Problems with Samsung 740N monitors

[pedro]

Originally Posted by Behemot

I got two 940B together with 240B, all three have the same symptoms.

As these are NOT 740N's, it would have been better to start these as a separate thread so that others with those models would have more chance of finding this discussion.

[Behemot]

As these have exactly the same board as 740N's, that is also the reason Search pointed me here, I would stay in this thread, thank you very much;-)

Line is the same, 7 means 17", 9 means 19", yes?

[pedro]

Originally Posted by Behemot

As these have exactly the same board as 740N's, that is also the reason Search pointed me here, I would stay in this thread, thank you very much;-)

Boards are often "re-used" between models, but if your monitors were listed under their actual model# then a basic newbie search would find them, and all it would take would be a cross-ref there to the 740 thread(s).

[Behemot]

Here it is again as an attachement.

[retiredcaps]

What is the pwm IC chip on the back of the board?

[Behemot]

I am not able to read that clearly, it looks like BIT3195(0?). However, earlier posts here talk about BIT3193.

[retiredcaps]

Originally Posted by Behemot

I am not able to read that clearly, it looks like BIT3195(0?). However, earlier posts here talk about BIT3193.

http://pdf1.alldatasheet.com/datashe...C/BIT3193.html

According to datasheet, pin 7 is GND and pin 10 is VDD.

1) See if pin 7 and pin 10 are shorted.

2) If not, measure the DC voltage on pin 10.

[mockingbird]

Can you post a picture of the logic board please?

[sowi]

I have an 740N with a IP-35155A board. After switching the screen on the backlight is on for about two seconds and then goes off. The screen itself is still displaying, i can see it with a flashlight.
I replaced all capacitors which didn't help. The board has both transformators in one shell instead of two separate ones. The resistance on output side between 1 and 2 is about 1kohm, between 3 and 4 about 7.5kohm. So i think the transformer is faulty. On the upperside it has printed TM-1017, on the downside SEM1852. Where can i get a drop-in replacement for this transformer? I'm in europe.
Thanks.

[jetadm123]

Originally Posted by sowi

I have an 740N with a IP-35155A board. After switching the screen on the backlight is on for about two seconds and then goes off. The screen itself is still displaying, i can see it with a flashlight.
I replaced all capacitors which didn't help. The board has both transformators in one shell instead of two separate ones. The resistance on output side between 1 and 2 is about 1kohm, between 3 and 4 about 7.5kohm. So i think the transformer is faulty. On the upperside it has printed TM-1017, on the downside SEM1852. Where can i get a drop-in replacement for this transformer? I'm in europe.
Thanks.

TM-1017 is readily available on Ebay.

[indrair]

Dear all.
I have 740N and totally dead, led off dan smell something burn before it's dead. Before dead my 740N can be displayed but need about 5-10 minutes. I cek, one component, i don't know what it's melt, i can identified the series because the mark is missing, anyone knows what the cmponent it's?.
I'm also already change the 3 cap (1000uf/16v) and 1 470uf/25v, but it's not working. and where is the 3A pico fuse found? am i must change this fuse too??

Thanks for help.

[indrair3]

Originally Posted by indrair

Dear all.
I have 740N and totally dead, led off dan smell something burn before it's dead. Before dead my 740N can be displayed but need about 5-10 minutes. I cek, one component, i don't know what it's melt, i can identified the series because the mark is missing, anyone knows what the cmponent it's?.
I'm also already change the 3 cap (1000uf/16v) and 1 470uf/25v, but it's not working. and where is the 3A pico fuse found? am i must change this fuse too??

Thanks for help.

up..up.. help please

[selldoor]

Ok - you are not going to get much help by bumping a post.
You would get more help if you didnt post pictures in line and if the front of the board picture was the other way up so the numbers could be read.
A quick look through this thread doesnt show a board like this one and I have tried to find the board but failed - didnt spend a lot of time as I cant really read the model no.
Please state the model number and revision of the board and get a magnifing glass and post any numbers off the burnt component that you can decipher.

[Behemot]

This board does not look very good to say. It seems there is no fuse at all, thats usually the reas for half of the components to burn. Also thre are ordinary diodes instead of bridge rectifiers.

Anyway, to me, the component looks more like manual (re)soldered/changed to me. Is that some kind of dual transistor in one package?

[budm]

@INDRAIR3:
Service manual:
http://elektrotanya.com/?q=showresul...oria=&kat2=all
That DUAL MOSFETs are badly burnt out, you need to look at the service manual for the P/N first. The IC (on the bottom side of the board) that drives the MOSFETs may be damaged also.

[selldoor]

Having enhanced your pic I think it might be one of these
http://ndft.com.ua/sites/default/fil...ic/stu407d.jpg

[Behemot]

Originally Posted by Behemot

Here it is again as an attachement.

Anyone has the board shown in my earlier post (#304)? What is the R316 value please?

[selldoor]

@behomot
Hi - have you taken it out - can you see the colours on the underside?
What does it measure?

Here is another board http://obrazki.elektroda.net/58_1284496626.jpg

Is that Brown Grey Black Gold - 18ohms 5%

Or Brown Black grey silver 1000M ohms 10%

[selldoor]

Better Idea - PM Bocca and ask him he has the same board and is working on it now.

[Behemot]

I have it but the restistor is totaly burned and reads as wire :-D I have replied in the thread of his…