Smasung SyncMaster 913N Monitor wouldnot display images

[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

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

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

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

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

[Bobdee]

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

Hello Daniel
Just a suggestion
Set meter to Diode test (2K ohms)
Take readings as Bill suggested then reverse probes and take them again
Each chip has two Mosfets a P channel and a N channel mosfet, so the one half is taken pos readings and the other half neg
Shorts do not always show up when testing in circuit so the reading are the important part, to compare one chip to the other
The only sure way to test is out of circuit

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Guys,

Thanks for your replies. When I took those readings the DMM was set to 2000K and I did try swapping post/neg terminals. I have taken a new set of readings with the DIODE test feature selected on the DMM and they are below:

top right ic:

1-2 602
1-8 1.786 - however it was climbing by one every few seconds
2-8 1.998 - then it resets back to 0
3-4 721
3-5 488
4-5 1.992 - then resets back to 0

bottem right ic

1-2 1.420
1-8 1.787 - however it was climbing by one every few seconds
2-8 1.999 - then it resets back to 0
3-4 720
3-5 487
4-5 1.997 then resets back to 0

I've attached a photo of the DMM.

Daniel

[PlainBill]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Guys,

Thanks for your replies. When I took those readings the DMM was set to 2000K and I did try swapping post/neg terminals. I have taken a new set of readings with the DIODE test feature selected on the DMM and they are below:

top right ic:

1-2 602
1-8 1.786 - however it was climbing by one every few seconds
2-8 1.998 - then it resets back to 0
3-4 721
3-5 488
4-5 1.992 - then resets back to 0

bottem right ic

1-2 1.420
1-8 1.787 - however it was climbing by one every few seconds
2-8 1.999 - then it resets back to 0
3-4 720
3-5 487
4-5 1.997 then resets back to 0

I've attached a photo of the DMM.

Daniel

I'd say that neither of these is shorted. At this point you have two options. You can try this power supply / inverter in one of the working monitors. Or you can replace all 11 of the capacitors I've circled in the attached picture.

Incidentally, some of the results you got were distorted because the meter was putting out sufficient voltage to turn on (at least partially) the FET. The resistance scales use a lower voltage and do not cause a semiconductor to conduct. I prefer to use the 200 ohm scale; that will clearly show the difference between a shorted and unshorted transistor. The diode scale is great for checking diodes and bipolar transistors.

PlainBill

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

PlainBill,

Thanks for your reply. I tested another power supply from a working monitor and the non working monitor came to life and displayed a picture. I'll replace those capacitors.

Daniel

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

I have now compiled a list of caps that need changing. A couple are manufactured by Sam Young, does it make a difference if I just do a straight swap with another brand? Also where's the best place to buy these caps from?

25v 70uF
47uF 35v
4.7uF 50v
22uF 50v
47uF 35v
22uF 50v
470uF 25v
470uF 25v
1000uF 16v
330uF 25v
330uf 25V

Daniel

[PlainBill]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

I have now compiled a list of caps that need changing. A couple are manufactured by Sam Young, does it make a difference if I just do a straight swap with another brand? Also where's the best place to buy these caps from?

25v 70uF
47uF 35v
4.7uF 50v
22uF 50v
47uF 35v
22uF 50v
470uF 25v
470uF 25v
1000uF 16v
330uF 25v
330uf 25V

Daniel

Check that value, very non-standard.

If you're in the USA I prefer to use Digikey. Their First Class mail delivery option is inexpensive and fast. I've written a tutorial on selecting the proper replacements. Don't go with the original brands; they suck.

I prefer Panasonic FM or FC series, but other quality brands (Rubycon, United Chemicon, others) have as good or better series of caps. Above all, compare the dimensions of the originals to the replacements. Speaking from experience, it's embarrassing when the monitor works but you can't get it back together because a replacement cap is too tall.

PlainBill

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

PlainBill,

I checked the cap again and its 470uF there was a load of white sealent type of stuff on it. Unfortunently I am based in the UK so I'll have to find a supplier over here. I'll definitely check the dimensions before buying you've got a valid point there. Hopefully this fixes the problem because as I said I have three other samsung 913n monitors and it would be annoying not knowing how to fix them if it happened again.

Many thanks once again. I'll port my results, it may or may not help someone else.

Daniel

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

For some of the cap replacements I cannot get the original voltage but the correct uF so can I use for example a 470uF 35v in replacement for a 470uF 25v and so on?

Daniel

[Krankshaft]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Yes the voltage is only the max working voltage the cap can handle as long as the caps will fit. You can always go slightly higher but never lower.

Please note if you went up a ridiculous value in working voltage the ESR would also be higher as well. The higher the WV the higher the ESR for the given capacitance.

But the voltage difference would need to be much higher for the ESR to be a consequence. Most likely the cap wouldn't even fit on the PCB.

[PlainBill]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

PlainBill,

I checked the cap again and its 470uF there was a load of white sealent type of stuff on it. Unfortunently I am based in the UK so I'll have to find a supplier over here. I'll definitely check the dimensions before buying you've got a valid point there. Hopefully this fixes the problem because as I said I have three other samsung 913n monitors and it would be annoying not knowing how to fix them if it happened again.

Many thanks once again. I'll port my results, it may or may not help someone else.

Daniel

There are several regulars who are in the UK. Bobdee comes to mind. The may know UK sources.

PlainBill

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Thanks guys. I'm going to swap the capacitors this evening probably 17:33 UK time.

Daniel

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

Hi,

Well I replaced all the caps circled in brown as instructed to by PlainBill however I didn't manage to replace the top left (16v 1000uF) due to it not being in stock or the really big one. I'll order those and replace I suppose it could be either one of those caps that has gone which is causing this.

Daniel

[gonzo0815]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

As time goes, the problem with this monitor is indentified. It is the NT68F63L controler, wich failes. There is no solution to this except replacing. Even reprogramming the firmware does not help. It is simply a age related failure of this IC. Sadly enough, i have not found any reseller of this chip, with the exception of a chinese one. Chip item costs 4.6US$ but shipping to germany is abouth 29$ so that an economic repair.

Edit: for you US guys this ma y be interesting for you:
http://stores.shop.ebay.de/AnBparts_...95145QQ_sopZ10

they sell it fore abouth 6US$ incl. shipping.

[dan86]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

gonzo0815,

I see. I am about to replace another capacitor that I didn't manage to last night due to not having a replacement and then I just need to replace the bigger one. If it still doesn't work then I will leave this because I may aswell just buy a screen for £80. Also I am not amazing with a soldering iron and replacing the bigger IC on the underside of that board doesn't look like a fun thing todo to me.

I had a look on that ebay link and searched or NT68F63L and it displayed a few chips which would NOT fit as a replacement to the ones located on the underside which I mentioned above. I did try and source a supplier for the entire psu but haven't found anyone yet.

Daniel

[Bobdee]

Re: Smasung SyncMaster 913N Monitor wouldnot display images

As time goes, the problem with this monitor is indentified. It is the NT68F63L controler, wich failes. There is no solution to this except replacing. Even reprogramming the firmware does not help. It is simply a age related failure of this IC. Sadly enough, i have not found any reseller of this chip, with the exception of a chinese one. Chip item costs 4.6US$ but shipping to germany is abouth 29$ so that an economic repair.

Edit: for you US guys this ma y be interesting for you:
http://stores.shop.ebay.de/AnBparts_...95145QQ_sopZ10

they sell it fore abouth 6US$ incl. shipping.

Thanks gonzo0815
Good info and update to the problem
Can you tell us if this part is already programed???
Also Dozy me removed the sticker on the said IC when I was looking for info off it, and binned it (2 monitors) is there anyway now of telling which one of the 5 that they sell, that I need now???
Any thoughts on how I can get over that
Many Thanks
Bob