Acer aspire 5742g no VGA voltage

[whaldsz]

Re: Acer aspire 5742g no VGA voltage

U13 pin3, JLVDS1 pin 3, what are the voltages?

[bgaservis]

Re: Acer aspire 5742g no VGA voltage

JLVDS1 pin 1-3 = 11-19v ( depends if on battery or AC )
U13 pin 1-3 = 1.5v

[whaldsz]

Re: Acer aspire 5742g no VGA voltage

i got the wrong schematic, pin 4 of JLVDS1 or pin 1 of Q30? This is +LCDVDD which should give 3.3V.

[bgaservis]

Re: Acer aspire 5742g no VGA voltage

Yes, there is 3.3V on +LCDVDD.

[whaldsz]

Re: Acer aspire 5742g no VGA voltage

On page 28, also check u3 and u22. Which display is currently selected, UMA or DISCRETE? If you select the other one, will it exhibit the same behavior?

[bgaservis]

Re: Acer aspire 5742g no VGA voltage

U3 and U22 are not installed on the board, blank spots...
It looks like discrete (Nv) chip is always active ?

[whaldsz]

Re: Acer aspire 5742g no VGA voltage

U18, have you reprogrammed it?

[bgaservis]

Re: Acer aspire 5742g no VGA voltage

Yes, U31 and U18.

[whaldsz]

Re: Acer aspire 5742g no VGA voltage

Then you may try to reflow, reball or replace the gpu as a last resort as robrock1 suggested.

[bgaservis]

Re: Acer aspire 5742g no VGA voltage

yes, it looks like that is the last thing to do
I will update this thread when I change GPU!

Tnx all!

[aimiliano]

Re: Acer aspire 5742g no VGA voltage

i have the same laptop with the same problem!

i dont have vga Voltage all others are ok
when i open it , the leds open for a few seconds and then it closes again.

i have replaced kb926...
but still..

VGA_ON signal is not being sent

u21 is ok not shorted

i cant find
+3vsdgpu also when powering on