Sony VGN-SZ3XP (PCG-6N2M) no backlight.

[Andreasbest]

Hello.
I receive a VGN-SZ3XP Sony Vaio model with no backlight, it has LED screen so no inverter problem, i changed screen but still no backlight so i guess no problem on screen it self and/or in the attached board.
I want to know which one is the backlight voltage to follow it from mainboard to LVDS flex and found out where it stops.
Thank you in advance!

[BlueMidnight]

Re: Sony VGN-SZ3XP (PCG-6N2M) no backlight.

Can you see an image at all if you shine a light on it? Is it truly just the backlight? Do you get an image through the VGA port? That model is actually a bit older and has an nVidia G72M GPU. That's one of the ones nVidia officially admitted were prone to failure.

Everything pretty much goes straight to the GPU. The backlight enable and control lines do go through a multiplexer chip (IC760) to select whether they are controlled by the northbridge or the discrete GPU. And there are also some pull-down resistors on those lines.

The backlight enable line also goes through IC3200, which is just an AND gate. If both pins 1 and 2 are high, then pin 4 is high. Otherwise pin 4 is low. So you can just make sure all three of those pins are high..

I'm not 100% sure what the voltage is supposed to be on those signal lines, but it's probably 5V if I had to guess.

And there is also 5V supply voltage at the LCD connector pins 1 and 2.

And that's about all.

[Andreasbest]

Re: Sony VGN-SZ3XP (PCG-6N2M) no backlight.

Yes i get image if i shine light on it and i get image from VGA port too.
I was thinking that perhaps is the flex cable that's why i want to follow the line and found out where it stops.
I'll check IC3200, thank you!