around 100-150 LCD's a month using different laptops as testbeds.

And as I said I have fried the LCD backlight supply a few times. "We just scrap them"

No fuse to replace.

REO

[Sparky34kv]

Reo,

     I apologize, I meant to thank you for the help on Saturday. I really appreciate it.

[REO51ST]

@Sparky34kv 

No problem.

Just hope we helped.

REO