AOC 913Swl has a white screen.

[Neshone]

Hello,

I have monitor AOC 913Swl. It has problem with white screen like this:
https://www.youtube.com/watch?v=KF43WKaZBEk

I try erase contacts on flat cable like on this video:
http://www.youtube.com/watch?v=FfbmQRuqDD0

But it didn't help.

I check PSU board and I think that it's good. All Voltages seams good. (Only on 12V pins I have 14.90V)

I can post all voltages if that is required

[momaka]

Re: AOC 913Swl has a white screen.

Likely T-con board issue. Check fuse on T-con board. It should be near the LVDS connector. The T-con board is the one that is attached to the LCD display TFT matrix.

If possible, post some clear pictures of the T-con, so we can assist you further. Use the forum's "Manage Attachments" (found after clicking the "Go Advanced" button) feature to submit your pictures.

[Neshone]

Re: AOC 913Swl has a white screen.

Tnx momaka for your reply

I searched fuse on all boards but without success.

In this post I will attach images of all board and original image of screen.

This AOC 913Swl was broken before 5 months. I left him in basement.

After 5 months I try again and all was alright first 1-2 min. Later problem returned.

The Screen has very slow response and if I change screen image(for example, pres CTRL+ALT+DEL) on display screen change after several second and change very slow.

I don't know what is 6R4 M16, but that is suspiciously.

[1supertech]

Re: AOC 913Swl has a white screen.

In the fourth pic from left fuse is F1 it has P15 written on it I think tab bonds are going bad.

[momaka]

Re: AOC 913Swl has a white screen.

I searched fuse on all boards but without success.

In this post I will attach images of all board and original image of screen.

Ah okay, I see that this is not a complete white screen problem - just washed out.

In that case, the fuse on the T-con board is likely NOT the problem (which is F1, with "P15" written on it, as 1supertech pointed out. Still, check it just in case with your multimeter. It should have good continuity. 1-2 Ohms resistance max (or less, depending on how good your multimeter is).

I'm thinking this is likely NOT tab bonds either, since the whole screen seems to be affected and there are no vertical lines.

Try this: when you press the "MENU" button on the monitor, does the OSD also appear with strange colors too?

Another test to run is to check the voltages on the T-con board (that is the board in picture #4 you posted). There are small golden dots on your T-con board - these are voltage test points. What you need to do is use your multimeter to measure the voltage between ground (monitor metal chassis) and the following test points:
VDD (located right below fuse F1)
AVDO (located top right of that "6R4 M16" inductor")
VGH (I can't find it on your board, but it should be there. Sometimes called V_GON or VDDG)
VGL (I can't find it on your board, but it should be there. Sometimes called V_GOFF or VEEG)

The problem could also be bad gamma IC, I think. If you can, please post a full picture of the T-con board.

Changing the electrolytic capacitors on the video/logic board (picture #2 you posted) could also be the problem.

Sorry I can't give you more exact guidance where the problem is. I've seen problems like this before and often times they either couldn't be solved or the problem was different for each one, so there were different solutions. Hopefully, the above tests should help determine where the problem could be.

[Neshone]

Re: AOC 913Swl has a white screen.

I check the voltages on board:

VDD=5.04V
AVDO=12.65V
VGH=27.8V
VGL=25.4V

Resistance of the fuse F1 is about 0.7ohms.

When I press MENU button colours are strange and it have slow respons.

[momaka]

Re: AOC 913Swl has a white screen.

VGL=25.4V

And that might be it.

VGL is usually -5 to -10 Volts. It is responsible for making pixels in the LCD appear dark (whereas VGH turns them ON and makes them pass-through the backlight).

Speaking of which, I can't find where test point VGL is on your T-con. Could you point it out to me. I know there should be one somewhere if there is VGH.

Basically, bad VGL could be caused by a bad transistor, bad diode, or shorted ceramic capacitor. Once I know where VGL is, I should be able to point it out to you which components to check.

[Neshone]

Re: AOC 913Swl has a white screen.

I check now and MGL=24.4V, but I can't find VGL,V_GOFF or VEEG.

I checked several times but nothing...

[momaka]

Re: AOC 913Swl has a white screen.

Okay, I see some test points called VOFF, VOFF1, VOFF2, and VOFF3. Check those. If you don't see a negative voltage there, can you list all of the test points you see on the board? Your pictures are a bit out of focus, so I can't read some of the test point names.

By the way, I don't see a test point called MGL either. I see MLG. Not that it matters, I just wanted to point out how tricky it can get to read those small test points sometimes even with the board in front of you.

[Neshone]

Re: AOC 913Swl has a white screen.

Test points are:

RP2
OUT1
MLG
LV0, LV1, LV2, LV3, LV4, LV5
LV0+, LV1+, LV2+, LV3+, LV4+, LV5+
OUT684
VOFF1, VOFF2, VOFF3
VGH
XON
AVDOS
SW
OUT605
OUT1368
VDO
RX0+, RX1+, RX2+, RXCLT+, RX3+
RX0, RX1, RX2, RXCLT, RX3
DVDOS
DVDO
OUT1338
OE1CPV
AGING
OE2
TEST
MPOL
LOAD
OUT2053
OUT2736
V1, V2, V3, V4, V5, V6, V7
OUT2737
OUT3420
V8, V9, V10, V11, V12, V13, V14
PWRC2
PWRC1
CSC
OUT4104
LV1P
LVCKP
LV4P, LV0P, LV2P, LV3P, LV5P
LV1N, LV4N, LVON, LV2N, LV3N, LV5N

That's all

[momaka]

Re: AOC 913Swl has a white screen.

That's all

Yes, seems like it.

Okay, so check the voltages on VOFF, VOFF1, VOFF2, and VOFF3. There has to be a negative voltage with respect to ground on one of these test points. At least I haven't seen an LCD t-con board without one.

[Neshone]

Re: AOC 913Swl has a white screen.

Voltage on all VOFF are same and it's -7,66V

[momaka]

Re: AOC 913Swl has a white screen.

Good voltage ^ .

Unfortunately, that means the problem is likely caused either by IC0/IC1 or the LCD panel is bad.

Can you post the part number on IC0? I believe that should be the gamma IC. IC1 is Novatek NT71206FG, but I can't find a datasheet anywhere for it to see what it does. Good news is that you can find it for sale online.

Also, try cleaning the contacts one more time. Maybe use some isopropyl alcohol too. And make sure the solder joints on the connector(s) looks good and not cracked.

[Neshone]

Re: AOC 913Swl has a white screen.

Ic0 -
g16
1287

ic1 -
nt71206f6-603
1139-66
d5sr1

ic4
gh17k
132n61


ic5
17075e
tg133


I try cleaning the contacts... but nothing...

[momaka]

Re: AOC 913Swl has a white screen.

Okay, I can't find a datasheet for IC0, but it doesn't look like the gamma IC, so that is probably not the problem. That means IC1 is likely the gamma IC.

IC4 is a linear voltage regulator, probably for IC1 and IC0. Check the voltage on the input of IC4 (the right-most pin) and the output voltage (center-pin or tab on top). Report what values you get.