Samsung 710

[pctek]

Samsung 710 when opened chasis found 3 buldged capacitors . 2x 1000uF , 1x 330uF (circled in red on picture 1). After recap , a ticking sound is heard and power light flashes on/off rapidly . Any help ?

[budm]

Re: Samsung 710

It can be shorted circuits so it goes into shutdown/restarting mode, or it may have bad start-up cap (small cap by the large filter cap in the primary side, may something around 22~47uF 50Vdc).
By the way, the 3 caps you replaced are for the backlights inverter circuits, there are two more small caps by the inverter transformers also. The other caps by the top right of the board are for 5VDC power supply for the logic board. They should all be repalced with good low ESR caps such as Panasonic FM/FR/FC series. Bad cap can look normal but can have high ESR, you will need ESR meter to test that.

[pctek]

Re: Samsung 710

Thank you for your help . Will order and replace the remaining caps and post the result.

[eknas]

Re: Samsung 710

I know its been a while since this thread but.. Did you fixed by replacing all caps? I have this display with similar trouble so I would like to know how you ended it.

[selldoor]

Re: Samsung 710

eknas - it is a long while since pctek posted anything. You will be better posting posting
pictures of your boards and telling us what your monitor does.
Do you have a multimeter and have you done any testing. ( On this or an anything)

[eknas]

Re: Samsung 710

I appreciate very much your help.
First of all, when I turned on my monitor it tried to switch on, and stoped, with the power light alternating on/off just like when the computer was off or at saving power mode. When disconected the VGA wire the screen showed the message that it was unplugged.

I opened it and found like pctek, those 3 same caps at bad state. In my case they were 2x 820uF and 1x330uF. The shopkeeper told me to use 1000uF caps instead (he didnt have 820uF at that moment) if they were for a power source. So after recap with them, it happened just like the op, ticking sound was heard and power light flashing on/off fast.

I managed to get the 820uF caps in another shop and I recaped again. The power led ticked fast again, with the sound, but this time a SMD burnt as the pic I show.

I think that was a transistor that would be shorted, wasnt it? There are no more transistors at the inverters zone but Im not sure. Could you confirm this?

[selldoor]

Re: Samsung 710

Ok - picture is not really clear enough - we need to be able to read the part
numbers on the board. I cant see which component is damaged. We also need the other side of the board.
Please post using Manage attachments so the pictures stay on this site.
If there is time you may as well try to EDIT your post and remove the picture.

EDIT - spotted the burnt transistor - it is one of the mosfets that drives the inverter. Can you still read the number on it or even part of the number.

[eknas]

Re: Samsung 710

Ok, I will change the host of the image. The U204 is the burnt one. I found a magnifying glass and the U205 and U204 are both SP8M3.

I also upload the other side pic. As you can see, the bad caps are removed at this moment.

[selldoor]

Re: Samsung 710

Here is the data sheet
http://html.alldatasheet.com/html-pd...4/1/SP8M3.html

Available on ebay
http://www.ebay.es/itm/5pcs-SP8M3-SP.../271358267815?
pt=LH_DefaultDomain_0&hash=item3f2e3691a7


We usually suggest replacing them in pairs

ALSO read post 2 again this part:
"They should all be replaced with good low ESR caps such as Panasonic FM/FR/FC series"
Is important.
You will be ok with 1000uf or 820uf but they MUST be low esr or the new mosfets will not last long

[eknas]

Re: Samsung 710

Ok, thanks for your help. I will try do as you say, but it seems to be quite hard to weld..

Anyway, my doubt is based in the chronology of how this happened..

To sum up:
1. The monitor does not show image from VGA, but when the VGA cable is unplugged, the screen showed the message that the cable was not conected. (I smell it comes from video board)
2. I open and replace the caps that are at bad state at a simple look, for 1000uf caps at the power board. When turn on, the power led blinks fast.
3. I change the 1000uf for the 820uf caps. I turn the screen on and same fast blinkin but after a while, the transistor burns..

So what I think is that there might be another trouble, in witch the video board could be involved as I changed the caps the first time and the transistor did not burn that time.

What do you think?

Anyway, on Tuesday I will go to the store to gather the stuff and try to weld the transistor.. I have already watched some welding SMD tutorials

[selldoor]

Re: Samsung 710

You could be correct but without a working power supply its difficult to test anything else.
Did you check the caps are right way round?
Also check for solder bridges or damages traces

[eknas]

Re: Samsung 710

I checked the caps for sure, it was the first thing I did hehe.
I am going to see some vids to be able to check for solder bridges because apparently they are all right but I don't know how they look damaged.

Again, thank you very much. I will post the advances, I hope this week, luckly sooner than pctek

[viziks]

Re: Samsung 710

I have just fixed 2 such monitors and in both cases mains filter (100uf 450V Capxon KM ) were defective. Problem was Pix came for a second and then powers off then on again repetitively. Check voltage across capacitor should be 320V stable if you have 240V supply.

[eknas]

Re: Samsung 710

I have a total noob question. Should I check the voltage in DC or AC? My multimeter does not give me too much confidence but I have taken 320V stable at DC.., so I will buy the transistor as soon as possible and resold it.

Thanks for your words

[selldoor]

Re: Samsung 710

Yes the voltage at the big cap is vDC

[eknas]

Re: Samsung 710

I have received today the smd transistor. I have tried to replace it follwing some smd soldering tutorial on youtube but the result has been terrible.

At some point I turned the monitor on and it showed the image for less than a second, so I kept trying to solder better the inversor transistor but I didnt get it.

Possibly my next move will be to order the ip 35135a board to China as it is not very expensive.

Thank you all for all messages

[selldoor]

Re: Samsung 710

Thanks for the update - let us know how you go on if you get a new board.
Keep the old one for spares? or offer on freecycle

[eknas]

Re: Samsung 710

Finally I have received the board pretty fast compared to the transistors. In 3 secs I have mounted it and It has worked perfectly.

If someone in the future wants to know the store where I bought it feel free to send me a PM, though its pretty easy to find one by searching the board model, IP-35135A, in ebay or these chinese e-stores.

Thank you all for your support guys.

Yes selldoor, I will keep the old one for spares.

[dj2009]

Re: Samsung 710

Hello all,
I know it is quite some time since this thread was active.
I have a problem similar to the problem ekans had mentioned. Monitor LED would blink with a normal speed and no picture (not even showing the "cable unpluged" messagge). After opening it up, I noticed those 3 caps (C111,C112: 820uF and C302:330uF) had bulged. I replaced those with same spec caps but now the monitor LED blinks very fast.
Nothing else seems to be blown by visual inspection of both sides of the board.
Can anyone instruct on the troubleshooting procedure?

Thanks

[dj2009]

Re: Samsung 710

Forgot to mention that the board is IP-35135A.

Hello all,
I know it is quite some time since this thread was active.
I have a problem similar to the problem ekans had mentioned. Monitor LED would blink with a normal speed and no picture (not even showing the "cable unpluged" messagge). After opening it up, I noticed those 3 caps (C111,C112: 820uF and C302:330uF) had bulged. I replaced those with same spec caps but now the monitor LED blinks very fast.
Nothing else seems to be blown by visual inspection of both sides of the board.
Can anyone instruct on the troubleshooting procedure?

Thanks