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Old 05-13-2019, 09:08 AM   #1
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Default Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Got one of these skinny LED TV's with LED illumination that comes from the sides.

Had the random screen flash because of burnt-out LED strip. I was able to confirm that the rest of the electronics was working as I did the " Flashlight test" and the image was on the whole screen and I got sound too.

Fixed it with LED replacements, and worked for a few minutes, and then I got a stun-gun type of pop, yet I thought some electrolytic cap popped, but the connection to one of the LED strips was having a high-voltage leak, and sorting to the aluminum frame of the TV.

Now, I get the random flash LED light flash, but when I see the screen with the flashlight the image flashes on for 10 seconds or so on then off for 3 or 5 seconds, so makes me think some kind of short. I tested the LEDs and the whole strips turn on. I get this with the LED illumination strips connected or disconnected.

I had found the "schematics", but I guess the diagrams are no longer in service manuals, so I will do some random DC volt tests to see if the voltage is pulsing. I need to find them again. Maybe I overlooked something.


I did see a you tube a while ago on someone disabling the feedback side of the power side to the digital board to control the illumination, but I need to find that you tube on how and where it is done.


Any insight I would appreciate it..

Thanks
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Old 05-14-2019, 06:49 PM   #2
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

all I can think of is try to turn the back lights down as far as they go and see if something changes compared to running the back lights on full tilt.
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Old 05-14-2019, 11:34 PM   #3
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Thank you for your reply, yet I did try that, and it still does it. I disconnected the illumination LED power connection from the power supply and it still flashes.

And the back-lights were NOT at full-tilt either.
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Old 05-14-2019, 11:56 PM   #4
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Can we see good clear pictures of what we are dealing with, I.E. the whole backside of the TV showing all the boards, straight shot pictures of the whole power supply board, etc.?
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Old 05-15-2019, 01:48 AM   #5
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

I fear HV may have leaked where it shouldn't and ruined the main board.
Pictures would help indeed.
For now, remove the connector between the main board and the PSU and the PSU should come on by default. i.e. all its power rails should go up and be stable as soon as you plug it in. Measure the 12v and 5v outputs to see what you get. You can then take it one step further and load them with a lightbulb to see if they still maintain regulation.
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Old 05-15-2019, 11:38 PM   #6
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Budm,

I took the pictures, but need to upload them through another computer, and the family is all asleep, so tomorrow morning I will upload them.

The power supply electrolytic capacitors look good, and no blistered tops.

DannyX,

Measured the voltages at one layer of the connector (Pins 1 through 10)of connector CN201 from the power supply to the digital board. The voltages are stable, but...... they are completely out of specification per the troubleshooting guide.

Pin 1 = 13.7v and it must be 5V
Pin 3 = 19.08v and must be 5v
Pin 4 = 6.04v and must be 5v
Pin 7 = 6.04v and must be 18v
Pin 9 = 15.08v and must be 18v

It does not look good, but their might be a slim chance the digital board may not be cooked because their is some DC to DC converters on the board to do some dc regulation.

Maybe the switch mode converter on the power supply went sour. Maybe I take a gamble on this Jimmy kit :

https://www.shopjimmy.com/samsung-bn...repair-kit.htm

Thanks,

Martin
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Old 05-16-2019, 12:02 AM   #7
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

So is this your power supply board, BN44-00424A?
https://www.shopjimmy.com/samsung-bn...pply-board.htm
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Old 05-16-2019, 12:27 AM   #8
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Exclamation Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Quote:
Originally Posted by MAVA View Post
Measured the voltages at one layer of the connector (Pins 1 through 10)of connector CN201 from the power supply to the digital board. The voltages are stable, but...... they are completely out of specification per the troubleshooting guide.

Pin 1 = 13.7v and it must be 5V
Pin 3 = 19.08v and must be 5v
Pin 4 = 6.04v and must be 5v
Pin 7 = 6.04v and must be 18v
Pin 9 = 15.08v and must be 18v
Are you sure you measured the right pins ? That seems way off. You probably looked at the markings of the opposite row (the "even" row 2-4-6-etc.).
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Old 05-16-2019, 12:35 AM   #9
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Those readings must be errors, if you suppose to have 5V but you have 19V, something would have blown up big time. Probably pin count error.
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Old 05-16-2019, 01:05 AM   #10
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Budm,

yep that is the board.

About the readings, the readings were on the top layer of the connector which goes from 1 - 10(I read the silkscreen numbers) from the bottom to top, and pins 5 and 6 are ground. Pin 16 would not be a ground if it were wrong, so I really cannot be wrong... I will check tomorrow..

I think there is good chance that the board is not burned as their is some powerful switch-mode switching supply regulators on the digital board, and they will take a large input has been my experience. I will run a continuity form those high voltage inputs to the inputs of the switchers.. One can see the switchers pointed out on the trouble shooting PDF on the picture on page 4

I will check tomorrow..

My DVM is not cheap meter either, so I trust it like no other meter..

Thanks,

Martin
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Old 05-16-2019, 09:47 AM   #11
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Quote:
Originally Posted by MAVA View Post
Budm,

yep that is the board.

About the readings, the readings were on the top layer of the connector which goes from 1 - 10(I read the silkscreen numbers) from the bottom to top, and pins 5 and 6 are ground. Pin 16 would not be a ground if it were wrong, so I really cannot be wrong... I will check tomorrow..

I think there is good chance that the board is not burned as their is some powerful switch-mode switching supply regulators on the digital board, and they will take a large input has been my experience. I will run a continuity form those high voltage inputs to the inputs of the switchers.. One can see the switchers pointed out on the trouble shooting PDF on the picture on page 4

I will check tomorrow..

My DVM is not cheap meter either, so I trust it like no other meter..

Thanks,

Martin
IS this your main baord?
https://www.shopjimmy.com/samsung-bn...d6050tfxza.htm
I do not see pin 1 is labeled as 5V.
The CNM803 pin 1 of the power supply board is NC, the connector between power supply board and the Main board CN201 are not pin to pin.
"One can see the switchers pointed out on the trouble shooting PDF on the picture on page 4" may be you should upload the manual.
CN201: The exposed pins you see on the top side of the board are ODD number pin, as you can see pin1 on one end, pin 19 on another end, same for the CNM803.
That is why your reading are way off, you should measure them on the power supply side instead since they are labeled.
For example you measured 13V on pin 1 of CN201, that pin should go to CNM803 B13V (switched 13V) pins of the power supply board.
Pictures are worth 10,000 words.

Last edited by budm; 05-16-2019 at 10:26 AM..
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Old 05-16-2019, 10:08 PM   #12
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Here are the Pictures.

Okay, will get a measurements from the power supply side.

Martin
Attached Images
File Type: jpg IMG_7171.jpg (1,021.2 KB, 6 views)
File Type: jpg IMG_7172.jpg (971.8 KB, 2 views)
File Type: jpg IMG_7173.jpg (507.0 KB, 3 views)
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Old 05-16-2019, 11:17 PM   #13
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Okay got some measurements CN803, yet I only got the odd pins which contained 5v and 13v circuits. The voltages were stable, and looks like they are okay, yet the 13v side is a little low.

My Measurements:

1=N/C
3=12.73v
5=12.73v
7=19.05v
9=19.05v
11=GND
13=5.37v
15=5.37v

Martin
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Old 05-16-2019, 11:37 PM   #14
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

So how about the Voltages for the EVEN number pins? Since the Switched 13V and 19v are steady that means the PS-ON is steady, so we need to know the control Voltages for the backlights circuit which are on the even number pins, you can probe from the wire entrance side of the connector.
So far it does not look like the main power supplies are pulsing, may be the LED power supply section is the one that is pulsing or the control lines are pulsing.

Last edited by budm; 05-17-2019 at 12:47 AM..
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Old 05-16-2019, 11:55 PM   #15
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Looks good to me. Measure the other row as well just for confirmation. Could be a corrupted firmware at this point. I heard that unfiltered power or power spikes can cause corrupted EEPROMs, though this could just be a silly little electronics myth...
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Old 05-17-2019, 07:47 AM   #16
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Even side of voltages... look at the picture on post 13

2 = N/C-Empty slot-no wire
4= 68mV
6= 12.68v which should be N/C
8= 4.95v Fluctuates like every 5 to 10 sec from 0v to 4.95v
10= 0v from using pin 11 ground
12=0v from using pin 11 ground
14= 5.38v = Stable
16= 2.06v fluctuates like every 10 seconds. Seems slower in fluctuation than pin 8

The connector 802 going to the LED illumination on both pairs I get like 5mv, so obviously they are not on, and I tested right when I power up the set, yet like every 15 seconds the voltage fluctuates to a few 100mV for a few seconds then back down to 5mv to 3mV.

Looks like it is time to follow pin 8 and pin16 on the power supply board, and see what is faulty.

Martin

Last edited by MAVA; 05-17-2019 at 07:53 AM..
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Old 05-17-2019, 08:00 AM   #17
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Have you tested the PSU on its own like I previously suggested (by unplugging it from the main board) ? I forgot to ask whether your measurements were taken with or without the MB, but I believe you had the MB connected since you said pin 8 BLU_ON cycled high-low. With the main board disconnected, BLU_ON should stay high all the time and the backlight should also come be on.
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Old 05-17-2019, 08:21 AM   #18
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

All the measurements taken with everything connected. I will need to find some bulbs(or resistor loads).

I will have to try it later tonight.

Martin
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Old 05-17-2019, 10:40 AM   #19
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

For now you can just try it under no-load conditions. At least the backlight should come on.
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Old 05-17-2019, 11:43 AM   #20
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Default Re: Samsung Samsung UN55D6050TF-Power Supply Pulsing, I think.

Quote:
Originally Posted by MAVA View Post
Even side of voltages... look at the picture on post 13

2 = N/C-Empty slot-no wire
4= 68mV
6= 12.68v which should be N/C
BL-ON: 8= 4.95v Fluctuates like every 5 to 10 sec from 0v to 4.95v
10= 0v from using pin 11 ground
12=0v from using pin 11 ground
14= 5.38v = Stable
PS-ON: 16= 2.06v fluctuates like every 10 seconds. Seems slower in fluctuation than pin 8

The connector 802 going to the LED illumination on both pairs I get like 5mv, so obviously they are not on, and I tested right when I power up the set, yet like every 15 seconds the voltage fluctuates to a few 100mV for a few seconds then back down to 5mv to 3mV.

Looks like it is time to follow pin 8 and pin16 on the power supply board, and see what is faulty.

Martin
How much of the fluctuation of the Control Voltage on pin 16 (PS-ON)? I doubt that you have problem with this PS-ON control line from main board because the switched B13v and B5V are steady.
BL-ON pin 8 is the Backlights on control signal from the main board, since it is pulsing which is not right so the backlights circuit are being turning on and off.

Last edited by budm; 05-17-2019 at 11:44 AM..
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