tv samsung UE55K5500AK no start

[madjid911]

Hi, I have a samsung tv that does not start at all, the red light is on, it flashes when I press the remote control, but the TV does not start

TV samsung model : UE55K5500AK
POWER SUPPLY : BN44-00872C L55E1_KSM REV 1.1
Motherboard : BN41-02534
T-CON : TT4851B01-1-C-3

Here are my tests :
-When I unplug the tablecloth from the motherboard, the LEDs light up
-I have 12v fine on the T-CON board, no shorts, fusible is good, no change when i unplug the t-con board.
-I did not find a dead or shorted component on the motherboard, the processor heats up normally.

My measurements on the power board:

Power supply without the motherboard
11 0v 12 0v GND

9 12V8 10 0v GND

7 12V8 8 4V5 PS-on

5 12V8 6 3V3 BLU_PWN

3 12V8 4 4V51 OD/UD

1 0v 2 3V59 OD_ON/OFF

Power supply with the motherboard
11 0v 12 0v GND

9 12V8 10 0v GND

7 12V8 8 3V3 PS-on

5 12V8 6 0V BLU_PWN

3 12V8 4 3V45 OD/UD

1 0v 2 3V58 OD_ON/OFF


Do you have an idea please?

[nomoresonys]

Re: tv samsung UE55K5500AK no start

Can you write that out again, having a hard time deciphering that style.

[madjid911]

Re: tv samsung UE55K5500AK no start

Can you write that out again, having a hard time deciphering that style.

My measurements on the power board:

Power supply without the motherboard
12 0v GND
11 0v
10 0v GND
9 12V8 10 0v GND
8 4V5 PS-on
7 12V8
6 3V3 BLU_PWN
5 12V8 6 3V3 BLU_PWN
4 4V51 OD/UD
3 12V8
2 3V59 OD_ON/OFF
1 0v

Power supply with the motherboard
12 0v GND
11 0v
10 0v GND
9 12V8
8 3V3 PS-on
7 12V8
6 0V BLU_PWN
5 12V8
4 3V45 OD/UD
3 12V8
2 3V58 OD_ON/OFF
1 0v

I don't understand why I don't have one even with the motherboard unplugged, is it the wrong pin?

[nomoresonys]

Re: tv samsung UE55K5500AK no start

CN9101 -____________OFF______ON
PIN 1 - +5V/+3.5V__5.12V_____5.14
PIN 3 - +12V -______19.17V___19.13
PIN 5 - +12V -______19.17V___19.14
PIN 7 - +12V_A _____19.17V___19.16
PIN 9 - GND -________0V______0
PIN 11 - GND ________0V______0
PIN 13 - 3D _________0V______0
PIN 15 - ON/OFF _____0.1V____3.22

CN9102 -
PIN 2 - +5V/+3.5V -__5.12V___5.14
PIN 4 - +12V - ______19.17V__19.16
PIN 6 - +12V - ______19.17V__19.14
PIN 8 - +12V_A -_____19.17V__19.16
PIN 10 - GND -_______0V______0V
PIN 12 - GND - ______0V______0V
PIN 14 - PS_ON -_____0.5V____3.68
PIN 16 - DIM -_______0V______3.27 Report it like that so it makes more sense.

[nomoresonys]

Re: tv samsung UE55K5500AK no start

So pin #, expected voltage, actual voltage when off, actual voltage when you power on, no need to report the grounds.

[madjid911]

Re: tv samsung UE55K5500AK no start

So pin #, expected voltage, actual voltage when off, actual voltage when you power on, no need to report the grounds.

ok thanks, sorry i am new to tv troubleshooting

I checked everything I did not find a dead or shorted component, it may be due to the backlighting, before you a solution to test the led bars without dismantling everything?

[nomoresonys]

Re: tv samsung UE55K5500AK no start

RJ touches on testing backlights in post 34 of this thread: https://www.badcaps.net/forum/showthread.php?t=116512

[madjid911]

Re: tv samsung UE55K5500AK no start

RJ touches on testing backlights in post 34 of this thread: https://www.badcaps.net/forum/showthread.php?t=116512

that didn't help me sorry,


1 NC =0
2 OD_ON/OFF =3.58V
3 A13V =12.8V
4 OD/UD =3.45V
5 A13V =12.8V
6 Blu_Pwm =0V
7 A13V =12.8V
8 Ps_ON /OFF = 3,3V
9 A13V =12.8V
10 GND
11 GND
12 GND

to be sure it's not the leds, I'd like to connect the stanby with the ps-on, but I'd like to know what signal is on the leds? Is it Blu_Pwm ? here I have 0v on Blu_Pwm, if it is the signal that triggers my leds then if I connect Blu_Pwm to ps-on, the leds should light up, right? I don't want to do anything stupid, I'm still a young beginner

[nomoresonys]

Re: tv samsung UE55K5500AK no start

Ok, now we can tell what the pins are, now unhook cable from powerboard to mainboard on powerboard side, plug power cord in, test each pin, just tell which pins have voltage and the amount like 3.3 etc, be careful to only touch one pin at a time with the probe.

[madjid911]

Re: tv samsung UE55K5500AK no start

Ok, now we can tell what the pins are, now unhook cable from powerboard to mainboard on powerboard side, plug power cord in, test each pin, just tell which pins have voltage and the amount like 3.3 etc, be careful to only touch one pin at a time with the probe.

here are the measurements without the motherboard. the backlight turns on.

1 NC =0
2 OD_ON/OFF =3.58V
3 A13V =12.8V
4 OD/UD =4.51V
5 A13V =12.8V
6 Blu_Pwm =3.3V
7 A13V =12.8V
8 Ps_ON /OFF = 4.5V
9 A13V =12.8V
10 GND
11 GND
12 GND

do you have an idea ? THANKS

[nomoresonys]

Re: tv samsung UE55K5500AK no start

Ok when you do that and the backlights come on and stay on, that usually means the backlights and powerboard are ok, try turning on tv with one cable unhooked from tcon to panel driver board, see if there's anything on display then do the other side same way, best policy is make all connections and dis-connections with tv unplugged from power to avoid any errant surges and such.

[madjid911]

Re: tv samsung UE55K5500AK no start

Ok when you do that and the backlights come on and stay on, that usually means the backlights and powerboard are ok, try turning on tv with one cable unhooked from tcon to panel driver board, see if there's anything on display then do the other side same way, best policy is make all connections and dis-connections with tv unplugged from power to avoid any errant surges and such.

yes that's the first thing I did, I connected and disconnected each tablecloth each but no change.

It's probably the motherboard that died, but I would have liked to know how to connect the ps-on to the stanby and also the backlight signal to be sure that the power supply board is good

[nomoresonys]

Re: tv samsung UE55K5500AK no start

Well looks like you have an always on powerboard and the voltages look good, so yep looks like a mainboard issue.

[nomoresonys]

Re: tv samsung UE55K5500AK no start

6 Blu_Pwm =3.3V seems to be the problem, when mainboard is connected it looks like the mainboard is keeping it low for some reason, maybe trace that line back thru the mainboard and see where it goes.

[madjid911]

Re: tv samsung UE55K5500AK no start

6 Blu_Pwm =3.3V seems to be the problem, when mainboard is connected it looks like the mainboard is keeping it low for some reason, maybe trace that line back thru the mainboard and see where it goes.

I followed in continuity blu_pwn on the motherboard, and I arrive at this component (k72), see photo, I can't find any shorts, Could the component be dead? I can't find it on the internet

[lotas]

Re: tv samsung UE55K5500AK no start

K72 - 2n7002

[Diah]

Re: tv samsung UE55K5500AK no start

Blu_Pwm its belong to BL. its normal to be high when MB disconnected so BL turn on.
you have firmware issue didn't start... check after it SPI and lotas the one who can check the dump content of it. in case there are spi

[madjid911]

Re: tv samsung UE55K5500AK no start

K72 - 2n7002

thank you , can i shunt the drain and gate to get my 3.3V?

[madjid911]

Re: tv samsung UE55K5500AK no start

Blu_Pwm its belong to BL. its normal to be high when MB disconnected so BL turn on.
you have firmware issue didn't start... check after it SPI and lotas the one who can check the dump content of it. in case there are spi

I had tried to find the firmware to flash the motherboard, but I did not find

[lotas]

Re: tv samsung UE55K5500AK no start

Dump spi (24Q40) I have for testing, but rather a problem with the eMMC firmware.