Smasung SyncMaster 913N Monitor wouldnot display images

[PlainBill]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Hi,

I have finished testing and the results are below. It seems a little odd for most of them to have no resistance then again I am no expert.

top right ic:

1-2 0
1-8 0
2-8 0
3-4 19.8
3-5 0
4-5 0

bottem right ic

1-2 0
1-8 0
2-8 0
3-4 19.8
3-5 0
4-5

Daniel

Something IS strange. Attach a picture of the DMM with the selector switch in the position you were using.

PlainBill

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Hi,

I have finished testing and the results are below. It seems a little odd for most of them to have no resistance then again I am no expert.

top right ic:

1-2 0
1-8 0
2-8 0
3-4 19.8
3-5 0
4-5 0

bottem right ic

1-2 0
1-8 0
2-8 0
3-4 19.8
3-5 0
4-5

Daniel

[PlainBill]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Thanks for your reply once again. I'll try to get better results with the camera for future pictures.

IC Info:

top right red:

first code 4502c
second code aa5q c or o

bottem right red:

first code 4502c
second code aa5oc

blue left:

first and second line codes i cannot read
third line code: v48332.4t

Hopefully that is ok the little ones are alot easier to read funnily enough.

We have a winner!! The two ICs are AF4502C, complementary mosfets in a single package. The datasheet is here.

Rather than pulling apart a working monitor, check the mosfets for shorts. For each IC, measure the resistance between pins 1,2,8 (1-2, 1-8, 2-8) and 3,4,5 (3-4, 3-5, 4-5).

We'll ignore the controller IC for the time being.

PlainBill

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Thanks for your reply once again. I'll try to get better results with the camera for future pictures.

IC Info:

top right red:

first code 4502c
second code aa5q c or o

bottem right red:

first code 4502c
second code aa5oc

blue left:

first and second line codes i cannot read
third line code: v48332.4t

Hopefully that is ok the little ones are alot easier to read funnily enough.

[PlainBill]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

PlainBill,

Thanks for your reply much appreciated. In regards to testing stuff then safety is key and I certainly would not start testing stuff while plugged into the mains or with capacitors that are not fully de-charged first. I am new to electronics and hope to fix this however there is alot to learn and do right the first time.

In regards to pictures I will try my best however the 7.1MP camera I have becomes blurred when trying to photograph the circuits. I'm hoping the pictures are good enough to view etc, please let me know if they are not and I will re-photograph.

Electronics covers a very wide field. A lot of it is incomprehensible to me (what the heck is 'circular polarization?'). One of the most important things to remember is "One hand in your pocket when working on live circuits." Other things are les obvious - like capacitors can hold a charge for an incredibly long time in some cases.

There is nothing wrong with the camera. The fault lies in the technique. After a LOT of disastrous results, I found that using a tripod (or otherwise steadying the camera), and turning off the flash will produce excellent pictures.

Now, the good news - the results were 'good enough' - kinda. I've marked up the most useful one. The two ICs circled in red are most likely the inverter drivers. IF I am right, they will have identical part numbers. What are they? The IC circled in blue is the inverter controller. The part number of that would help understand how the circuit works.

PlainBill

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

PlainBill,

Thanks for your reply much appreciated. In regards to testing stuff then safety is key and I certainly would not start testing stuff while plugged into the mains or with capacitors that are not fully de-charged first. I am new to electronics and hope to fix this however there is alot to learn and do right the first time.

In regards to pictures I will try my best however the 7.1MP camera I have becomes blurred when trying to photograph the circuits. I'm hoping the pictures are good enough to view etc, please let me know if they are not and I will re-photograph.

[PlainBill]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Hi Guys,

Apologies for replying to an old thread however this is the only place on google that seems to be exactly related to my problem. I also have a samsung 913n syncmaster. The front green led is flashing really quickly. I have inspected all the capacitors for bulging and have tested each with a DMM aswell as the resistors and diodes which all come back fine. I did also try the 5+6 pin soldered together which in turn the green power led didn't even come on and something on the psu was making a clicking sound.

I have tested the four plastic connecters at the left top and bottem side of the board, two wires come from the screen and plug into this little white boxes on the psu and there appears to be no voltage coming out of them at all.

Has anyone been able to fix this issue? I've got three more of these displays that are working ok. I added two pictures to this post.

Daniel

There are several possible causes. My usual approach would be to swap parts between the 'victim' and one of the working monitors. You want to make sure you know WHICH board is bad. By your description, I would say the most likely culprit is the power supply / inverter board.

If the problem IS the power supply / inverter board it could be either one or more bad caps in the power supply OR one or more shorted transistors in the inverter. In either case, a picture of the back of the circuit board will help us help you. The fact that the only cap with a readable label is a CapXon (sometimes referred to as a crapxon) leads me to suspect them.

A few points: While starting a new thread doesn't strain the server or otherwise cost money, it IS nice to have all problems with a particular model of monitor in the same thread is convenient. Extending it IS a good idea, even if the problem is slightly different.

Soldering points on a circuit board because somebody said it works is one way of releasing the magic smoke in an IC. NOT recommended.

About the only capacitor flaw a DMM will detect is a short. And that is very unlikely to be the problem.

Probing the CCFL lines in a working monitor is a good way to provide a major realignment in your life. These lines carry 600-1000 volts at 100 Khz, and can provide in excess of 10 ma of current. This will kill a DMM quickly. Do it with one hand touching the metal of the monitor could send it through your heart. It probably wouldn't be fatal, but a major cleanup would be necessary, especially if your sphincters relax as you are trying to let go.

PlainBill

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Hi Guys,

Apologies for replying to an old thread however this is the only place on google that seems to be exactly related to my problem. I also have a samsung 913n syncmaster. The front green led is flashing really quickly. I have inspected all the capacitors for bulging and have tested each with a DMM aswell as the resistors and diodes which all come back fine. I did also try the 5+6 pin soldered together which in turn the green power led didn't even come on and something on the psu was making a clicking sound.

I have tested the four plastic connecters at the left top and bottem side of the board, two wires come from the screen and plug into this little white boxes on the psu and there appears to be no voltage coming out of them at all.

Has anyone been able to fix this issue? I've got three more of these displays that are working ok. I added two pictures to this post.

Daniel

[bathuu]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Well, my joy did not last long.
After having tested monitor for an hour, it failed to display images and start showing "Not Optimum Mode" symptoms. So I guess one problem seems to transferred to another. Hope this one has a way around it.
Cheers all. Any suggestions, what I should do now?

[EGuevarae]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Strange case. Congratulations, and follow Gonzo's advice replacing those caps.

[bathuu]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Thanks for response Gonzo,
There was a post in DT Forum, which guy said he simply bridged 2 pins and his monitor has been going good for like several months. So this bridging would cause any damage to other parts of board in the long run? Or it won't be serious concern?
Cheers

[gonzo0815]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

The problem seems to be a bad signal prozessor, which degrades over time and then will need more voltage to work correctly. But sure, this is just an hypothesis.
Personally i would not bridge those pins completely, as it may could be too high a voltage in the long run. Just try the 47R resitor, wich would be far more conservative at this time.

Any way, don`t forget your Sam young capacitors. I would highly recommend to replace those, as it would not cost too much and they will or are already marginal.
I would recommend Panasonic FC or FM series, which should be available in most areas.
Even your SMD capacitors are Samyoung......

[bathuu]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

UNBELIEVABLE!!!!!!!!!

After just soldering pin 5 and 6 together, my monitor is back into life.
WOOOOOOOW.

Thanks for contribution all, Specially to Gonzo and Eguevarae.

But still curious to know what was the cause of such defect.

Cheers all. Everyone have a wonderful day.

[bathuu]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Thanks for reply, Eguevarae. I have attached a picture of inverter board that has DC output to the Logic board. Which wires do test? What value they should show?
Cheers

[EGuevarae]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Sorry, my bad. It is typo, I meant 713.
I'm newbie to electronics. Just don't know how to check voltages coming from inverter board. I have DMM, If you could enlighten me little bit. Which wires do I need to test? And on settings DMM should be set?
Next, I'm considering to solder 5,6 pin as advised Gonzo.
Cheers cheers, thanks for reply

On the upper left part of the Inv/PSU board you have a connector that has labels like "on/off","gnd", 5v, etc.
That's the place for testing. Post a closeup of that portion of the board and we can tell you where to put the DMM probes.

[EGuevarae]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

bathuu,

Although there aren't any bad caps visibly, do you have a DMM to check the voltage rails? You really want to be sure that the power supply board is good before you start messing with the logic board.

I agree with Lucky13, especially after reading you are new to electronics : it would be better if you check voltages first, and replace some caps before, than going to the logic board stuff which, in my opinion, is not the way to go. But it's your call

[bathuu]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Sorry, my bad. It is typo, I meant 713.
I'm newbie to electronics. Just don't know how to check voltages coming from inverter board. I have DMM, If you could enlighten me little bit. Which wires do I need to test? And on settings DMM should be set?
Next, I'm considering to solder 5,6 pin as advised Gonzo.
Cheers cheers, thanks for reply

[lucky13]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

bathuu,

Although there aren't any bad caps visibly, do you have a DMM to check the voltage rails? You really want to be sure that the power supply board is good before you start messing with the logic board.

[EGuevarae]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Thanks for reply guys,
I follow up your advise and see what I can do.
To eguevarae: I could not locate any small cap labelled as 712 on my inverter board. Possibly, my board design is different than yours? Here I attached picture of inverter and logic board.
Cheers

Cap labeled 712? I mentioned mine was a 713, but I was naming the LCD Model : SyncMaster 713. And the board is completely different as mine.

[EGuevarae]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

@eguevarae
you're right, i haven`t read the failure mode accurately. So may be it is indeed another problem the what my Syncmaster have had.
Any way, as the problem is related to signal processing, which is the duty of the same chip, it may be the same cause.

I think it should not hurt any way to solder the resistor. But changing capacitors would certainly would not hurt. Samyoung capacitors do usually not live too long in hot environments.

I agree.