Re: ASUS Q502LA LED Screen/Backlight Issues

Hello Forum Members...
Wanted to post that I got the laptop fixed, thanks to some kind folks on this site! The screen was in fact bad. Replaced it AND the cable with new ones, and it is up and running great again. I wound up also purchasing another motherboard, as I could not find G5244A31U high side switch, or an equivalent in the US. I destroyed the one I un-soldered on the original board. I should have checked availability before I messed with it. I'm new to these tiny components, and obviously need to be more careful when working...

Re: ASUS Q502LA LED Screen/Backlight Issues

Thanks for the help everyone! So I followed reformatt's idea, and checked the voltage coming from EDP_VDD_EN right at power up. It happened very quickly, but there indeed was voltage present for about 1 second, and then it went back to 0. This tells me that there is no EDP communication present from the display. Since I have 19v present, I have decided to purchase another display. Just have to get U4505 soldered back on. This looks like it might be a challenge, due to the fact that the pins are on the bottom of the chip. These SMD components...

Re: ASUS Q502LA LED Screen/Backlight Issues

Thanks for the tip! Just removed U4505, and there is still no voltage on pin 4. Does this mean the CPU is damaged, or is some other underlying issue preventing voltage on EDP_VDD_EN?

Re: ASUS Q502LA LED Screen/Backlight Issues

Hello!

Thanks so much for helping me out! There is no voltage on pin 4 of U4505. There is no voltage on any pins of U4505 except pin 1. There is no voltage on either side of L4501 coil either. Checked resistance on R4581 and it is right at 100K. I see that pin 1 of R4581 traces to EDP_VDD_EN on the CPU. I'm guessing since there is no voltage present, that this could be the problem? What voltage should be there? Is something else preventing the CPU from applying voltage here?
Thanks!!

Re: ASUS Q502LA LED Screen/Backlight Issues

Did a little more testing, and found +3v on pin 1 of U4505, but no voltage on pin 6. The boardview says +3 on pins 13, 14, and 19 of J4502 screen connector. No voltage on any of these. I can upload the boardview, but I don't want to violate any forum rules. This laptop is a very good friend of mines, and I sure would like to give it back to her working! Any ideas on whether or not the screen itself might have damaged the motherboard circuit, and maybe I need to order another one?? Thanks!!

Hello Everyone.
Glad to be a member here! I am pretty new to working on laptops. I was hoping I was going to able to fix this one, but I am having some problems...
This laptop works perfectly with a HDMI monitor hooked up to it. Here in lies the problem. No backlight! So i figured, replace the screen/backlight assembly. Then I had very dim video (could be seen with a flashlight) but still no backlight. Found after doing some homework that it had a blown ferrite bead, which I replaced. Like an idiot, I forgot to unplug the battery, and when I was hooking back up the 30 pin cable,...

Re: New Members - please post your introductions here

Hello Forum Members!
I am from the US, close to Lake Michigan. I am a electronics hobbyist, and always looking to learn new things. I have successfully built and repaired vacuum tube amplifiers, and some other larger electronic circuits. I am currently delving into the world of laptop repair. That is how I found this forum! I am searching for some direction from some folks that have more knowledge in the field than i do. I am excited to learn things, and hopefully get them working properly again!

Thank...