Samsung UE32F5000AK sound ok, no picture.

[macwireworld]

Hi,

I have a 15 month old 32" Samsung TV which didn't produce any picture this morning. The sound is fine, I can change channel and turn the sound up and down via the remote without any problem at all.

However, there is no picture, the set used to flash up a Samsung logo when it was turned on, now nothing at all.

I can solder and use a multimeter but this is my first attempt at TV repair so any help or pointers would certainly be appreciated.

I'm happy to post any pics to help and I'm keen to learn.

Kind regards

Mac

[tom66]

Re: Samsung UE32F5000AK sound ok, no picture.

Can you check and see if the screen still has a faint glow when turned on?

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

Hi Tom,

Thanks for the reply.

I've just tested it in a pitch black room. When I press the power on on the remote, (this set has no actual on/off switch), the red led blinks on and off 6 times (it did that before the picture was lost) and just for a briefest of moments a very dim white flash appears in the middle of the screen, the flash doesn't fill the whole screen, it covers about 4 - 6 inches of it just in the centre.

Kind regards

Mac

[tom66]

Re: Samsung UE32F5000AK sound ok, no picture.

My first guess would be an open circuit LED in the panel. A second guess would be an issue with the power supply's LED driver circuit. Could you take the back cover off and get some nice clear photos of the parts inside the set?

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

double post..

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

Hi Tom,

Please see attached photos, I'll take a good look at the boards tonight using a big magnifying glass to see if anything looks kaput or blown.

When the set has power there are 3 blue led lit on the middle bottom board.

Kind regards

Mac

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

and a few more...

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

Bugger! No sign of anything obvious on first inspection, all looks ok...

[Shinju]

Re: Samsung UE32F5000AK sound ok, no picture.

Unplug the mainboard harness from the Powersupply and see if the backlights kick on. Unplug the unit from power, then unplug the main from the PS then plug the unit back in.

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

Unplug the mainboard harness from the Powersupply and see if the backlights kick on. Unplug the unit from power, then unplug the main from the PS then plug the unit back in.

Hi Shinju, please take a look at the photo to see if I got it right.

Many thanks

[Shinju]

Re: Samsung UE32F5000AK sound ok, no picture.

The top cable is the correct one, so you get nothing? The flat ribbon cable is the LVDS cable to the T-Con.

So try disconnecting the LVDS cable (leave the mainboard/power supply cable intact) and then try turning on the unit.

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

With the top cable disconnected, the whole set powers off, cant use the remote, no led's lit on the T-Con... this set doesn't have a on/off button at all, it's dead.

With the LVDS cable disconnected and the set powered on with the top power cable connected, exactly the same as before, six blinks of the standby red LED and nothing just a blank, dead screen.

[Shinju]

Re: Samsung UE32F5000AK sound ok, no picture.

Sounds like you have a short in a LED strip or a problem with the PS like Tom66 had suggested.

Time to get diry! going to have to test each strip and get some readings off the PS. I have not had one with a shorted LED strip so I cannot help any further but since your panel is only 32" it shouldn't be that bad to take the LCD screen off to get to the strips.

Someone will come and help you further!

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

Someone will come and help you further!

Thanks for your help Shinju, I'm now a man on a mission

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

I've just tested the voltages from the power board to the main board and I think they look ok, (Picture1).

What I did find weird was the power board to screen (picture2) has one pin with 196 - 225 volts (keeps dropping and climbing) running from it... is that right? I thought the cold part of the power board was low voltage.

[budm]

Re: Samsung UE32F5000AK sound ok, no picture.

From what I can see from the pictures, you have 4 strings of LEDs (+/1, +/-2, +/-3, and +/-4, + is the Anode side of the led string, - is the Cathode side of the string)
So check the Voltage on each pair of the connector and see which one gives you the highest Voltage reading, that will be the one with open LED/LEDs on that string.
So it looks like string #1 has open circuit.
This is what I use to find out which string has open circuit (RED LED will not flash on).
https://www.badcaps.net/forum/showpo...&postcount=107
I am sure if this one has one of those training manual on how to force on each LED string or not, I saw that some where in the thread.

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

Thanks for the reply, bit the bullet and stripped down the screen and found the problem!!!

Looks like a component (see pic) has blown on one strip, all the other strips look fine. Any advice on how to fix or do I need to buy a new strip? I'm not sure what you call the broken bit

[budm]

Re: Samsung UE32F5000AK sound ok, no picture.

I cannot tell what that is, but since you have other strip, can you test and see how they are measured in Ohms, and trace out how they are connected to the + and -?
It must be connected in series withe LEDs and that is why it acts like open LED string symptom.

[macwireworld]

Re: Samsung UE32F5000AK sound ok, no picture.

I'm going to try to bridge the connection with solder, the resistor has turned to a white powder as seen it the pic above, when I touched it it crumbled away, all I have there now is a gap where the resistor was and it looks ok to solder.

Do you think I'll damage anything if I try this?

Kind regards

Mac

[tom66]

Re: Samsung UE32F5000AK sound ok, no picture.

Do you think I'll damage anything if I try this?

It could be a fuse - doing so could damage something else. I think you should think about why it failed rather than just bridging it. Resistors rarely fail for no obvious reason.