Samsung UN50EH5300FXZA No Picture

[SHADOW3277]

Picked this up cheap and trying to get it fixed. It turns on and there is no picture but I can see the menu with a flashlight.

Voltages on power supply at CNM803
pin 1 12.56v pin 2 3.44v
pin 3 12.56v pin 4 12.56v
pin 5 12.56v pin 6 3v
pin 7 12.56v pin 8 0v
pin 9 0v pin 10 0v
pin 11 5.35v pin 12 5.35v
pin 13 5.35v pin 14 3.44v

There are 2 test point for LED,s that I get 0 volts. I also get 0 volts across the connector pins LU802

There are 3 regulators on the Mainboard. All are labeled LD1117AG

I get voltages on them as follows:

0 3.3 5.1
0 1.7 5.1
.2 1.5 3.3

I have unplugged the mainboard from the PS to see if that would trigger the backlights as I've done before on other Samsung models and there was no change. I also unplugged the TCON and there was no change. Any help on how to proceed next is appreciated.

[thoma]

Re: Samsung UN50EH5300FXZA No Picture

ftp://helpedia.com/pub/temp/datashee...itors/Samsung/

ftp://helpedia.com/pub/temp/datashee...t_track_guide_[SM].pdf

[budm]

Re: Samsung UN50EH5300FXZA No Picture

At this point you are having the problem with the power supply-LED driver board becuase the backlights should be on and sttay on when the cable between the power supply and the main board is disconnected.
BTW, next time please put the pin names after the pin number so it will be easier for us to know right away as to what signals or Voltages are missing.
So more likely to be bad LEDs problem, but we need to check the DCV on the LED connector first. The LED connector has pin names for the pin so take the reading of those pins.
Samsung BN44-00668A Power Supply / LED Board
http://www.shopjimmy.com/samsung-bn4...ed-board-1.htm

The LEDs are connected in series so if one goes open circuit or high resistance then you will not have backlights.
Pictures provided by shopjimmy.

[thoma]

Re: Samsung UN50EH5300FXZA No Picture

What about BLU on_off Backlight on off

and Power on_off

[johnboy1313]

Re: Samsung UN50EH5300FXZA No Picture

You could have failed LEDs as well. I fixed a UN50EF5000FXZA recently that had several failed LEDs. Same fault. The previous owner had purchased a new PSU hoping that it would fix the issue with no luck.

[budm]

Re: Samsung UN50EH5300FXZA No Picture

Hi thoma:
They are OK.
Pin 14 (PS-ON) 3.44V
Pin 6 (BLU-ON) 3.00V

[SHADOW3277]

Re: Samsung UN50EH5300FXZA No Picture

At this point you are having the problem with the power supply-LED driver board becuase the backlights should be on and sttay on when the cable between the power supply and the main board is disconnected.
BTW, next time please put the pin names after the pin number so it will be easier for us to know right away as to what signals or Voltages are missing.
So more likely to be bad LEDs problem, but we need to check the DCV on the LED connector first. The LED connector has pin names for the pin so take the reading of those pins.
Samsung BN44-00668A Power Supply / LED Board
http://www.shopjimmy.com/samsung-bn4...ed-board-1.htm

The LEDs are connected in series so if one goes open circuit or high resistance then you will not have backlights.
Pictures provided by shopjimmy.

For the LED connector:
Pin 1 D+ 335v
Pin 2 D+ 335v
Pin 3 S1- 1v
Pin 4 S2+ 1v
Pin 5 NC 1v
Pin 6 S2- 7v
Pin 7 S3+ 7v
Pin 8 D- 7v
Pin 9 D- 7v

[budm]

Re: Samsung UN50EH5300FXZA No Picture

The boosted VLED (335VDC) is OK, you have open circuit or open LED in the LED string.
Pictures provided by shopjimmy.

http://www.shopjimmy.com/samsung-de5...s-8-strips.htm

[SHADOW3277]

Re: Samsung UN50EH5300FXZA No Picture

The boosted VLED (335VDC) is OK, you have open circuit or open LED in the LED string.
Pictures provided by shopjimmy.

http://www.shopjimmy.com/samsung-de5...s-8-strips.htm

Those strips at SJ don't match my panel# but I do see some on ebay for sale I'll give a shot.

Thanks for the help budm and everyone.

[budm]

Re: Samsung UN50EH5300FXZA No Picture

It can be due to the bad connection at the board terminals so you may want to check them out first.

[thoma]

Re: Samsung UN50EH5300FXZA No Picture

@budm would it be possible to post

the DCV on the LED connector when the LCD-TV is repaired?!

This would help for orientation a lot of technicians!It should be no problem

to measure after repair and post it!!!

regards thoma!!

[budm]

Re: Samsung UN50EH5300FXZA No Picture

There is chart printed on the board for the Output Voltage of the LED connector, it shows as 229VDC 470mA (it may not be true for this TV since same blank board may be stuffed with difference parts for difference Voltage requirement), that should be the running Voltage with loads, but we will find out when the OP fixed the problem and take the reading after the repair is done.

[thoma]

Re: Samsung UN50EH5300FXZA No Picture

Thank you budm!
I can see if I read your threads that you are absolute profi!
You know what you are talking about!!
Very good!!!!
regards Thoma!

[budm]

Re: Samsung UN50EH5300FXZA No Picture

Thank you budm!
I can see if I read your threads that you are absolute profi!
You know what you are talking about!!
Very good!!!!
regards Thoma!

Thanks for all those links to the service manual, especially the one for the SAMSUNGs.

[thoma]

Re: Samsung UN50EH5300FXZA No Picture

No Problem!Budm!

ftp://helpedia.com/pub/temp/datasheets/monitors/

more schematics from other producers!

regards thoma!