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Samsung un65au8000f xzc"No power -No Start

Samsung un65au8000f" No power -No Start with a Bn4401111A power board. No power indicator light. Upon powering and disconnecting cable main board, no back lights. There is "0" voltage on any pins on connecting cable to main board, The fuse is good. Power board is bad. Might someone suggest components to check which might causse "0" output from power board? No apparent burns. No apparent capacitor bulging.

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My deepest apologies. the abreviated message below still holds true, BUT, the values(voltages) I posted were totally FALSE. Please forgive me oldturkey03. Here is an update.

1/ Grd,

3/ 12.86vdc

5/ 12.86vdc

7/ 12.86vdc

9/ 12.86vdc

11/ Grd

2/ Ana Dim .92vdc

4/ Pwm2 Hi .00vdc

6/ Pwm1 low 3.29vdc

8/ Power on 4.51vdc

10/ Grd

12/ Grd

"Samsung un65au8000f" No power -No Start with a Bn4401111A power board. No power indicator light. Upon powering and disconnecting cable main board, no back lights."

Again my apologies.

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Hope this helps someone. It appears as though my power board was ok. My power button was inoperable. My back lights were partialy burnt out. Combined these left me with the thought that the power board was the culpert. I wish to thank oldturkey03 for for his input and thoughts. Much appreciated.

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@john65845 there is not a single component that we could identify as a prime suspect. There are just too many variables. What makes this even more difficult is the fact that schematics are not being published for theses boards.

I would try and work my way up from the fuses and check the components. Voltage regulators, Mosfet and diodes are on top of that list.

Post some really good pictures of your power board with your Question. Who knows, maybe we'll find something?

Adding images to an existing question - iFixit Repair Guide

Update (07/19/23)

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Be cautioned! You are going to have to check this with the power plugged in etc. So, do not touch anything with your bare hands/fingers etc. It will bite!

These are almost all AC power checks. Set your meter accordingly (above 120VAC).

You said the fuse was okay, but did not tell us how you checked it. If you checked it for continuity, you will have to check it for power. Red on one of the leads and lack to the line on the AC connector. Then the other lead. You will need to see that it has full household power.

Next check the rectifier. Outside leads are DC inside leads are AC. Red on one and Black probe on the other lead. What do you get?

There is one area that looks odd, I asked for a close up of that.

Check your capacitors from the side. Do they looked domed (tops bulging)? It's hard to see on your image.

Now a big question. The underside of your power boards looks drenched. Did this have water damage or what kind of liquid is this?

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My deepest apologies. the abreviated message below still holds true, BUT, the values(voltages) I posted were totally FALSE. Please forgive me oldturkey03. Here is an update.

1/ Grd,

3/ 12.86vdc

5/ 12.86vdc

7/ 12.86vdc

9/ 12.86vdc

11/ Grd

2/ Ana Dim .92vdc

4/ Pwm2 Hi .00vdc

6/ Pwm1 low 3.29vdc

8/ Power on 4.51vdc

10/ Grd

12/ Grd

"Samsung un65au8000f" No power -No Start with a Bn4401111A power board. No power indicator light. Upon powering and disconnecting cable main board, no back lights."

Again my apologies.

- de

@john65845 no problem at all. So it looks like your power board is not in bad shape at all. We just need to figure now how to get those voltages to the rest of the system. Let me do a bit of researching your system.

- de

Should the Voltage being supplied by way of CNL801, (or the Led output connector) be AC or DC?

I wish to thank you for taking the time trying to help me out.

- de

""Next check the rectifier. Outside leads are AC inside leads are DC. Red on one and Black probe on the other lead. What do you get?"" AC terminals varies, like a cap is discharging. DC terminals are steady, with output at 120 AC volts. Wow you have hit the nail on the squarely on the head. Now why??

I am having trouble getting my answer to your question, so here is an edit. Hope this works.

While the meter is on AC reading the outside terminals read 22vac down to 0vac, the inside two terminals read 120vac, While the meteris on DC reading the outside terminals read 165vdc, the inside two terminals read 0.00vdc

Please excuse me if I am not posting these statements correctly.

- de

@john65845 what voltages did you get?

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