Samsung LED UN46H5203 No Backlights

[sfernandes]

Hey guys,

I need some help trying to troubleshoot this set.

I have tested the LED Backlights with the Shopjimmy LED backlight tester and I could see through the back of the panel the LEDs lighting up.

Flashing a flashlight into the panel I could see the image.

I have taken voltage measurements here they are...

TV in running mode

CNM803 CONNECTOR ON PSU

Pin 1 - 13v

Pin 2 - 13v

Pin 3 - 13v

Pin 4 - 13v

Pin 5 - 0v

Pin 6 - 3.297v

Pin 7 - 1.578v

Pin 8 - 3.328v

5303 CONNECTOR ON PSU

Pin 1 - 310v

Pin 2 - 308v

Pin 3 - 260v

Pin 4 - 262v

Pin 5 - 0v

Pin 6 - 235v

Pin 7 - 233v

Pin 8 - 0v

Pin 9 - 0v

TV IN STANDBY

CMN803 CONNECTOR ON PSU

Pin 1 - 11.95v

Pin 2 - 11.95v

Pin 3 - 11.95v

Pin 4 - 11.95v

Pin 5 - 0v

Pin 6 - 0v

Pin 7 - 0v

Pin 8 - 0v

Pin 9 - 0v

5303 CONNECTOR ON PSU

Pin 1 - 208v

Pin 2 - 208v

Pin 3 - 159v

Pin 4 - 159v

Pin 5 - 0v

Pin 6 - 134v

Pin 7 - 134v

Pin 8 - 0v

Pin 9 - 0v

I have attached pictures showing the PSU and the Main and also close-ups of the pin legends. I also have the service manual for this set, but it's not really informative. Another thing I find odd that I should mention is that the standby voltage on this set is supposed to be 8v according to what's printed on the PSU meanwhile on standby it's running 11.95v, not sure if that's an issue, but it's worth noting.

[budm]

Re: Samsung LED UN46H5203 No Backlights

The connector has pin label for each pin so you should put the name of each pin on the connectors that you report so we can easily see what each pin is for.
Also recheck the way you count the pin and the pin name as listed in the chart, I.E, the CNM803 connector has odd and even column pins, the odd pins can be access from the top side of the board the even number pins has to access from the wire entrance side of the connector.
Your report for
CNM803 CONNECTOR ON PSU

Pin 1 - 13v

Pin 2 - 13v

Pin 3 - 13v

Pin 4 - 13v

Pin 5 - 0v

Pin 6 - 3.297v

Pin 7 - 1.578v

Pin 8 - 3.328v

Look at your pin number and the report, you will see that they do not match the chart (the connector has 10 pins), as you can see fro example the pin 8 is GND so how can you have 3.328V, that is why you need to put down the name then you can easily see the errors you made.


Please redo you measurement again.

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

The connector has pin label for each pin so you should put the name of each pin on the connectors that you report so we can easily see what each pin is for.
Also recheck the way you count the pin and the pin name as listed in the chart, I.E, the CNM803 connector has odd and even column pins, the odd pins can be access from the top side of the board the even number pins has to access from the wire entrance side of the connector.
Your report for
CNM803 CONNECTOR ON PSU

Pin 1 - 13v

Pin 2 - 13v

Pin 3 - 13v

Pin 4 - 13v

Pin 5 - 0v

Pin 6 - 3.297v

Pin 7 - 1.578v

Pin 8 - 3.328v

Look at your pin number and the report, you will see that they do not match the chart (the connector has 10 pins), as you can see fro example the pin 8 is GND so how can you have 3.328V, that is why you need to put down the name then you can easily see the errors you made.


Please redo you measurement again.

My bad, I'm sorry for my mistake here are new measurements.

ON STATE

CNM803 on PSU from Main

Pin 1 A13v - 12.94v

Pin 2 OD_UD - 3.297v

Pin 3 A13v - 12.94v

Pin 4 BLU_PWM - 1.574v

Pin 5 A13v - 12.94v

Pin 6 PWR_On/Off - 3.328v

Pin 7 A13v - 12.94v

Pin 8 GND - 0v

Pin 9 GND - 0v

Pin 10 GND - 0v


STANDBY STATE

CNM803 on PSU from Main

Pin 1 A13v - 11.90v

Pin 2 OD_UD - 0v

Pin 3 A13v - 11.91v

Pin 4 BLU_PWM - 0v

Pin 5 A13v - 11.93v

Pin 6 PWR_On/Off - 0.126v

Pin 7 A13v - 11.94v

Pin 8 GND - 0v

Pin 9 GND - 0v

Pin 10 GND - 0v

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

CNL802 CONNECTOR ON PSU TO LED's

ON STATE

Pin 1 D1+ - 310v

Pin 2 D1+ - 308v

Pin 3 S1- - 260v

Pin 4 S2+ - 262v

Pin 5 NC - 0v

Pin 6 S2- - 235v

Pin 7 S3+ - 233v

Pin 8 D1- - 0v

Pin 9 D1- - 0v


STANDBY STATE

Pin 1 D1+ - 208v

Pin 2 D1+ - 208v

Pin 3 S1- - 159v

Pin 4 S2+ - 159v

Pin 5 NC - 0v

Pin 6 S2- - 134v

Pin 7 S3+ - 134v

Pin 8 D1- - 0v

Pin 9 D1- - 0v

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

CNL802 CONNECTOR ON PSU TO LED's TESTED WITH CABLE DISCONNECTED WITH POWER ON

Pin 1 D1+ - 305.2v

Pin 2 D1+ - 305.0v

Pin 3 S1- - 0v

Pin 4 S2+ - 0v

Pin 5 NC - 0v

Pin 6 S2- - 0v

Pin 7 S3+ - 0v

Pin 8 D1- - 0v

Pin 9 D1- - 0v


CNL802 CONNECTOR ON PSU TO LED's TESTED WITH CABLE DISCONNECTED WITH TV ON STANDBY

Pin 1 D1+ - 207.5v

Pin 2 D1+ - 207.7

Pin 3 S1- - 0v

Pin 4 S2+ - 0v

Pin 5 NC - 0v

Pin 6 S2- - 0v

Pin 7 S3+ - 0v

Pin 8 D1- - 0v

Pin 9 D1- - 0v

Tried running the TV without the cable that connects the main to the PSU to see if I get backlights, but I didn't get anything (Not sure if this unit has pull up resistors in the power supply)

Shopjimmy sells a new IC1304 for this set

https://www.shopjimmy.com/samsung-bn...eprom-only.htm

Not sure if that would fix my problem.

[nomoresonys]

Re: Samsung LED UN46H5203 No Backlights

Seems like "Pin 4 BLU_PWM - 1.574v" is too low, thinking that's the backlight on signal coming from the mainboard.

[nomoresonys]

Re: Samsung LED UN46H5203 No Backlights

Could try unplug the wifi module and see if tv starts up.

[neilc6]

Re: Samsung LED UN46H5203 No Backlights

You most likely have bad backlights. You can report the voltages read by the led tester probing from the back connector or open up the panel to observe each strip powered from the tester. EH and H series, the LEDs will burn out until there are only a few working or there is an open in the string or there is damage to the PS..

[R_J]

Re: Samsung LED UN46H5203 No Backlights

I agree, backlight led problems, likely one or two are shorted causing abnormal current and shutting down the led circuit.

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

Could try unplug the wifi module and see if tv starts up.

Tried that and same thing.

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

You most likely have bad backlights. You can report the voltages read by the led tester probing from the back connector or open up the panel to observe each strip powered from the tester. EH and H series, the LEDs will burn out until there are only a few working or there is an open in the string or there is damage to the PS..

The voltages on the LED tester say...

Pin 1 & 2 - 55.1v

Pin 4 - 29.9v

Pin 7 - 0v

Pin 8 & 9 - 85.8v

What do you figure from those numbers?

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

Seems like "Pin 4 BLU_PWM - 1.574v" is too low, thinking that's the backlight on signal coming from the mainboard.

I'm getting mixed opinions, I would prefer not to have to risk taking out the panel if I don't have to.

Could anyone be more sure what's happening?

budm any ideas I haven't heard your opinion yet?

[R_J]

Re: Samsung LED UN46H5203 No Backlights

The voltages on the LED tester say...

Pin 1 & 2 - 55.1v

Pin 4 - 29.9v

Pin 7 - 0v

Pin 8 & 9 - 85.8v

What do you figure from those numbers?

The pin numbers are wrong, Pins 1&2 are the same connection, pin 5 is not used, pins 8&9 are connected together.
Disconnect the plug and check the 3 strings:
Between pins 2&3, 4&6, 7&8

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

The pin numbers are wrong, Pins 1&2 are the same connection, pin 5 is not used, pins 8&9 are connected together.
Disconnect the plug and check the 3 strings:
Between pins 2&3, 4&6, 7&8

Ok here are the correct pin readouts...

Pins 2 & 3 - 55.1v ( Panel lights up)

Pins 4 & 6 - 29.9v (Panel lights up)

Pins 7 & 8 - 313v (panel doesn't light up)

What does this mean?

[budm]

Re: Samsung LED UN46H5203 No Backlights

Ok here are the correct pin readouts...

Pins 2 & 3 - 55.1v ( Panel lights up)

Pins 4 & 6 - 29.9v (Panel lights up)

Pins 7 & 8 - 313v (panel doesn't light up)

What does this mean?

You have open circuit on the LED string connected to pin 7 (Anode of #3 LED string) and 8 (Cathode of the #3 LED string which is the Cathide return of the series connected LED strings).

[R_J]

Re: Samsung LED UN46H5203 No Backlights

Ok here are the correct pin readouts...

Pins 2 & 3 - 55.1v ( Panel lights up)

Pins 4 & 6 - 29.9v (Panel lights up)

Pins 7 & 8 - 313v (panel doesn't light up)

What does this mean?

It looks like the string between 7&8 is open.

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

Great so I guess opening the panel it is sigh lol. I have many LEDs from tvs laying around could I not just replace the burnt out ones, if so are all LEDs the same?

[budm]

Re: Samsung LED UN46H5203 No Backlights

They are not all the same, you have to match the footprint and polarity, Voltage and current rating, etc.
It is better to replace the whole set of the LED strips.

[sfernandes]

Re: Samsung LED UN46H5203 No Backlights

They are not all the same, you have to match the footprint and polarity, Voltage and current rating, etc.
It is better to replace the whole set of the LED strips.

This set belongs to a friend that says he doesn't want to spend money on it really and asked me if there is a way to jumper the LED to the next led, then turn down the backlight so he could get a bit more out of it. Is that possible?

[budm]

Re: Samsung LED UN46H5203 No Backlights

You may be able to bypass one to two 3V LEDs, I would not do more than that. The problem is that some LEDs already went bad so you can expect more to go bad later also.