LCD screen model M270HTN02.0 need help in identyfying a component

[soflesone]

Hi, I would like to ask you for help in identifying a component on the T-con of an AUO M270HTN02.0 matrix the T-con model is 27M14-C05.

Short story, as it happens with this matrix, most often damaged element is N mosfet marked 12h34 and so it was in this case, as you can see on the picture, I replaced it with A09T (I know it's not perfectly straight soldered but it's just being soldered at the moment) unfortunately the problem did not disappear the screen was still not displaying the content and was glowing white. The gate of the replaced mosfet had 0.17V so it was suspected that P303-19 was probably defective. After soldering out P303-19, the resistance on the above-mentioned gate returned from 1.5kΩ to 20kΩ. Unfortunately, this still had no effect and after starting P303-19 was again damaged, heated in the upper part at pins 13 and 14 and that's where I started looking for further problem.

It turned out that the element marked on the photo as W1 is shorted on all pins, unfortunately I am not able to clearly determine what this element is and here I ask for help in determining this, from my search I found several options:

on this page https://www.s-manuals.com/smd/w1 the W1 circuit is labeled as a Zener diode

while on this page: https://www.hotenda.com/marking-code/se ... st/W1.html it is marked as NE687M13 transistor https://datasheetspdf.com/pdf/574855/CEL/NE687M13/1

and on this page http://tromil.pl/wp-content/uploads/201 ... d-cz.2.pdf there is information that it is a PNP transistor with code BFT92 and after searching this code you can find transistors with markings W1w, W1s, W1p where mine is clearly marked W1

I will be very grateful for any help 

[fzabkar]

There is a similarly labelled W5 component at Q301, so I would think that W1 is a BJT transistor or MOSFET.

Also, Q303 is marked "1CH18", so I'm guessing it is manufactured by the same company as "12H34".

Q303, D303 and L304 appear to form a boost converter, with the output voltage appearing across C327 and C328. Q303 appears to be a low-sat NPN BJT or N-channel MOSFET.

Q305 appears to be a 2DD1664 manufactured by Diodes Inc:
https://www.diodes.com/assets/Datasheets/ds31143.pdf

Perhaps the others are also manufactured by Diodes Inc?

[DavidAlfa]

This pdf has data for the P303-11, which might be the same thing with a different voltage output?
Pins 13 and 14 are connected to a mosfet, so that's probably that .

[DavidAlfa]

The mosfet might be AO3401L.
The datasheet doesn't show the marking.
Edit:
Check out this schematic, page 35, the circuit looks very similar, but uses n-ch fet (AOH3106)

[fzabkar]

The marking code for AO3401L appears to be "A1xx":

http://www.smdmark.com/en-US/search/code?id=a1xx
https://www.google.com/search?q=AO3401L&tbs=isz:m,itp:photo&tbm=isch

[soflesone]

Thank you much for your answers, I know much more thanks to you  I just made an order with 5 P303-19 ICs and we will be testing. First I will try to solder BFT92 transistor and see what will hapen. As for now I tried to solder in that W1 place another transistor with 2CH35 mark (I found it on similar T-con in same monitor serie but older model with only 60hz refresh, it has much less components on T-con) and still nothing on pin 4 (gate for replaced A09T) so there is no 12V passing but now got 1.3V on coil where should be 30V, nothing is warm or burning. P303 is definitely broken and needs to be replaced

[fzabkar]

The topology is an inverting boost converter.

The average DC voltage across the coil should be 0V.

There should be a negative supply voltage at the anode of the diode ("26D").

[soflesone]

Yes I'm getting -14V on one of diode and -7V on the other

[fzabkar]

If I understand the circuit correctly, there should be a negative voltage at the anode of the 26D diode adjacent to W1 (inverting boost converter), and a positive voltage on the cathode of D303 (boost converter).

[soflesone]

Hi there again, I come with an update. Today I have received P303-19, it took quite long because ICs were ordered from China. On first shot I tried to put new P303 IC and in place of unidentified component I soldered BFT92 25mA 15V 5GHz and that was a mistake, it burned instantly after turning power supply on. P303 survived so I tried to put back 2CH35 mosfet from another T-con I mentioned earlier and it worked. Display is working without any issues 

I'm writing this so maybe someday someone will have a similar problem because this is a common fault in this monitor and this will save repairable units from beeing utilized.

One more time thank you all a lot, thanks to you I saved it from dump, saved some money (it costed me in total 75$) and I'm happy with that 

[brkklcl]

Hello, I have the same problem. I searched for the input fuse and Q308 a09t. I couldn't find it in my country. I changed it to AO3400(N55G) but the white screen still continued. P 303-19 3rd and 4th pins got hot. W1 burned. I bought a Zenner diode with the market code W1 (BZX84C2V4) and changed it but the result didn't change. Right now I have W1 and N55G and the area I mentioned about P303 is getting hot. Also, I noticed in the picture that you installed P302-19 instead of P303-19. Are they the same? I hope someone will answer. I have been dealing with this monitor for a long time. I deal with electronics as a hobby and this monitor was more important to me than buying a new one. Since I don't know English, I used translate. Sorry for the mistakes.

[StowAway]

I bought a Zenner diode with the market code W1 (BZX84C2V4) and changed it but the result didn't change.

Actually, W1 (Q302) is P-mosfet. I'm almost sure that AO3401. Here is actual tester output of Q302 element: P-E-MOS 1G, 2S, 3D; Vt=0.81V, Cg=1.61nF, Rds=0.00. In my case label is W1701.

If anyone needs it, here is the tester output also for Q301 W5717 (25H02 in my case): P-E-MOS 1G, 2S, 3D; Vt=1.80V, Cg=862pF, Rds=0.00.

I think in your case P303-19 is damaged. You need to order it from China or find it on a donor, there are some tcon boards with such a controller. I found it on 55T32-C0F.
But there is a big chance that the controller will not work without the appropriate firmware inside.
If P303.19 responds via I2C, I would save the registers from it. This can be done through the test points next to the connector, they marked as TPI2C_P303.

In any case, I am attaching the datasheet for the Chinese clone P303.19 (G2510S) and its firmware from the M270HTN02.2 matrix, which in theory should work the same way on the M270HTN02.0.