Samsung UN46EH5000F no backlight

[m4a2t0t]

Trying to figure out why the backlight went out. No visible bad caps or burning on power board. Shining light on panel I can see the menu.

Read this post
https://www.badcaps.net/forum/showthread.php?t=50471
Everything looks the same but I will get pics if you want.

Unplugged the cable from power board to main board.

Voltage across main cap on power board - .115 V
D1+ to chassis gnd = .001V - sometimes I see it jump to 1.7 and then back down.
I can hear a light whining coming from the board.

Where should I start?

[ReeceyBurger123]

Re: Samsung UN46EH5000F no backlight

Check output voltage going to backlights.

[m4a2t0t]

Re: Samsung UN46EH5000F no backlight

All pins on CNL802 connector are below 1.0V, most are .3V to .6V

[budm]

Re: Samsung UN46EH5000F no backlight

Please upload pictures of YOUR boards, also what is the P/N of your POWER SUPPLY /LED driver board BN44-?????

[m4a2t0t]

Re: Samsung UN46EH5000F no backlight

I'll upload some in a min.

BN44-00667A

[m4a2t0t]

Re: Samsung UN46EH5000F no backlight

any suggestions.

Is there a way to test the backlight and make sure it didn't cause the problems with the power board.

[CapLeaker]

Re: Samsung UN46EH5000F no backlight

Turn the TV on and check the BLon pin on the PSU (bottom left corner).

[thoma]

Re: Samsung UN46EH5000F no backlight

[m4a2t0t]

Re: Samsung UN46EH5000F no backlight

I assumed the top left pin was pin 1.

1-12.8
2-1.04
3-12.8
4-12.8
5-12.8
6-4.8
7-12.8
8-10-GND
11-5.2
12-5.2
13-5.2
14-3.4

[budm]

Re: Samsung UN46EH5000F no backlight

Pin names for each pin?

[m4a2t0t]

Re: Samsung UN46EH5000F no backlight

CN803 IP SMPS to /fro MAIN BOARD
1-B13V
2-PWM_DIMM
3-B13V
4-B13V
5-Vamp 13V
6-BLU On/Off
7-Vamp 13V
8-GND
9-GND
10-GND
11-B5V
12-A5V
13-B5V
14-Power On/Off

[m4a2t0t]

Re: Samsung UN46EH5000F no backlight

Well, I am just going to order a new power board. Hopefully that is it

[budm]

Re: Samsung UN46EH5000F no backlight

You have all the correct Voltages. I doubt it is the power supply board.
https://www.badcaps.net/forum/showth...ht=BN44-00667A
https://www.badcaps.net/forum/showth...ht=BN44-00667A

[ed123]

Re: Samsung UN46EH5000F no backlight

Hi Bud,
I have the same TV and when I disconnect the main board the backlight turns on by itself.Does that mean the LED's are ok and the main boards the problem?
Ed

[dick_barton]

Re: Samsung UN46EH5000F no backlight

If the backlights come on with the mainboard disconnect then it generally indicates a problem on the mainboard.
Can you list all the voltages as in post #11

[ed123]

Re: Samsung UN46EH5000F no backlight

Thank you for the quick responce.I was following the procedure until I unpluged the main from the power board to check the voltage at the 450volt cap and it showed about 385v and i saw all the leds light up.So I'm hoping a 23$ board from eparts on ebay will do the trick.Most people with this TV are having LED backlight issues.But I can't imagine a bad LED would light up.
The other thing I failed to mention was when the main board is connected,I can turn the TV on it makes the samsung "jingle" the backlight is OFF but I can barely see the menu option.The other important thing I think is I cannot turn the tv off using the power switch.I have to pull the plug from the wall.
sounds like an unlikely defective main board doesnt it?
Ed

[budm]

Re: Samsung UN46EH5000F no backlight

"The other important thing I think is I cannot turn the tv off using the power switch.I have to pull the plug from the wall.
sounds like an unlikely defective main board doesnt it?"
Yes.

[ed123]

Re: Samsung UN46EH5000F no backlight

Thank you both for the quick responses I'll post when the board come in.
Bud,
I might have lucked out on this one.It might be interesting to note that unplugging the main from the power supply made the LED light up,is that normal?
Ed

[budm]

Re: Samsung UN46EH5000F no backlight

Thank you both for the quick responses I'll post when the board come in.
Bud,
I might have lucked out on this one.It might be interesting to note that unplugging the main from the power supply made the LED light up,is that normal?
Ed

Yes, that is normal, that is how you do the self test of the power supply and backlights.

[ed123]

Re: Samsung UN46EH5000F no backlight

Well....I got the new main board in from electro parts and nothing.The TV turns on when it's plugged in and no backlight and I cannot turn it off by the remote or the power switch.I called e-parts back and will try the power supply.But still when the main is unplugged the backlights all turn on.