UN48JU6400 LEDS lightly flicker but won't stay on

[lfhlaw]

I've lurked on these boards for a while and learned a lot. However, I'm having issues with a UN48JU6400 Power Supply board.

When I power it on, the LEDS will flick briefly with very little light and go out. I've tested the LEDs with a LED tester and there are no blown LEDs.
I've replaced the cable going from the PSU to the LED strips with no improvement.

Also when I do power it on, the LED will blink 4-5 times.

I've looked over the PS Board and there are no noticeable blown Caps.
I've also bought a replacement board with no improvement to the LEDs lighting up. So Either I have 2 bad Power supply boards or something else is up with the boards that is not visible.

I do have a Multimeter but not sure where to start.

and I'm not good at reading Schematics.

[budm]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

"When I power it on, the LEDS will flick briefly with very little light and go out. I've tested the LEDs with a LED tester and there are no blown LEDs." So Voltage does it show on your tester? Since LED strings are connected in series if you have shorted LEDs, the strips will still light up.

[budm]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

Is this your board?
Samsung BN96-35336A Power Supply
http://www.shopjimmy.com/samsung-bn9...wer-supply.htm

[budm]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

You need to teat the Voltage at each pin of the LED connector EVERY TIME you turn on the TV to see how high the Voltage jumps up to and how low it goes down to after 10 seconds, you will have to do that 4 times with LED connector in place and 4 times without LED connector in place because you have 4 wires on that LED connector, you must follow the instructions.
You will have to leave Black probe on the chassis and red probe on each pin each time.

[lfhlaw]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

Is this your board?
Samsung BN96-35336A Power Supply
http://www.shopjimmy.com/samsung-bn9...wer-supply.htm

Yes

[budm]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

So do the test as in post 4.

[lfhlaw]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

"When I power it on, the LEDS will flick briefly with very little light and go out. I've tested the LEDs with a LED tester and there are no blown LEDs." So Voltage does it show on your tester? Since LED strings are connected in series if you have shorted LEDs, the strips will still light up.

Yes the LED tester is from ShopJimmy.
it reads 29.7 Volts for each LED strip. Starts at about 27 volts and ramps up to about 29.6-29.7 Volts.

[lfhlaw]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

You need to teat the Voltage at each pin of the LED connector EVERY TIME you turn on the TV to see how high the Voltage jumps up to and how low it goes down to after 10 seconds, you will have to do that 4 times with LED connector in place and 4 times without LED connector in place because you have 4 wires on that LED connector, you must follow the instructions.
You will have to leave Black probe on the chassis and red probe on each pin each time.

By LED connector in place and without it in place, I've tested it with the connectors in place. Out of place....Where am I Putting the Multimeter? on the PS Board pin? or just unplugging the LED Connector from the Plug to the Lights and still testing the Same spot on the LED connector?

Also, Here's what I got from testing with the LED Connector in place. One of the Wires(The blue one) only goes to about 114 Volts when powered on. The others all went to about 296 Volts.

Interestingly, When I use the multimeter to test the wires, the lights came on full power.

[lfhlaw]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

Ok Testing the LED Connector not connected to Lights. The 1st wire (pictured) goes Out of limits for my Multi meter when powered on. When I Turn TV off, the Voltage drops down to about 240 volts and stays there. The other 3 LED wires produce a 0 Voltage which I'm guessing would make sense since the power is in series and guessing the 1st wire powers the other 3.

[lfhlaw]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

By LED connector in place and without it in place, I've tested it with the connectors in place. Out of place....Where am I Putting the Multimeter? on the PS Board pin? or just unplugging the LED Connector from the Plug to the Lights and still testing the Same spot on the LED connector?

Also, Here's what I got from testing with the LED Connector in place. One of the Wires(The blue one) only goes to about 114 Volts when powered on. The others all went to about 296 Volts.

Interestingly, When I use the multimeter to test the wires, the lights came on full power.

Also initially when powered on, the power spikes to about 600 volts then drops to 296 volts for each of those wires aside from the blue wire.

[budm]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

1) Please look at the LED connector pin chart as printed on the board, you can see pin names: 1+, 1-, 2+, and 2 -.
2) Put the LED connector back in place and retest those 4 pins again as instructed before, but this time report the pin name and pin number for each pin.
3) "Interestingly, When I use the multimeter to test the wires, the lights came on full power." That means the female connector is not making good contact with the male pin on the board, so inspect the wire termination on the female end and on the male pins which are soldered to the board. The female sockets on the connector may have been expanded too much so it causes poor connection to the male pins.
4) When you use tester to test the LED you need to test the whole string, means you put the tester on the female pin of the connector to test each LED string, I.E LED string # 1 by putting the tester in 1+ and 1 -, 2+ and 2 -.

[lfhlaw]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

UGH. Lol turns out, the connector was bad. I replaced it with another i had. And this time the LED lights worked. IDK I thought I had done it before, but who knows.

so put it all back together. functioning as well as can be.
thank you for the help sir.

[budm]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

Thanks for the follow-up.

[bigdog8882]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

Just unplug the connector from PS to main. If the Backlights light up and stay lit then you may have a mainboard issue. Then U have to unplug the T-con from mainboard and troubleshoot down to the panel which means unplugging the 2 ribbon cables going to the driver boards or panel from the bottom of the t-con board to see if the tv BL's stay lit.

[budm]

Re: UN48JU6400 LEDS lightly flicker but won't stay on

This is old thread, the problem is already fixed.