Problems with Samsung 740N monitors

[alexanna]

Re: Problems with Samsung 740N monitors

I would not as a permanent repair your space is going to be very limited, you could try it far as testing goes as long as you stay with the same amperage and voltage.

[Kampfwurst]

Re: Problems with Samsung 740N monitors

Here is my board

http://img833.*************/img833/4456/img2622o.jpg
http://img228.*************/img228/428/img26240.jpg
http://img638.*************/img638/496/img2625i.jpg
http://img831.*************/img831/1236/img2629l.jpg

between the to point from F301 i have 800ohm. I thinks the fuse is gone

[Kampfwurst]

Re: Problems with Samsung 740N monitors

so i tried a glas Fuse. But still nothing. The fuse will not go again. So what can i try.

[retiredcaps]

Re: Problems with Samsung 740N monitors

Here is my board

Please attach clear focused photos using the manage attach feature so they are hosted here and do not post them inline.

Here is an example of the composition of photos we need (top and back side of each board).

https://www.badcaps.net/forum/showpo...94&postcount=1

[aze2learn]

Re: Problems with Samsung 740N monitors

I followed this thread and successfully revived my Samsung 740N after replacing 3 bulging caps 820uf 25v with 1000uf x 3 25v. Had to substitute 3A pico fuse with 3A glass fuse (with fuse cover wired nicely to the board) because I'm unable to find pico fuse here after visiting every local shop near my place. Thank you .. thank you .. thank you for all the guidance

[proffessor]

Re: Problems with Samsung 740N monitors

i copy the picture from another Thread



I replaece the 3 capacitor

where is this fuse. is it the brown one next to the power plug?

The fuse is a 3amp pico fuse.it looks like a resistor but is totally green.You cant see it in your picture because it is hidden under the white glue, near the caps you circled.

[Standstand]

Re: Problems with Samsung 740N monitors

Hi friends!
I have problem with 940N... When I turn it on PC goes normally to windows, and monitor screen stays black, just power button is blinking blue. After 4-5 min desktop appears in some low resolution, so I have to change it manually (up).
This happens ONLY if monitor is cold. It seems like it needs some warm up first...
The same happens even if I turn off PC but no monitor, later, after few hours of pause, it will do the same 'late awakening'. If I turn monitor off when its warmed up and then make short pause, and then turn it on, it works fine. Any ideas, people?

[PlainBill]

Re: Problems with Samsung 740N monitors

Hi friends!
I have problem with 940N... When I turn it on PC goes normally to windows, and monitor screen stays black, just power button is blinking blue. After 4-5 min desktop appears in some low resolution, so I have to change it manually (up).
This happens ONLY if monitor is cold. It seems like it needs some warm up first...
The same happens even if I turn off PC but no monitor, later, after few hours of pause, it will do the same 'late awakening'. If I turn monitor off when its warmed up and then make short pause, and then turn it on, it works fine. Any ideas, people?

Bad caps? ESR drops as a cap warms up. When the monitor was cold it was slow turning on, so Windows didn't detect it, and set the output to a low resolution.

Open it up and look for caps with bulging tops.

PlainBill

[Lord KiRon]

Re: Problems with Samsung 740N monitors

Hi guys,
I have 214T Samsung that first become dim, than after few hours stopped to work at all.
I guess first capacitors are gone, than pico fuse.
I opened it and it looks like 4 capacitors a blown 820uF 25v x2 and 330 uF, 25v x2.
So I got the capacitors and about to solder them in.
However I am not so sure about picofuse, I bought 135V 3A pico fuse , but the problem is that I can't locate it fuse board. I have one "suspect" (greenish thing with black "ring" in the middle) but I am not sure.
How I can be sure? Is there any marking on pico-fuses to distinguish them?

The other question, since I am not specialist in electronics, does pico-fuses have polarity? And if yes, how to tell right one?
The fuses I bough have no marking besides writing "LF 3A" on them.
Can anyone please help me?

[alexanna]

Re: Problems with Samsung 740N monitors

Hi guys,
I have 214T Samsung that first become dim, than after few hours stopped to work at all.
I guess first capacitors are gone, than pico fuse.
I opened it and it looks like 4 capacitors a blown 820uF 25v x2 and 330 uF, 25v x2.
So I got the capacitors and about to solder them in.
However I am not so sure about picofuse, I bought 135V 3A pico fuse , but the problem is that I can't locate it fuse board. I have one "suspect" (greenish thing with black "ring" in the middle) but I am not sure.
How I can be sure? Is there any marking on pico-fuses to distinguish them?

The other question, since I am not specialist in electronics, does pico-fuses have polarity? And if yes, how to tell right one?
The fuses I bough have no marking besides writing "LF 3A" on them.
Can anyone please help me?

I have seen these power supplies with and without a fuse for the inverter. If there is one it's usually hidden around the two schottky diodes under some glue.
Yes the fuses are usually marked on there body,and there is no polarity.

[retiredcaps]

Re: Problems with Samsung 740N monitors

but the problem is that I can't locate it fuse board.

Picofuses are usually marked PF on the PCB. For example, PF801.

PS. A picture of your board would help. Follow the instructions in my sig file below to attach your pictures.

[Lord KiRon]

Re: Problems with Samsung 740N monitors

Picofuses are usually marked PF on the PCB. For example, PF801.

PS. A picture of your board would help. Follow the instructions in my sig file below to attach your pictures.

Thanks.
please review attached images.


As you can see you can clearly see blown caps, but I can't locate pico fuse.

[jetadm123]

Re: Problems with Samsung 740N monitors

Thanks.
please review attached images.


As you can see you can clearly see blown caps, but I can't locate pico fuse.

Nice photos! Your photos justify why we ask for photos of your board. You clearly have 4 bulged caps. Replace the 6 caps, C301,C302,C107,C110,C111 and C112 with good quality caps like panasonic FM or FC series from digikey.com. You can leave the large green Samxon cap alone.

[retiredcaps]

Re: Problems with Samsung 740N monitors

but I can't locate pico fuse.

I don't see one either on the front side. Sometimes a fuse is located on the backside. Check there.

[Lord KiRon]

Re: Problems with Samsung 740N monitors

Thanks guys, replaced the caps and it works.
However somehow it's not too bright , I mean it's not dim like it was before it died, it's rather OK, but brightness 100% gives about same brightness as 40-50% before. Quite usable but this a bit strange.

[jetadm123]

Re: Problems with Samsung 740N monitors

Thanks guys, replaced the caps and it works.
However somehow it's not too bright , I mean it's not dim like it was before it died, it's rather OK, but brightness 100% gives about same brightness as 40-50% before. Quite usable but this a bit strange.

Have you verified all the CCFL's are lit and are at equal brightness?

[skystormfarms]

Re: Problems with Samsung 740N monitors

dose any body see it runs hot

[Lord KiRon]

Re: Problems with Samsung 740N monitors

Have you verified all the CCFL's are lit and are at equal brightness?

The brightness is equal, so I guess all CCFL's are lit.

[miguelangel]

Re: Problems with Samsung 740N monitors

Greetings I had a similar problem to those who are posing here with the 740N model. did not want to turn. will replace the 1000uf capacitors 25volts but not working.The problem was in the small board where is the power button.
Good luck.

[blakmajik]

Re: Problems with Samsung 740N monitors

So after reading over this thread, and replacing both the caps and the fuse, my search lead to shorted fets. I ordered new parts, and now that they have arrived, I can't find the board. I think it's been recycled, I looked everywhere for it.



Any suggestions on a replacement inverter for the 740B? lol