Samsung LNS4051DX

[Rmasters3]

Intermittently stops and goes to black screen, shutting down. I've replaced 6-7 caps, the 1000uf's that typically fail and a couple others. Hear a click when power button is pushed. Occasionally the set starts and will run long term, most of the time nothing beside the click, or will run 20-30 minutes and shut down.

I'm still thinking power supply, but don't know where else to go.

[jeffegg2]

Re: Samsung LNS4051DX

https://www.badcaps.net/forum/showthread.php?t=39740

[Rmasters3]

Re: Samsung LNS4051DX

Not sure how this link pertains to my question.

[budm]

Re: Samsung LNS4051DX

Not sure how this link pertains to my question.

Well, we do not have the TV, we do not have crystal ball, or the boards in front of us to see what YOUR VERSION of your TV has, how all the boards are connected together, so at least provide us good clear pictures so we can give you the test points to test.
Does that make sense to you now?

BTW: As you can see below, there are more one version of the boards used in your model.
http://www.shopjimmy.com/catalogsear...sung+LNS4051DX

[Rmasters3]

Re: Samsung LNS4051DX

The power supply board is a BN44-00134A. I have replaced the electrolytic caps in the upper right corner, most of these being 1000uf 10V, replaced with 1000uf 35V.

[budm]

Re: Samsung LNS4051DX

OK, please take the DC Voltage readings on the white connector that goes to the main board and report the reading of each pin with its name next to it.
http://assets.shopjimmy.com/media/ca...bn4400134a.jpg
The readings on each pin when TV is plugged in and when the power switch is activated.

[Rmasters3]

Re: Samsung LNS4051DX

I pushed power button at front with PSB disconnected at 16 pin connector to Main board. Only voltage I was able to get was lowest pin STB spec-ed at 6.5V and I got
7.58 VDC.

Remaining pins 0. Some pins were GND's others 5.4V up to topmost at 13V, but none produced any voltages.

[budm]

Re: Samsung LNS4051DX

You have to have all the cables connected so we can see if the STBY Voltage is OK, and if the command signals are OK.
When the main board is not connected, the power supply will not get the command signals from the main board to turn on the main power supply.
You also need to verify that the batteries for your meter are OK, low batteries will make the meter show higher readings.

[Rmasters3]

Re: Samsung LNS4051DX

Will check the batteries in the meter. How do I go about checking the voltage with the connector attached--do I go in through the top with a sharp probe, etc?

[Rmasters3]

Re: Samsung LNS4051DX

With white connectors in place--I get the STB voltage only about 6.58V, no voltage at any of the other pins.

[budm]

Re: Samsung LNS4051DX

So the STBY Voltage is OK, it is labeled as 6.5VDC and you are getting 6.58VDC.
Since there is no other Voltage readings, especially on the P-ON/OFF pin, that means the main board is not sending the power on command to turn on the main power supply circuits, the P-ON/OFF should be >2.5VDC when power switch is activated.
So you have problem some where on the main board.

[Rmasters3]

Re: Samsung LNS4051DX

Thanks for the reply. Right now the set is working, again. I'm letting is run for a while, turn on/off to see if I can replicate the problem. (It just shut down again. FWIW: I do have audio.)

Assuming a main board problem is there anything in particular on these main boards (BN-97-00810A) I should look at?

[budm]

Re: Samsung LNS4051DX

"(It just shut down again. FWIW: I do have audio.)"
OK you still have audio, that means you should check and see if the P-ON/OFF signal and all other Voltages are present on the connector.

[Rmasters3]

Re: Samsung LNS4051DX

All the other voltages checked out on the connector, when I have audio.

I didn't know if you meant the P-On/OFF signal was on that connector or elsewhere, I did see something similar on a smaller connector above the 16 pin--there was 5.15V on that spot. on the board--sorry.

[budm]

Re: Samsung LNS4051DX

P- ON/OFF pin on the power supply board.

[Rmasters3]

Re: Samsung LNS4051DX

3.72V on the P- ON/OFF, TV working with audio & video. .02V when set is on but there's no video or audio.

[budm]

Re: Samsung LNS4051DX

3.72V on the P- ON/OFF, TV working with audio & video. .02V when set is on but there's no video or audio.

OK, I am confused, 3.72V when TV is working and you do have Video and Audio.
0.02V when TV is not working (even when power switch is activated) and you do not have audio or Video, then that means the main board is not sending the POWER ON/OFF to turn on the main power supply.

[Rmasters3]

Re: Samsung LNS4051DX

P- ON/OFF is 3.72 when set is working, .02 when set does not have video or audio--correct

[budm]

Re: Samsung LNS4051DX

P- ON/OFF is 3.72 when set is working, .02 when set does not have video or audio--correct

So main board is bad and not sending the signal.

[Rmasters3]

Re: Samsung LNS4051DX

Thanks for the help--I'll find a replacement main board.