Emerson LF501EM4F turn on then off.

[hmendez86]

Re: Emerson LF501EM4F turn on then off.

did you replace the leds, all of them. i had the same problem i replace all leds strips and it works u need a old led tv get somes strips of leds and try to install them. your problem is there but you need to figure it out how to plug new leds from other tv.

[Trent]

Re: Emerson LF501EM4F turn on then off.

Just started having this same issue. The logo, the long start, the speakers popping abrupt shutdown...

Well crap. Same symptoms - but after the painful effort of taking mine apart - all the LEDs work and are super bright. My issue is somewhere else.

I accidentally ripped the left-most ribbon off the LCD screen when removing it too. I'm officially in too deep. I plan to take pictures and start a different thread when I get things back together.

I read online that dark spots on PCB boards are common around resistors that put out a lot of heat - but I'm guessing that the power board needs to be replaced. All the capacitors look fine- but without pictures - I don't expect many replies. I'll get updates as soon as I can find a decent camera.

[dick_barton]

Re: Emerson LF501EM4F turn on then off.

This is how I remove the old LEDs:
https://www.badcaps.net/forum/showth...053#post657053

Very neat way to remove them. I'll have to remember this method.

[CapLeaker]

Re: Emerson LF501EM4F turn on then off.

good luck!

[Trent]

Re: Emerson LF501EM4F turn on then off.

Just started having this same issue. The logo, the long start, the speakers popping abrupt shutdown...

Thanks for taking pictures! About to open mine up.

[budm]

Re: Emerson LF501EM4F turn on then off.

This is how I remove the old LEDs:
https://www.badcaps.net/forum/showth...053#post657053

[SLK001]

Re: Emerson LF501EM4F turn on then off.

Measure the LED's dimensions with a set of calipers (in MM) while still on the board. It looks like the big pad is going to be an ANODE. They look like LG 100LM series.

It's best to remove the LED with two soldering irons. Do you have two?

First, use the hair dryer to heat the board to around 150F. Apply excess 63/37 solder to the two pads, then, with one iron on one side and one iron on the other side, melt the solder and using the two irons as one, slide the LED off the pad and onto the white area. Take a GOOD picture once this is completed.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

I'm guessing the black stuff is the glue!
But I got it off.
Here is a picture

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

Is the photo from your set? If so, how did you get it to light?

Since the LED string is a series circuit, the LED marked "B" would have had to shorted out - a rare occurance.

Anyway, use a hair dryer to soften the glue on the lens, then slide a slot screwdriver under the lens and pop it off. Remove as much of the glue as you can while it is still soft.

Take good high resolution photos of the LED and post them here.

Yea the photo is from my set. Sometimes it doesn't come on I have to unplug and plug it back in for it to come on. When I does 10 or 15 seconds later that one led will light up too. But I do have to unplug one of the other good strip for it to work if not the lights go crazy on off on off on off.

[SLK001]

Re: Emerson LF501EM4F turn on then off.

Is the photo from your set? If so, how did you get it to light?

Since the LED string is a series circuit, the LED marked "B" would have had to shorted out - a rare occurance.

Anyway, use a hair dryer to soften the glue on the lens, then slide a slot screwdriver under the lens and pop it off. Remove as much of the glue as you can while it is still soft.

Take good high resolution photos of the LED and post them here.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

O i can repair the LEDS! I didn't know Ithat was possible. Yes most definitely repair it.

[SLK001]

Re: Emerson LF501EM4F turn on then off.

You have to match the polarity of the LED you select with the polarity of the pad. Samsung LEDs are mostly CATHODE on the large pad. LG LEDs are mostly ANODE on the large pad.

If you don't want to attempt a component level repair, then just buy the strips. I will probably cost you ~$60. If you attempt a component repair, the LEDs will cost you <$10.

It's up to you.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

Well I do know one strip of L.E.D'S are bad do I really need to test them?
I did find a set on ebay. But they are Samsung and mine are LG. but I would change them all out to the Samsung one's. The auction does say they are from LF501EM4F.
Would I have a problem if I changed them all?

[SLK001]

Re: Emerson LF501EM4F turn on then off.

You can probe for which terminal is which by using your ohmmeter. Touch one lead to the (+) terminal on the connector and use the other to find out which side of the LED is the anode.

Since there may be a protection diode on the chip, you are looking for a zero voltage drop (or close to it).

[budm]

Re: Emerson LF501EM4F turn on then off.

Be careful when testing LED without current limiter power supply if you apply the Voltage to wrong terminal of the LED that has internal protection diode.
https://www.badcaps.net/forum/showth...996#post656996

You can see what happen by having Amp meter connected in series with power source.

[SLK001]

Re: Emerson LF501EM4F turn on then off.

Take a power supply dialed to 3 volts. Clip a short piece of thin wire (~24 ga) to each lead and slide the wire under the lens, making contact on each end of the LED. You will have to guess on which side is positive and negative and what is the orientation of the diode. However, finding that is pretty easy and quick. Once one diode lights up, proceed down the strip, marking all those that do NOT light up.

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

No not sure on how to test it. I seen what strip is having the problem but there are 2 boards on the strip.

[SLK001]

Re: Emerson LF501EM4F turn on then off.

Have you identified the bad LEDs yet?

[erickeri1234]

Re: Emerson LF501EM4F turn on then off.

Samsung LEDs usually have the cathode on the larger pad. LG LEDs usually have the anode on the larger pad. DO NOT modify the pads to fit one where the other should go. The pads are the primary heatsink for the LEDs, which are usually driven to the max, thus requiring all the heatsinking that they can get.

At the head of the strip, you should see a (+) and a (-) and two small test points. Use your ohmmeter to determine which pad is which.

Pic

[SLK001]

Re: Emerson LF501EM4F turn on then off.

Samsung LEDs usually have the cathode on the larger pad. LG LEDs usually have the anode on the larger pad. DO NOT modify the pads to fit one where the other should go. The pads are the primary heatsink for the LEDs, which are usually driven to the max, thus requiring all the heatsinking that they can get.

At the head of the strip, you should see a (+) and a (-) and two small test points. Use your ohmmeter to determine which pad is which.