LG 42LB5600 standby light works but no picture and clicking sound

[jmandawg]

Re: LG 42LB5600 standby light works but no picture and clicking sound

I'll help with Diah's English translation. The TV will power on with the panel disconnected and you can watch the LEDs flash to see which one is not lighting up. You can record it on video and go frame by frame if it is too quick.

I will add with LED problems, it is better to replace all the strips with new. They all have wear and the ones still working are likely to fail. With the LB series, the heavy lenses also tend to fall off with age.

Here is a good analogy. My right side low beam burnt out on my car so I replaced it but bought a spare since I expected the left side to go as well. Sure enough, a couple of months later the left side went. My daytime running lights have more hours on them and use the same bulbs but I don't expect them to fail. Why not? Because they run dimmed around 40% of maximum. Same thing applies with LED backlights except of having 2 bulbs, you have a string of many.

Ok that makes sense. Not sure if it's worth investing in new LEDs or not with a TV this old and i did bend the frame a little when removing it... Was hoping it was something easier/cheaper. Thanks for all the help guys.

[neilc6]

Re: LG 42LB5600 standby light works but no picture and clicking sound

New strips are only $20 to $30 from China (search ebay). Not too difficult to replace on a 42 inch but they are stuck down pretty good. Need to use a scraper with a hammer to knock them out but you end up popping off every lens as well.

If a LED fails open in the string, they will not flash. You can use a multimeter in diode test mode to test each LED. You need to scrape off the soldermask to contact the copper underneath.

[jmandawg]

Re: LG 42LB5600 standby light works but no picture and clicking sound

Thanks i may give it a try. On a side note, can anyone recommend a good inexpensive variable power supply? It would probably come in handy testing these LED strips etc.

[budm]

Re: LG 42LB5600 standby light works but no picture and clicking sound

Before giving up.
1) In your post #1
"I do get voltages across the fuses and the large caps (did not check the small ones) but no voltage out the led power (top red and black wires). " What did you use for ground ref. for the meter to check the LED Voltage at the LED connector?

2) C224 is the LED power supply filter cap, the Voltage from this cap is fed to the Boost converter to boost the Voltage higher (208V as printed on the board) to drive the LED string. So if you use black meter probe on the chassis and Red probe on the LED + pin of the LED connector, LED connector must be in place and the board must be mounted to the chassis), you should see the same Voltage as you see on the C224. Please check that. BTW, C224 is rated at 160V so you are getting higher Voltage than rating, I hope that is just measurement error.

3) Since LEDS are connected in series so if one or more LED shorted out the good LED'S should flash on for second before the protection circuit kicks in. Did you see the backlights even flash on for seconds when you turn the TV on? I will not be surprised if it had bad LED issue but at least like to get correct Voltage reading for future ref.

4) BTW: "I do get voltages across the fuses" you should not get any Voltage reading across the fuse (measured between the two ends of the fuse) because fuse basically is a short circuit (with the exception of very very low current rating fuse) so there should be no Voltage drops across the fuse.

[jmandawg]

Re: LG 42LB5600 standby light works but no picture and clicking sound

Before giving up.
1) In your post #1
"I do get voltages across the fuses and the large caps (did not check the small ones) but no voltage out the led power (top red and black wires). " What did you use for ground ref. for the meter to check the LED Voltage at the LED connector?

2) C224 is the LED power supply filter cap, the Voltage from this cap is fed to the Boost converter to boost the Voltage higher (208V as printed on the board) to drive the LED string. So if you use black meter probe on the chassis and Red probe on the LED + pin of the LED connector, LED connector must be in place and the board must be mounted to the chassis), you should see the same Voltage as you see on the C224. Please check that. BTW, C224 is rated at 160V so you are getting higher Voltage than rating, I hope that is just measurement error.

3) Since LEDS are connected in series so if one or more LED shorted out the good LED'S should flash on for second before the protection circuit kicks in. Did you see the backlights even flash on for seconds when you turn the TV on?

4) BTW: "I do get voltages across the fuses" you should not get any Voltage reading across the fuse (measured between the two ends of the fuse) because fuse basically is a short circuit (with the exception of very very low current rating fuse) so there should be no Voltage drops across the fuse.

1+2) Your right. I measured the red led wire with the chasis, and it's getting 103v, i measured C224 again and it is also 103v (i don't think board was screwed in before or maybe leds weren't hooked up don't remember).

3) i did not but let me try again when it gets dark the room it is in has a lot of windows.

4) again you are right, i meant there is 0 resistence.

Oh and before when i previously said the 24v pin was dropping from like 18v to 1, it's because my meter was set to 20v and overvoltage makes it show one when i set it to a higher voltage it show 24v. Sorry i'm still a noob.

edit #2: they do flash real quick, i turned it upside down and lifted it slightly and peeked under and i saw them flash for half a second, sorry i'm an super noob I will try to video and see which one is failing.

[budm]

Re: LG 42LB5600 standby light works but no picture and clicking sound

1+2) Your right. I measured the red led wire with the chasis, and it's getting 103v, i measured C224 again and it is also 103v (i don't think board was screwed in before or maybe leds weren't hooked up don't remember).

3) i did not but let me try again when it gets dark the room it is in has a lot of windows.

4) again you are right, i meant there is 0 resistence.

Oh and before when i previously said the 24v pin was dropping from like 18v to 1, it's because my meter was set to 20v and overvoltage makes it show one when i set it to a higher voltage it show 24v. Sorry i'm still a noob.

edit #2: they do flash real quick, i turned it upside down and lifted it slightly and peeked under and i saw them flash for half a second, sorry i'm an super noob I will try to video and see which one is failing.

Good, we at least get the correct data.
That 24V is on its own it is turned on by the PS-ON signal from the main board (you can see how it is being controlled by looking at the bottom side of the board), it not controlled by the backlights circuit.
103V feeding the boost converter is about right.
So, yeah at this point you can learn how to replace LED strips, it'll be good learning experience.

[jmandawg]

Re: LG 42LB5600 standby light works but no picture and clicking sound

I'm going to order these off ebay. Will report back when they get here.

https://www.ebay.com/itm/8-PCS-set-L...B/274440811135

[vinceroger69]

Re: LG 42LB5600 standby light works but no picture and clicking sound

this video will give you idea on how too change the led strips
https://www.youtube.com/watch?v=QPYtCz9xWWA&t=1014s

[jmandawg]

Re: LG 42LB5600 standby light works but no picture and clicking sound

this video will give you idea on how too change the led strips
https://www.youtube.com/watch?v=QPYtCz9xWWA&t=1014s

That's a great video, i wish i saw it a couple days ago. Does it matter if the old white tape that sits between the frame and the LED strip is removed with the old led strips? The tape on mine is coming off easier than the led strips so it's easier to just pull the tape off with the led strips. So can i attach the new LEDs directly to the frame or is the tape needed to providing some kind of insulation.

[budm]

Re: LG 42LB5600 standby light works but no picture and clicking sound

BTW, make sure to take the pictures and mark how the layer of all the sheets go together and the direction of how that go together.

[vinceroger69]

Re: LG 42LB5600 standby light works but no picture and clicking sound

That's a great video, i wish i saw it a couple days ago. Does it matter if the old white tape that sits between the frame and the LED strip is removed with the old led strips? The tape on mine is coming off easier than the led strips so it's easier to just pull the tape off with the led strips. So can i attach the new LEDs directly to the frame or is the tape needed to providing some kind of insulation.

if it comes of the frame its ok as the new strips have new tape on them usually its hard too get of the frame so we sometimes just leave it on like in the video.