Trouble with smd transistor reference

[rick6]

I have a few HP lcds here that i'm fixing. Most of them have the usual problems, either bulging capacitors or dead backlight driver transistors, but two of them have a more uncommon problem, a burned transistor on the logic board.

These are smd parts (SOT-23 or SOT23R package) and since this a bit is out of my comfort zone i am having trouble making sense of these components references. They are totally charred but gladly i was able to get two good monitors with the same logic board and take note of the codes for each transistor. They are marked A011 and A016 and are in the same place of each logic board so they might be doing the same thing. I can not find anything usable online with these values so i assume these are codes for references.

I was able to find this site http://www.marsport.org.uk/smd/smd0.htm
For 011 (note that it's not A011) i get SO2369R or equivalent 2N2369 and nothing for A016. I'm able to get the smd version of the 2N2369 transistor at a local store but since i'm not even sure my logic of "code for references" is correct i would thank some guidance with this subject.

I can take some photos if necessary.

Thank you in advance

 

[BGAmodz]

Hi can you recheck the values and also how they are written , in SMD usually the main reference is written in big characters the last ones are in small characters ( usually refering to the type of the transistor or the mosfet ).

I have found these on sot23 maybe yours is on the A01 catehory :

A01 , A02, A03,A04

https://www.s-manuals.com/pdf/datasheet/j/2/j201-j204,_sst201-sst204_calogic.pdf

 

[BGAmodz]

Put some pics of the card if possible

 

[rick6]

Hi BGAmodz. Before going straight away to the photos let me correct myself about what i stated previously. I said that i had two good boards but i didn't notice that those boards are from the same model.

So here is what i have->

The first damaged board model 4H.L1G01.A12 (burned component marked with red):


Closeup of the burned component:




Now the second damaged board model 48.L1G01.A01 (burned component marked with red):


Closeup of the burned component:







Now for the good boards i have->

Good board model 48.L1G01.A01:


Closeup of the good component code A011:




Second good board model 48.L1G01.A02:


Closeup of the good component code A016:



So with this i should conclude that the burned component of the 48.L1G01.A01 was marked with A011.
Even though i don't have any good 4H.L1G01.A12 board i think i can conclude that the burned component was marked with A016 because even terribly wasted as that transistor is, you can almost see a "16" there, and the good 48.L1G01.A02 board i have here uses a A016 so there you go. Actually these boards are so similar that i guess i could get the same transistor for all of them and it should work ok. Problem is that my google skills are failling me and i wasn't able to get the schematics of these boards.

Can you tell me what transistor should this A011\A016 be?

Thanks in advance!

 

[rick6]

Well after searching for a while i'm willing to guess this is a ELM13401CA that is a P-channel MOSFET which feeds 5 volts into the LCD panel. Both mosfets got burned because the previous person who opened the monitors to replace the LCD crushed the ribbon and shorted the output of this component to ground. I have high hopes of getting this working again now.

A good equivalent seems to be the AO3401 which is easly found on ebay in large quantities for a reasonable price.

I'll give some feedback when i get these devices, probably a month from now.