ASUS R556L doesnt POST

[KvnTM]

Hey Guys this is my first thread on this forum.

Lets dive straight into the problem. A friend gave me an ASUS R556L and told me the screen stays black. He said he doesnt care about it and i can keep it but i want to fix it for learning purposes.

Some background info:
I measured every power rail on the board with help of Boardview.
Everything is spot on and clean. I checked every rail with an oscilloscope. No noise whatsoever. Nothing is shorted to ground.

When powering up the CPU gets warm pretty fast so i guess the bios does indeed load and the problem is something else than the power rails.

Then problems arrive.. The screen stays black and doesnt initialize. It stays unpowered. I initiliazed it manually on the DP->LVDS Converter with the enable pin and it goes black instantly. No backlight though.
The HDD starts but shuts off after around 5 Seconds, it's still getting power though.

Also when pressing the power button nothing happens and it stays on. Only holding it for several seconds powers it off (which looks like its stuck in POST to me).

I did reflow all RAM chips on the Board (soldered to the mainboard) because it looks like some RAM fault to me. I experienced this behaviour from PCs with failed RAM before. NO i didnt throw it in the oven. Im pretty tech savvy and electronics is my passion since im a little kid. Actually Circuit Board repair is my job so i guess i know what i am doing

If someone is interested in a bios dump of this Laptop, hit me up!

I'd appreciate it if someone is able to help me. Im out of ideas. Thanks

[piernov]

Re: ASUS R556L doesnt POST

Did you actually try to flash the BIOS with a known good dump?
I've got a X550LC motherboard right here that I can't fix, it boots with internal RAM only (after flashing the BIOS). If I try to add a RAM stick, the POST stalls (can see it on power supply ammeter).
You could try disabling the internal RAM, there are some tutorials for some laptop, if you think that's your issue.

Also check the waveform you get on the BIOS chip CS# pin (pin 1) with the oscilloscope.

[KvnTM]

Re: ASUS R556L doesnt POST

Actually no. I dont know if it's a good dump. (I cant find any known good dumps)
Maybe i'll try to disable the internal RAM..

Upon boot there is data on the SPI lines so i guess it does something at least.

[piernov]

Re: ASUS R556L doesnt POST

Could be a corrupt BIOS. The motherboard in this laptop is apparently a X555LD. Check around this forum, there are a few dumps out there you should try out.

[KvnTM]

Re: ASUS R556L doesnt POST

Thanks for your suggestions. I actually already tried some dumps from this forum. Most of them left the board in an non working state. The cpu stays relatively cool without the heatsink. Which tells me that the bios is not correct. Maybe i'll try some more...

[KvnTM]

Re: ASUS R556L doesnt POST

Update: I flashed a different bios dump and voila it works again! POST Takes like 10 Seconds but it goes straight into the BIOS Setup.

[mcplslg123]

Re: ASUS R556L doesnt POST

Update: I flashed a different bios dump and voila it works again! POST Takes like 10 Seconds but it goes straight into the BIOS Setup.

Post taking little longer is due to me region. Just clean me region of your bios. Going directly to setup-i doubnt its not detecting hdd. Try with another hdd.

[piernov]

Re: ASUS R556L doesnt POST

Can be a pain finding a good BIOS. Could you tell us which motherboard is it exactly (model number, revision and options — discrete/UMA, integrated RAM for example—) and what BIOS did you use? It may help others.
Going straight into BIOS setup may also be because the CMOS settings and the UEFI boot sequence are bad. Clear settings and boot off of a USB key.

[KvnTM]

Re: ASUS R556L doesnt POST

@mcplslg123: I had no harddrive connected at all. Just the board and display. The BIOS Screen just said ‚Im Fine‘ to me. I connected a harddrive, installed windows aaand it was done.

@piernov: Sure! I‘ll do that later when i got time. I searched like 4 hours to find a working dump on some russian forum. Jeez we need a gigantic database for every model ever repaired.

[cacla]

Re: ASUS R556L doesnt POST

Sent me the sn for you model i will find your dump in asus system

[Th3_uN1Qu3]

Re: ASUS R556L doesnt POST

I can do database, but not enough time. I definitely can do Clean ME though. Attach the dump you flashed and I can fix it for you, PM me if you want the tools and info to fix the ME region yourself. It is not hard to do.

[KvnTM]

Re: ASUS R556L doesnt POST

I can do database, but not enough time. I definitely can do Clean ME though. Attach the dump you flashed and I can fix it for you, PM me if you want the tools and info to fix the ME region yourself. It is not hard to do.

Would be great if you give me the tools or fix the dump for me. The display stays black for about a minute when i power it on. And waking from sleep results in a black screen. I guess the bios dump is from the model with a nvidia gpu? since there is "n15v" in the name of it which is a Geforce 840m. I guess it is waiting for the gpu which doesnt exist? clear me up on that one. cheers.

I attached the dump that worked for me. Including the issue i have atm. my model is the R556LA.

[KvnTM]

Re: ASUS R556L doesnt POST

EDIT:

I found the correct one. POST takes a normal 2 Seconds, Sleep works, BIOS information matches the laptop model.

Laptop: ASUS R556L
MB: X555LD Rev. 3.3
BIOS: X555LABF1601

I attached the .ROM below.

For everybody else: THIS version seems to be the one for X555LD Rev 3.3 WITHOUT discrete nvidia gpu.

The post above seems to be the one WITH the nvidia gpu.