Re: Acer x223w first white screen, now no backlight
That first picture with the white messy screen I got. I didn't get the second one with the vertical lines however. Even after the monitor was disassembled I still only got the white messy screen until the backlight stopped working completely.
How long have you been using that monitor btw?
teri3s
Member
Last Activity: 11-08-2011, 08:02 AM
Joined: 10-09-2011
Location: Anguilla
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Re: Acer x223w first white screen, now no backlight
Nevermind, it was both N-channel mosfets U501 and U502 trying to basically meltLeave a comment:
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Re: Acer x223w first white screen, now no backlight
I just plugged in the power board by itself and smoke started emanating from that transformer (T502) on the bottom left side. I noticed it getting warm yesterday.
Recommendations?Leave a comment:
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Re: Acer x223w first white screen, now no backlight
It started doing something weird where one rail would get sufficient power and the other wouldn't. Power LED going amber if there was 5V on the 5V rail, but then the 18V rail (or whatever its supposed to be) would drop to 17 something volts.
Then sometimes when you cycled the power, the 18V rail would be sufficiently powered and the power led would go blue, but the 5V would be under 5V. Now the power LED went off completely and the voltages across the board are just haywire, fluctuating rapidly but far below what...Last edited by teri3s; 10-12-2011, 11:44 AM.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Which one is the inverter's fuse?Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Hrmmmmm.......I've been running some tests on the OZ9938GN chip and it seems to demonstrate some odd behaviour. Elsewhere I found someone recommending grounding either the 'Timer' on Pin 3 or the 'Overvoltage Protection' on Pin 7 to test if the problem is the backlight tubes, the inverters or the IC.
After ground Pin 3 or Pin 7 the voltage reading from VDDA (supply voltage input) Pin 2 was 3.14V. (With the monitor 'off' the reading is 2.41V) Backlight still was not on and transformers were not getting warm.
...Last edited by teri3s; 10-12-2011, 07:27 AM.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
That 16 pin IC is difficult to read, it looks like OZ9938GN. Googled it to see what would come up and came across [URL="https://www.badcaps.net/forum/showthread.php?t=16613"]this[/URL]
Pin 2 (VDD based on the datasheet) to ground reads as 240 ohms.
[URL="http://monitor.espec.ws//files/oz9938_140.pdf"]OZ9938GN Datasheet[/URL]Re: Acer x223w first white screen, now no backlight
That 16 pin IC is difficult to read, it looks like OZ9938GN. Googled it to see what would comeLast edited by teri3s; 10-11-2011, 07:15 PM.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Okay, um.............tried a few times to make sure......and I'm not seeing anything displayed on the screen while shining the flash light on it in the dark.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Not even sure how to explain the testing of the mosfets. Pretty much every combination has the display unchanging from '1' except with ohms set at 200k, with the black probe at S1 and the red probe at D1 I get a number that keeps ascending. I tried discharging the gate with my finger first, but right now the number is 33.5 ohms ascending.
The behaviour of both mosfets is identical, seemingly synchronized.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
I just rechecked CN801 (plugging in the logic board this time) with the digital multimeter against the ground where the plug is and I get
While off
1) 5.05v (VCC 5V)
2) 5.05v (VCC 5V)
3) 0V (GND)
4) 0V (GND)
5) 0.03V (on/off)
6) 2.56V (Brightness)
7) 0.04V (Vol) -----no speakers on this monitor
8) 1.75V (Mute)
While on
all other pins are the same values except
5) 3.12V (on/off)
Brightness voltage is the sameLast edited by teri3s; 10-11-2011, 05:50 PM.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
With Rx10 setting on analog, about 500 ohms at both the red and yellow dots.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Scale was set to 10x
The "2's" displayed the same pattern.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Thanks for that PlainBill. Yeah, I got an inkling that "across" would cause confusion.
The picofuse is not open. It reads nearly 0 ohms when the probes are placed at opposite ends. No voltage registers if probed "across".
If I go from a ground point to the picofuse I get the 5V reading.Last edited by teri3s; 10-11-2011, 06:45 AM.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
I am not sure what I'm looking for exactly in terms of ohmmeter readings while checking for shorts so I'll just post what I found and if I say anything stupid.......well please bear with me lol.
Am I supposed to desolder these devices to test them?
But in the meantime, using an analog meter, when I touch the probes to S1 and D1 it goes from near 0ohms and then gradually falls back to infinite ohms.
D1 and G1 it goes from about 50 ohms and the needle falls back to infinite resistance.
...Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Not sure what you mean pedro?Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Alright retiredcaps, will do. Also, a sincere thank you for all the help thus far.Leave a comment:
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Re: Acer x223w first white screen, now no backlight
Across F802 I get +5V
The jumper above, "J808" I get +17.6VLast edited by teri3s; 10-10-2011, 05:55 PM.Leave a comment:
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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.
...Last edited by teri3s; 10-10-2011, 05:09 PM.Leave a comment:
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Acer x223w first white screen, now no backlight
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...Last edited by teri3s; 10-10-2011, 04:28 PM. -
Re: Acer x193w
Alright PlainBill, thanks for the info.
I'll try and put together those pictures for you. BTW, this power board is ILPI-033Leave a comment:
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