Samsung UN32J400DAFXZA

[jeffer76]

I am working on a Samsung UN32J400DAFXZA that is not lighting the backlights. Video and sound are good.
On this model the led driver and the Main Board are combined into one board. I believe the Main is not producing proper voltage to the backlights, as I have taken the screen appart and drove the leds with a backlight tester. All the leds lit and drive at the same voltage. (13.5v)
I have replaced the Main 3 times, as the first 2 were defective, from Shopjmmy. The 3rd one is giving the same voltages as the original board.
The question is: What voltage should I be seeing at the backlights on the manin board? Am I wrong to assume there should be approx. 27v?

[jeffer76]

Re: Samsung UN32J400DAFXZA

I have measured the led voltages using the chassis ground as:
Pin4: 14.3v
Pin3: 3.4v
Pin2: 3.4v
Pin1: 3.9v
Also measured accross pin1 to pin 4: 9.8v
LEDs are in series. Top pin (pin4) of the led connector is the positive connection. Pins 3 and 2 are connectred and the bottom pin (pin1) is the negative side.

[budm]

Re: Samsung UN32J400DAFXZA

It sounds like the boost converter circuit is not being turned or working, the 14V is the input Voltage to he boost converter circuit.

[jeffer76]

Re: Samsung UN32J400DAFXZA

Looks lika another bad Main Board right?
Im surprised because Shopjimmy is usually pretty good about sending out good boards. This is the 3rd board. As stated earlier the first 2 didnt work at all.

[jeffer76]

Re: Samsung UN32J400DAFXZA

FIXED UPDATE: Found the power adaptor that the customer had brought in with the tv was the wrong adaptor for this tv. Rated for 14v, but this tv requires 19 volts. Switched to a 19v adaptor and everything operates normally.

[budm]

Re: Samsung UN32J400DAFXZA

Well, that will do it with the wrong input Voltage.