Acer x223w first white screen, now no backlight

[retiredcaps]

Re: Acer x223w first white screen, now no backlight

U501 and U502 are n channel mosfets. Thanks to the excellent photo, I can read the part number. The datasheet is at

http://pdf1.alldatasheet.com/datashe.../AP9971GD.html

Check for shorts between S1-D1, S1-G1, and D1-G1. Do the same for the "2"'s. See the datasheet for the proper pin orientation.

Any resistance reading below 30 ohms suggest it may be shorted. Report all readings.

[teri3s]

Re: Acer x223w first white screen, now no backlight

Across F802 I get +5V
The jumper above, "J808" I get +17.6V

[retiredcaps]

Re: Acer x223w first white screen, now no backlight

I just noticed that when I touch the black lead to ground and the red lead to the heatsink next to CN801, the voltmeter is reading minus 75V.

I believe that heatsink is "live". It is attached to the power mosfet. I'm guessing your ground was probably on the cold side, that is why you get -75V reading.

Do you get any DC voltage reading across F802? If yes, what is it?

[teri3s]

Re: Acer x223w first white screen, now no backlight

Thank you retiredcaps, I was a bit nervous about the pics had to retake them and then started worrying about the long shadows.

I just noticed that when I touch the black lead to ground and the red lead to the heatsink next to CN801, the voltmeter is reading minus 75V. The other heatsink registers no voltage.

2) CN801
1. VCC 5V (reads 5V)
2. VCC 5V (reads 5V)
3. GND
4. GND
remaining 4 pins (in order, on/off, Brightness, Vol, Mute) read zero volts.

3) U106 (Logic Board)

Pin 1 reads 0 volts
Pin 2 reads 3.2 volts
Pin 3 reads 4.7 volts

4) F802 (Inverter Side of PSU)
Reads below 1.0 ohms (using a DMM and an analog)

[retiredcaps]

Re: Acer x223w first white screen, now no backlight

Started checking the voltages, they seemed alright.

1) Excellent photos. It helps a lot in troubleshooting.

2) On CN801, what are the voltages for all the pins?

3) On the logic board, there is a voltage regulator at U106. What are the voltages for all 3 pins with respect to ground?

4) Check picofuse F802 (yellow fuse near top of board on the inverter side). A good fuse should measure less than 1.0 ohms.

[teri3s]

Yesterday, monitor was in use for a few hours then screen just turned white. I could still see a bit of the video I was playing showing through. Tried unplugging power, plugged back in...same issue. Screen was a messy white and grey.

When I turned it on, it would come on, with blue led "on light" on keyboard, switch to amber with screen going black, then back on with the messy white.

Took monitor apart, disconnected input board, plugged back in a few times, turned on, and screen was completely white as though the backlight was up to maximum intensity. Started checking the voltages, they seemed alright. Turned monitor on again later after combing online for similar issues. Backlight no longer came on, couldn't see anything on screen.

At present I get no voltage readings from inverter side of board.

I am a novice when it comes to the intricacies of component testing, so any advice is appreciated.

Edit: right now when hook everything up, and turn it on, the led goes from amber to blue and stays blue.