Samsung R540 black screen

[Learn2Day]

Hi guys, need help. I'm a moderate knowledge repair tech but I'm looking to know more..

I have a busted R540 and its problems are it doesn't boot. It lights up power LED and the fan spins really fast but does nothing else.
The laptop didn't overheated or anything similar, one day the laptop just didn't boot anymore.

I've already tried all the usual stuff, re-seat everything, tested AC adapter and battery, removed coin battery, etc and although the laptop didn't overheated i even tried a quick reflow to the GPU and chipset without success... After reading a post here on the forum i also tried to replace the CPU, but no success.

I'm suspecting the issue might be in the power module, according to some random posts i've read googling around, but I have no idea how to diagnose and repair it.
I found the schematics here, but I'm too noob to make sense of anything.. Sorry!
http://elektrotanya.com/samsung_np-r.../download.html

Can anyone help?

Thanks in advance, L2D.

[trebo]

Re: Samsung R540 black screen

Hi guys, need help. I'm a moderate knowledge repair tech but I'm looking to know more..

I have a busted R540 and its problems are it doesn't boot. It lights up power LED and the fan spins really fast but does nothing else.
The laptop didn't overheated or anything similar, one day the laptop just didn't boot anymore.

I've already tried all the usual stuff, re-seat everything, tested AC adapter and battery, removed coin battery, etc and although the laptop didn't overheated i even tried a quick reflow to the GPU and chipset without success... After reading a post here on the forum i also tried to replace the CPU, but no success.

I'm suspecting the issue might be in the power module, according to some random posts i've read googling around, but I have no idea how to diagnose and repair it.
I found the schematics here, but I'm too noob to make sense of anything.. Sorry!
http://elektrotanya.com/samsung_np-r.../download.html

Can anyone help?

Thanks in advance, L2D.

try ram, one stick a time, both slots, or swapping ram sticks for known good ones
try removing ODD
both issues can give those symptoms

[tomodachi]

Re: Samsung R540 black screen

Also check if LVDS cable is connected to LED display, happened me once,
good luck

[Learn2Day]

Re: Samsung R540 black screen

try ram, one stick a time, both slots, or swapping ram sticks for known good ones
try removing ODD
both issues can give those symptoms

Also check if LVDS cable is connected to LED display, happened me once,
good luck

Thanks for the tips guys, but all this was already done as well as other "basic" steps... Laptop doesn't even respond to caps lock, wifi activation etc.
The problem is in the main board, and based on what I've read, I'm almost sure that's within the power module. Any diagnosing tips? If necessary i could post a couple pictures of the main board.

Cheers.

[Learn2Day]

Re: Samsung R540 black screen

Please, some help would be appreciated..

[spidey]

Re: Samsung R540 black screen

measure voltages on coils, also check it from the schematic. Share your measurements here.

[Learn2Day]

Re: Samsung R540 black screen

Hi spidey, thanks. Sorry for the delayed response but this week it's been a busy one.

I've measured coils B500 and B501 and voltages are normal (19V). I forgot to mention the laptop charges the battery fine and also powers on battery. Sorry if i was misleading saying the issue is power module, and not one of the power modules. Can you help understand which points are most important to measure to identify the faulty part or module?

BTW, correct link for schematics is:


Thanks, L2D.

[RoLOMiX]

Re: Samsung R540 black screen

Hello, Check Nec Tokin, like toshiba, done 3 boards with sucess.