Aoc n20wb

[ronhayes]

Hi All
Wonder if any one can help ? I have just had a 20" monitor off my brother he said it was working fine but one day when he switched it on the screen flashed on then went dark.
When i switched it on the green light stays on but no picture displayed, when i used a torch i could see the picture , so no backlights.
I took it apart and tested the backlights with my lcd tester i used the inverter included in that kit.
As you can see from the photo's i have included the screen working with my lcd tester connected.
When i check the volts on each backlight plug at switch on the volts jump up then go back down to 0v after about one second.
Can not find any info on this monitor or a supplier for power board ?
Any help much appreciated.

[vinceroger69]

Re: Aoc n20wb

on the psu is there any writing on top of the inverter transformer as maybe faulty winding on it

[ronhayes]

Re: Aoc n20wb

Hi Vince
Thank you for your help this is what is printed on it.
2374302205p , DARFON2029R , 822012.
Sorry i have not been very active on badcaps but i am a very poorly man at the moment .

[ronhayes]

Re: Aoc n20wb

I have just looked for the inverter transformer on the net and can only see one listed in America for $7.

[ronhayes]

Re: Aoc n20wb

Sorry i mean China

[vinceroger69]

Re: Aoc n20wb

can you take a picture of the top of the transformer and also on the bottom side of the transformer too see if we can work out what windings/pins we need to check the ohms on

EDIT ron heres a good picture of the windings can you check the ohms on them
http://www.iccfl.com/product_info.ph...oducts_id=5450
I have looked online but cant seem too find the winding specs hopefully budm? may have a idea of what the reading should be on a good transformer as you have tested the ccfls and ruled them out already.

[ronhayes]

Re: Aoc n20wb

Here they are hope they are clear enough ?

[vinceroger69]

Re: Aoc n20wb

Here they are hope they are clear enough ?

thanks ron did you see my edit in the above post?

[ronhayes]

Re: Aoc n20wb

Hi Vince
I have just looked at your edit.
Does it have to be removed to test ?
And what pins should i test ?

[vinceroger69]

Re: Aoc n20wb

test in circuit is ok, if you look at the picture in the link i sent you the winding wires you can see which pins they go to and need to test

as monitors are so cheap nowadays you may not want too spend much on parts i wonder if you could use something like this the problem maybe without a schematic finding where to wire it up to and finding where to mount it if you have room
https://www.ebay.co.uk/itm/Universal...wAAOSwu4BVu1OW

[ronhayes]

Re: Aoc n20wb

I have measured ohms in the 20k setting on diode the two centre pins on the end with the six pins i get short 0.00 ohms with buzzer and the two single pins i get 0.46ohms with buzzing.

[ronhayes]

Re: Aoc n20wb

Yes that would be a good alternative but would need to be guided on how to connect ?
I am sure i could find some ware to mount it.

[vinceroger69]

Re: Aoc n20wb

I have measured ohms in the 20k setting on diode the two center pins on the end with the six pins i get short 0.00 ohms with buzzer and the two single pins i get 0.46ohms with buzzing.

i cant find any info on the specs for this transformer im hoping a more experienced member will let us know if this is ok or not
regarding wiring the universal board im not sure but maybe if you can find the lcd panel number? we can look at the lvds pin out and see if we can work where to connect it up too

[vinceroger69]

Re: Aoc n20wb

i wonder how close this service manual is too your monitor yes this service manual uses two inverter transformers but it maybe close enough too help fix yours its a dixon n20w but made by aoc

[ronhayes]

Re: Aoc n20wb

Here is a picture of the labels on the lcd panel

[vinceroger69]

Re: Aoc n20wb

hopefully budm will see this thread and have a idea if those transformer readings are ok or not or any help on fitting that universal board

[ronhayes]

Re: Aoc n20wb

Yes hopefully he will.

[budm]

Re: Aoc n20wb

There are two 8-P9N SMD DUAL MOSFETs (very close to the transfomer for driving the primary side of the Inverter transformer. What are their P/N?
BTW, you lamp tester is made to test 4 lamps, what happen you you connect just only one lamp at a time, do you see the backlights come on for seconds?
BTW, that board 2202139401p is also used in Viewsonic VA2208W, Haans-G HF2296.

[ronhayes]

Re: Aoc n20wb

MOSFET P/N are 4502c AA8 GAR.
Yes the tester can test all four ,So i connected all four but i only used it on its lower volts
Backlights came on and stayed on.

[vinceroger69]

Re: Aoc n20wb

budm what was your thoughts on post 11 good or bad? as i couldnt find any specs on the transformer