Samsung UN46D7000 46'' LED; No Power

[beedoola]

I just bought the mentioned tv in hopes to repair it- owner said it worked sometimes but often not. When I got it home, I first opened it up thinking there may be an obvious bad cap inside. There was not indication, from visual inspection, that there was any bulging. So it worked.

Then just now when I tried to power it, the front lower red power indicator flashes 6 times. If I unplug the power cord, I hear about 4 or 5 clicks coming from the rear left of the TV - where the PS is located. I also came back a few minutes later - after leaving the power cable plugged in to find the TV on with audio but no video...

I tested the 3 fuses with my Multimeter. The larger one, near the power cable input is at 57v on both sides, the other two smaller fuses are both at 12v - one near the heatseak on the right being at 12.2v.

Here is a pic of the PS board. All I have in terms of a camera is my iphone..

[randtek]

Re: Samsung UN46D7000 46'' LED; No Power

The first thing I do on these is to try to confirm proper power board operation. You can do this as follows:
1. Unplug power to TV
2. Disconnect one end of the cable that runs from the power board to the main board.
3. Plug the power cord of the TV back into the wall.
4. Check for light at holes in the aluminium rear of the panel, such as the one right below the power board in your photo.

If you see light, and it stays lit, your power board is probably good. In this case, I am betting you will not see any light. That would indicate that you have a power supply or backlight issue.

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

I unplugged the connector to the main board. I'm not sure if I'm looking at the right areas but I did not see any light. I head one click from the relay when I plugged the power cord in and one click when I removed it.

Also do you know what the blinking code refers to? The 5 or 6 flashes from the indicator LED.

Also, again. I'm not sure if this matters but I noticed that when the tv is plugged in and my finger runs over the rear panel controls; power, channel and source buttons, the LED indicator flashes rapidly. I don't even have to push the buttons. Just touching them causes the LED to flash rapidly.

[tom66]

Re: Samsung UN46D7000 46'' LED; No Power

On a Samsung, the blinks mean nothing -- ordinary power up blinking indicating they are warming up.

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

On a Samsung, the blinks mean nothing -- ordinary power up blinking indicating they are warming up.

you mean the rapid LED blinking or the 5 or 6 pulses I mentioned?

[tom66]

Re: Samsung UN46D7000 46'' LED; No Power

Yes. The LE40A656 I fixed in the lounge does 4 or 5 blinks when you press the button.

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

The first thing I do on these is to try to confirm proper power board operation. You can do this as follows:
1. Unplug power to TV
2. Disconnect one end of the cable that runs from the power board to the main board.
3. Plug the power cord of the TV back into the wall.
4. Check for light at holes in the aluminium rear of the panel, such as the one right below the power board in your photo.

If you see light, and it stays lit, your power board is probably good. In this case, I am betting you will not see any light. That would indicate that you have a power supply or backlight issue.

so you're correct; I didn't see any light.

I mentioned in my OP that the TV worked for a bit and then stopped. It also came back on later - just the audio, before shutting off.

Are there any other tests I can do to confirm for sure that it is the PS board?

[randtek]

Re: Samsung UN46D7000 46'' LED; No Power

You should check the power supplies with the main board cable still disconnected, so the power board is being forced on, and see if all of the voltages come up. Most of them will be labeled on the legend for the power supply to main board connector. I am not at work, so I cannot tell you what the correct voltages are for the LED drive connectors. Maybe someone else can give you those. Unfortunately, there aren't standard values for them, they are panel specific.

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

You should check the power supplies with the main board cable still disconnected, so the power board is being forced on, and see if all of the voltages come up. Most of them will be labeled on the legend for the power supply to main board connector. I am not at work, so I cannot tell you what the correct voltages are for the LED drive connectors. Maybe someone else can give you those. Unfortunately, there aren't standard values for them, they are panel specific.

I see the legend next to the main board connector - which disengages the pins but they don't have voltages next to them, just descriptions; end, etc.

There is another legend on the bottom right that has a list of three points with voltages...

Also; Anyone with access to the service manual might be able to upload it? It would be much appreciated. Thanks.

[budm]

Re: Samsung UN46D7000 46'' LED; No Power

You decide not to fix down to component level, the board is around $80 when he has in stock.
http://www.shopjimmy.com/samsung-bn4...upply-unit.htm

http://www.rivervalleyelectronics.ne...er-supply.aspx

[randtek]

Re: Samsung UN46D7000 46'' LED; No Power

I see the legend next to the main board connector - which disengages the pins but they don't have voltages next to them, just descriptions; end, etc.

There is another legend on the bottom right that has a list of three points with voltages...

Also; Anyone with access to the service manual might be able to upload it? It would be much appreciated. Thanks.

Look on the power board next to the connector. I know the legend is there. It is visible on your photo.

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

Look on the power board next to the connector. I know the legend is there. It is visible on your photo.

yeah, sorry. I didn't realize the lower legend with the voltage spots corresponded to the Main Board connector.

Below is a picture of the voltages legend - mine are the voltages on the left side.

A5 and B5 are 5.3 exactly as is specified on the board.

B13V and Vamp - there are two pins for each, read 14.17v, the board says 12.8v.

[budm]

Re: Samsung UN46D7000 46'' LED; No Power

How about the LED output drive voltage of 176V?
Also, are you getting any DC voltages on these 4 caps for the LED power supply with the POWER to LED connected and not connected?

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

Voltages on the 4 electro caps in the pic vary from around 73v-91v, they all are like that and jump around when measuring it. Don't think it's my meter as I get stable readings elsewhere.

On the LED output. On the CNL802b, I get 107v on pins 1,2, 11 and 12.

I get no voltage on any of the other pins on the other port. The port on the right is the 802b. These were all taken with the connectors off. Putting them on, I will don't get 176v any where on the led output connections

Edit*** with the led connectors on, those caps that had the varied voltages now read a stable 108v, all of them

[budm]

Re: Samsung UN46D7000 46'' LED; No Power

OK, on those two connectors, there are chart showing the pins of those connectors. Can I see the good clear pictures of them?
We also need to check the resistance of the LED female connectors between the chassis and each one of those pins on the connectors to make sure there is no short circuit to ground.

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

I saw you post before you edited it. I rechecked those 4 DC electro caps again - with the LED connectors off and they give off a stable 107v DC. Weird that they varied last time I checked without the connectors on.

OK, on those two connectors, there are chart showing the pins of those connectors. Can I see the good clear pictures of them?
We also need to check the resistance of the LED female connectors between the chassis and each one of those pins on the connectors to make sure there is no short circuit to ground.

you mean resistance or continuity? And if resistance, should I do that with the power on?

[budm]

Re: Samsung UN46D7000 46'' LED; No Power

We need to probe the connectors next to make sure the wires to the LED assemblies are not shorted to ground somewhere. You can use beeper mode to do this testing.
Can I also get good clear pictures on the bottom side of the board around those connectors and the LED power supply sections. I need to see how many LED strings are used in this TV. May have 4 strings from the look of the power supply setup.
Also good clear pictures of the whole bottom side of the board.

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

I checked the male connectors as well as the female - using resistance for the latter, with no shorts. Here are the bottom pics. The first two are of the under side with the LED connectors. The other 4 are sections of the bottom. I only have an iphone as a camera so I tried to do the best I could..

[budm]

Re: Samsung UN46D7000 46'' LED; No Power

Its the female side that I worry about. Some other people here has found bad wiring that are shorted to the chassis before.
All the resistance on all the female pins and the the chassis show OL or open circuit right? It should not show any resistance what so ever.

[beedoola]

Re: Samsung UN46D7000 46'' LED; No Power

well I'm getting 32M on Pin 16 of the CNL802A female connector. Power is off.

EDIT*** I don't know if that was a fluke or if my finger was touching either the LED male connector or the positive DMM probe but I'm not getting an resistance now, just OL reading on the DMM. using a Fluke 117