Acer Aspire 5750-6845 dead

[tibimakai]

Re: Acer Aspire 5750-6845 dead

At:
pin #8-Vreg3= 3.273V
pin #13-EN= 1.965V
pin #17-Vreg5= 4.964V

[tibimakai]

Re: Acer Aspire 5750-6845 dead

Any ideas?

[whaldsz]

Re: Acer Aspire 5750-6845 dead

Reading looks ok on those pins. Try to press the power button and check if you get voltages at pl4 and pl5. If you get normal voltages, led lights should turn on.

[tibimakai]

Re: Acer Aspire 5750-6845 dead

I did that, and nothing happened.

[whaldsz]

Re: Acer Aspire 5750-6845 dead

Does pin32 of u20 goes low whn you press power button? Voltage of your cmos battery?

[tibimakai]

Re: Acer Aspire 5750-6845 dead

I will have to check on these, when I get home. The battery, if I remember well I have measured and it wasn't to low.
Pin32 is the command for ON/OFF?

[tibimakai]

Re: Acer Aspire 5750-6845 dead

It goes from 0.001V to 0V.
Battery is 2.88V, but I have pit another one and it didn't make any difference.

[tibimakai]

Re: Acer Aspire 5750-6845 dead

Anybody can help?
Thank you

Tibor

[whaldsz]

Re: Acer Aspire 5750-6845 dead

Voltage at Pin 1, 6, 12, 19?

[tibimakai]

Re: Acer Aspire 5750-6845 dead

At pin #1, 6 I'm getting 0V.
At pin #12 I'm getting -0.003V
At pin #19 I'm getting 0V

[whaldsz]

Re: Acer Aspire 5750-6845 dead

You get no voltage at PL4 and PL5 because pin 1, 6 or ENTRIPx is 0v.

Measure the voltage at pin 2 of PQ25, EC_ON pin 2 of PQ27.

[tibimakai]

Re: Acer Aspire 5750-6845 dead

There is 0V on all three pins(on or off).

[whaldsz]

Re: Acer Aspire 5750-6845 dead

VL is connected to VREG5, so you should have 5V at pin2 of PR64. Check if PQ24 and PQ25 is ok.

[whaldsz]

Re: Acer Aspire 5750-6845 dead

Measure resistance of PQ25 from pin2 to ground. If you get a short here then either of the two transistor is defective. You may need to pull them out and test out of circuit to confirm.

[kev4eva]

Re: Acer Aspire 5750-6845 dead

i have a same model with 19volts in however missing 3 vreg and 5vreg....will use these steps to see what is exactly fault as am stuck myself.Same symptoms dead an no led or activity.

[tibimakai]

Re: Acer Aspire 5750-6845 dead

But, probably yours doesn't have a damaged USB port(the one with the remote PCB mini board).
I will check soon those transistors. Thank you for helping.
I'm repairing LCD/LED TVs also. I have just repaired a 46" LED Westinghouse.

[tibimakai]

Re: Acer Aspire 5750-6845 dead

It seems that I had a bit of problem and I haven't noticed it in time.
The negative wires were broken off at the DC in plug.
Now I have 4.82V, 0.011V and 0V at pin #2.(PQ25)
Still no voltages at the U20.
PQ24 is a 6 pin little IC.

[whaldsz]

Re: Acer Aspire 5750-6845 dead

Where do you read 4.82v? What are the voltages at pin 1-6 of PQ24?

Also what are the voltages at the pins of PQ26. The gate is connected to EC_ON and comes from ENE KB930.

[tibimakai]

Re: Acer Aspire 5750-6845 dead

On pin#1(base) I have the 4.286V(sorry I had it wrong).
It seems to high for base, no?
Collector pin#3 is 0.011V.
I don't know which one is pin#1 at PQ24.
If I look at the markings on it, from the readable side, I start writing the pin voltages from bottom left side toward right and going up and toward the left side.
pin#1=0V
pin#2=0.011V
pin#3=1.118V
pin#4=0V
pin#5=0.11V
pin#6=1.54V
PQ26
pin#1=0.005V
pin#2=0V
pin#3=4.286V

[whaldsz]

Re: Acer Aspire 5750-6845 dead

Looks like your voltage readings on PQ24 is ok. Why? there is a voltage at the SOURCE of both mosfet(see ) that is enough to put ENTRIPx high and make VOUTx to give 3.3V, 5V at PL4, PL5, provided pin13 EN Of PU2 is also high.

On PQ26, the result is odd. 4.286V is for pin 1 right?

One more time, could you please measure all voltage at the pins of PU2 for confirmation before you change this IC?