Samsung UN65J6200AFXZA No backlight

[high-tech]

hi everybody, I could sure use some help on this one. when I turn this tv on the power supply turns on, PFC puts out roughly 400 volts on the two main caps, cp806 and cp807. I sampled the voltage at the led header connector, when the power first came on I got a little over 300 volts on both sets of gray and black wires. Im assuming two circuits and the led array would be split in half, top half and bottom half four equal led strips each circuit. that would explain the voltages being the same for both circuits... Before I pull the lcd panel and inspect the leds and wiring I would like to know what the voltages should be?
After the power supply warmed up a little the voltages both dropped to around 246volts. I tested from chassis ground and the gray wires and its the same from the gray wires to the black wires both sets are the same.



Power Supply #BN44-00776A

[budm]

Re: Samsung UN65J6200AFXZA No backlight

There are 4 wires on the LED connector, correct?
Since the LED connector is labeled to tell you what which pin is for so You need to keep the black probe of the meter on the chassis, Red probe on D1 + (D1 PLUS) then turn the TV on and watch to meter to see how high the Voltage jumps up to, then wait 10 seconds to see how low it goes down to, then turn the TV OFF then repeat the same test on D1 -, D2 +, D2 -. Notes: tests are done with all connectors in place.
According to the Voltage chart as printed on the board, the LED power supply spec is 220V 400mA, based on your report of over 300V reading it means the power supply is seeing open circuit (no load).
https://www.shopjimmy.com/samsung-bn...-led-board.htm

[high-tech]

Re: Samsung UN65J6200AFXZA No backlight

Ok, I tested the 4 wires D1+ and D2+. With the TV turned on the both had 330 volts, red probe on the D1+ and D2+
and black probe on chassis ground. So looking like I'm going to take the panel out and have a look at the LEDs...

[budm]

Re: Samsung UN65J6200AFXZA No backlight

How about D1 - and D2 -? Those are LED strings Cathode returns. So far the LED power supplies are not seeing the loads.

[high-tech]

Re: Samsung UN65J6200AFXZA No backlight

I Get nothing back on D1- and D2- the red probe on D1- and black probe on chassis ground and the same for D2- both zero volts

[high-tech]

Re: Samsung UN65J6200AFXZA No backlight

Its like the harness going into the tv isn't making it all the wat to the led array

[budm]

Re: Samsung UN65J6200AFXZA No backlight

It can be as simple as bad connectors on the LED strips.
https://www.shopjimmy.com/catalogsea...sung+UN65J6200

[sputnikoff]

Re: Samsung UN65J6200AFXZA No backlight

I replaced the two diodes d9001c & d9002c with ones from scrap board diode sf28g and replaced all lamps unit works fine.