Samsung UN75F6300AF Won't Power Up

[toddw65]

I picked up this monstrous Samsung unit today where the owner said the house had been hit by lightning. I can't see anything obviously burnt or blown.

On CNM803 I get 5.34V on pin 18 and .25V on pin 20. Nothing on any other pins.

Also, when I disconnect the harness between the main board and the power board, the LEDs all light up and the screen is nice shade of blue.

Thoughts?

[tvtimmy]

Re: Samsung UN75F6300AF Won't Power Up

Mainboard is bad.

[budm]

Re: Samsung UN75F6300AF Won't Power Up

So the backlights come on and stay on when the power supply board is not connected to the main board, that means the power supply board and the LED backligts are OK but the main board is the problem.
More like the surge came through the HDMI ports or cable port.

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

Ok. Thank you both.

[tvtimmy]

Re: Samsung UN75F6300AF Won't Power Up

Check ebay quick. Only a few to buy and only 1 cheap one. 1 is going for $200+.

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

Snagged this one. Fingers crossed.

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

Well, some progress... I think. Got the main board today and put it in. Now, when I hit the power button, relay RL801S on the power board clicks and then ~2 seconds later clicks again and with that last click, the backlight leds all flash for just a split second.

Hopefully the voltages below taken from CNM80 make sense. I've included the voltage initially and then the drop during the 2 seconds between the relay clicks. Most measurements drop to zero. A couple don't have time to drop all the way to zero and the 5V on pin 12 doesn't drop. Hopefully that makes sense and the formatting works.

Edit to add that once the cycle starts, it continues until the TV is unplugged.

Initial V	V during 2 seconds	Pin	  Pin	  Initial V	  V during 2 seconds
3.3	    0	        20	  1	  3.3	      0.13
1.03	    0	        19	  2	  1.79	  0
0.99	    0	        18	  3	  0	      0
0.89	    0	        17	  4	  12.56	  0
0	    0	        16	  5	  12.56	  0
0.15	    0	        15	  6	  19.93	  13.9
0	    0	        14	  7	  19.93	  13.9
0	    0	        13	  8	  0	      0
5.32	    5.32	        12	  9	  5.32	  0
3.3	    0.25	        11	  10	  5.32	  0

[budwich]

Re: Samsung UN75F6300AF Won't Power Up

I would suggest you put pin labels on the your "chart" as trying to figure out what the picture says versus what you charted seems less than obvious.... it would certainly help those who are trying to help without "mashing their brains"... :-)

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

Well now that I look at what I posted, no wonder it's confusing. I tried to get crafty and totally screwed up the pin numbers. Sorry about that. I'll post a less crafty update shortly.

[budwich]

Re: Samsung UN75F6300AF Won't Power Up

☺

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

Ok. Attaching it as a picture. Lets see if this is better.

[budwich]

Re: Samsung UN75F6300AF Won't Power Up

better but I don't think you are there yet... where are the pin "labels". Look if its too much effort for you to do, then think about how much effort it is for someone who might be trying to help you out in their "spare time".

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

That was in my very first post. Attaching together to avoid confusion.

[budm]

Re: Samsung UN75F6300AF Won't Power Up

Sorry. So I click on the pictures of the chart, then click on the pictures of the board, after 10 times of clicking back and forth to see what each pin is and Voltage are for each I gave up.
And BTW pin 1 and pin 3 is labeled as N.C. (No connection) so I do not expect to see the Voltages on those two pins.
Pin 12 blu-on/off signal is stuck LOW = No backlights.
At this point with the info on post 2 and 3, we know which board is the problem.

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

Sorry Bud. I promise I wasn't trying to be a pain in the butt.

Two questions: Am I safe to assume that the arrow is pointing to pin #1 on CNM803?

And so you'd say that I likely purchased a bad main board?

[budm]

Re: Samsung UN75F6300AF Won't Power Up

Sorry Bud. I promise I wasn't trying to be a pain in the butt.

Two questions: Am I safe to assume that the arrow is pointing to pin #1 on CNM803?

And so you'd say that I likely purchased a bad main board?

Arrow = Pin 1.
The exposed pins you see on the top side of the board are the ODD number pins, to get to the EVEN number pins you have to probe from the backside of the connector using skinny probe tip or probe on the bottom side of the board.

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

Ok. That's what I assumed all along but the voltages on pins 1 & 2 threw me. Maybe this new main board actually bad because I've double and triple checked and then checked again and the voltages are correct.

I also updated to show the voltages/pin/labels all together.

[CapLeaker]

Re: Samsung UN75F6300AF Won't Power Up

BLU_on off 0.15V. That is generated on the main board. So you got a bad main board here.

[toddw65]

Re: Samsung UN75F6300AF Won't Power Up

First main board I bought was apparently bad. Another board and the TV is back up and running. Thanks for you help on this one guys.

[Andrew F. Ali]

Re: Samsung UN75F6300AF Won't Power Up

That's great you got your TV going again but I still think you did not understand when we said we wanted the Pin Nos. and their labels. So what we wanted as an example:
Pin 1 N.C.: 0V
Pin2 std-by: 3.3V
Pin3 bl-on: 2.5V
and so on.
Probably you may get it right on your next repair question.