samsung un46eh5000fxzc no backlight HELP

[rmacleod96]

My 46 incher just up and quit .
i need a little help deciding whether its the leds open cct or the
power supply board . I have 210 volts at D1+ , 0 volts at D1-
the 3 led strips on this tv seem to be in series, is this correct ?
Can i test the led strips somehow or do i have to test them
individually TIA

[budm]

Re: samsung un46eh5000fxzc no backlight HELP

You have open circuit in the LED strings, the D1+ is the Anode of the first LED string which should be connected to the B+ of the LED power supply, the D1- is the Cathode side of the first LED string which should be connected to the Anode of the second LED string, since you are getting 0V on the D1-, that means you have open circuit in the first string.
Are you getting 210V with (loaded) or without (not loaded) the LED connector in place? If you do that also indicates open circuit.
You can test each LED or if you know many LEDs there are in each string then you can calculate the power supply Voltage and the value of the current limiter resistor.

[rmacleod96]

Re: samsung un46eh5000fxzc no backlight HELP

yes i get over 200 volts at D1+ with the connector plugged in or not
and the powersupply shows no sign of burn marks , but the arangement of the leds has me a little confused, the connector is designated
D1+. S1-. S2+. nc. S2-. S3+. D1-. and the way the copper traces
are on the bottom of the board it looks like all three led circuits are in series
Right ?

[budm]

Re: samsung un46eh5000fxzc no backlight HELP

We need Pictures of the whole back side of the TV, and the power supply board both top and bottom side, closed up pictures around the connector.
S?, are the sensing pins.
Power supply board P/N BN44-?????
'yes i get over 200 volts at D1+' at this point, you have open circuit in the LED strings some where.

[rmacleod96]

Re: samsung un46eh5000fxzc no backlight HELP

here is a closeup of the connector i'll try to get a few better ones tonight
the power supply is BN44-00667A

[budm]

Re: samsung un46eh5000fxzc no backlight HELP

More likely to be the same as this one, LED failures are very common in LED backlights TV.
https://www.badcaps.net/forum/showth...ht=BN44-00667A

[rmacleod96]

Re: samsung un46eh5000fxzc no backlight HELP

well i took the plunge and cracked the tv wide open
to get to the leds .this is what i found
there are four strings of leds.
each string is made of two smaller strings
the left section has 6 leds
the right section has 5 leds
the power supply has 3 pairs of wires going to the leds
i guess that the power supply is used in other models of tv
the top two led strips is wired in series to one pair of wires
the next two led strips each are fed by one pair of wires
all the led strips ore wired in series at the connector on the power supply
thats 44 leds all in series
i tested the strings using 2 9v batteries in series
i tested the right section by connecting at the junction of the strips
i tested the left section by connecting at the connector and shorting
the strips at the junction
the result ..
8 leds with little or no light and one open strip ( top left )
this tv is done !

[rmacleod96]

Re: samsung un46eh5000fxzc no backlight HELP

pics
thanks for the help

[budm]

Re: samsung un46eh5000fxzc no backlight HELP

You can try getting a new set of the LED strips.

[Ndoty22]

That's not done, here is the same strip

[Ndoty22]

Cnl802 backlights