Hi guys,
I have a friend's Dell 3779 that came to me with severely shorted mobo. Did not manage to isolate the cause, most likely that was a bga shorted. Went for a replacement motherboard. Got one from China, apparently it's been tested prior to shipping. The mobo starts up normally but I am getting no display whatsoever.
Tried using external monitor, but being blind I am not sure if laptops goes as far as booting to Windows, a d without it I cannot get hdmi to work. Can't see boot menu options to make sure it boots to Windows. Went ahead and did a blind bios update, which I think went well (bios recovery shortcut, left arrow once, enter. After a couple of minutes got a reboot as expected.). Did not change a thing though. LCD Bist does not work, screen is still black.
Why do I think the motherboard boots up?
1 - trying to run bios recovery with no USB stick inside gives me a correct beep code.
2 - keyboard and touchpad are somewhat responsive (caps lock lights up when pressed, keyboard backlight goes on when I touch the touchpad etc).
I am not sure if the mobo I received is faulty, or could the original fault damage the LCD as well. I'm wondering if is there any quite simple way to measure the Edp connector output to determine if the actual LCD is faulty, or if the signals are not produced by motherboard at all. Got the schematics (it's for la-f611p compared to mine la-f612p, but Edp output is the same). I am getting the +dcbat_lcd (18v). Not sure which line is responsible for detecting and actually powering up the screen. Could someone more experienced advise? Many, many thanks in advance.
The schematic can be found at this page , the Edp pinout is on page 29.
I have a friend's Dell 3779 that came to me with severely shorted mobo. Did not manage to isolate the cause, most likely that was a bga shorted. Went for a replacement motherboard. Got one from China, apparently it's been tested prior to shipping. The mobo starts up normally but I am getting no display whatsoever.
Tried using external monitor, but being blind I am not sure if laptops goes as far as booting to Windows, a d without it I cannot get hdmi to work. Can't see boot menu options to make sure it boots to Windows. Went ahead and did a blind bios update, which I think went well (bios recovery shortcut, left arrow once, enter. After a couple of minutes got a reboot as expected.). Did not change a thing though. LCD Bist does not work, screen is still black.
Why do I think the motherboard boots up?
1 - trying to run bios recovery with no USB stick inside gives me a correct beep code.
2 - keyboard and touchpad are somewhat responsive (caps lock lights up when pressed, keyboard backlight goes on when I touch the touchpad etc).
I am not sure if the mobo I received is faulty, or could the original fault damage the LCD as well. I'm wondering if is there any quite simple way to measure the Edp connector output to determine if the actual LCD is faulty, or if the signals are not produced by motherboard at all. Got the schematics (it's for la-f611p compared to mine la-f612p, but Edp output is the same). I am getting the +dcbat_lcd (18v). Not sure which line is responsible for detecting and actually powering up the screen. Could someone more experienced advise? Many, many thanks in advance.
The schematic can be found at this page , the Edp pinout is on page 29.
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