Samsung Syncmaster 940BW White screen

[Sparks88]

I have a sammy 940BW 19" monitor with a white screen, did a visual and on the video board a component has blown, its designated Q400, unfortunately its totally white so unreadable, anyone had the same problem and managed to identify the component or a schematic would be very usefull, i have also checked the lcd board and a smd ceramic cap seems to have been stressed because its got black scorch marks on the pcb lands.
Any pointers appreciated.

[budm]

Re: Samsung Syncmaster 940BW White screen

The Q400 is on the logic board (the board where you plug in the VGA cable)? Or it is on the board attached to the LCD panel assembly.
you can download service manual from www.elektrotanya.com

[selldoor]

Re: Samsung Syncmaster 940BW White screen

Cant see a q400 on the schema perhaps different revision.
Can you post good clear pics of the boards - fronts and backs label them as you refer to them so we know which you are referrring to and also a close up where the q400 was and a pic of the remains.
Could you also update your profile with country and mains voltage.

[Sparks88]

Re: Samsung Syncmaster 940BW White screen

Q400 is on the logic board and the ceramic cap on the lcd, i have managed to get a manual after having to put up with a load of adverts, managed to get all needed components from farnells in uk so will see if it powers up after i change the mosfet and cap, if it works i intend on recapping the board cos its got capxon, here goes with fingers crossed, will update after i finish.

[Sparks88]

Re: Samsung Syncmaster 940BW White screen

replaced the 100nf cap on the lcd and the mosfet q400, cleaned the board because the tracks under q400 were burned away and had to put in a link across to where the tracks were missing, powered on and was rewarded with a good picture, success, another monitor salvaged from the scrappers.

[Tetsujin]

Re: Samsung Syncmaster 940BW White screen

Hello there, i have the same problem with my samsyng synchmaster too, but i noticed on logic board the piece marked in red square being fat, i mean isnt flat...
So, what kind of SMD is that? And with what i can replace?
Because when i power on, backlight work but the screen is white, like there is no cable connected from logic board to lcd screen.

And here is the printscreen: http://s15.postimage.org/fqmtuemvt/DSCN0205.jpg

[selldoor]

Re: Samsung Syncmaster 940BW White screen

That is a good picture - can you re-post it using "manage attachments"

found by scrolling down in "go advanced" under quick reply.

I thought there should be a q400 on the board as mentioned earlier in the thread but there is not.

Can you decipher the part number?

White screen is often a blown fuse on the panel board - can you do a picture of that?

[Tetsujin]

Re: Samsung Syncmaster 940BW White screen

The part number is not listed in electrical part list of the board.
On the board the part is noted in a square with Q301, and on it is coded TR2 or TA2, like in the picture above, but the Q301 is not listed on electrical part list.
The fuse on the panel board is good i`ve checked it with a multimeter.
I cant make good pictures now because i dont know where is my data cable...

[selldoor]

Re: Samsung Syncmaster 940BW White screen

Is there something after the TR2?

[gavs]

Re: Samsung Syncmaster 940BW White screen

You can thank to obscure colleague from China, who had published the following Service Manual: According to this document Q301 is P−Channel MOSFET NTR2101P(8.0V, 3.7A, ).

[Tetsujin]

Re: Samsung Syncmaster 940BW White screen

Is there something after the TR2?

Yes is a 3 but turned down, i think is the lot number

You can thank to obscure colleague from China, who had published the following Service Manual: According to this document Q301 is P−Channel MOSFET NTR2101P(8.0V, 3.7A, ).

I will, because i guess that part is a NTR2101P-D mosfet.
Thanks very much.
I`ll keep in touch if the problem is solved..that device on my board is blown, like a half expanded popcorn :P