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Old 12-02-2015, 03:14 PM   #1
CraigR
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Default Samsung UN24H4000AF red blinking

Samsung UN24H4000AF LED tv whn turned on the front light either stays on steady and pushing the power blinks a few times then goes out. Never any backlight and nother ever on screeen using flashlight. I get 165v constant at the big cap and the 5 wire cord from the power to main I get 12.3v on 4 and ground on the other and does not matter if red light is on or off in front. I was thinking the main but am not sure what to test next. Thanks in advance for any help!
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Old 12-02-2015, 03:35 PM   #2
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Default Re: Samsung UN24H4000AF red blinking

Measure on the PSU the CNM803 connector all pins and post them. Then disconnect the main board and plug the TV in, the backlights should come on.
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Old 12-02-2015, 03:47 PM   #3
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Default Re: Samsung UN24H4000AF red blinking

Yes that's the connector I was talking about it's actually 12.9volts pin 1-4 then 5 is nothing. Unplugging that connector then powering the board still no backlight so Power board shot?
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Old 12-02-2015, 04:50 PM   #4
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Default Re: Samsung UN24H4000AF red blinking

O.k. maybe the PSU doesn't have a pull up resistor to fire up the backlights. I haven't seen a schematic for it.
You wont see more than 170V on the main filter cap, as the PSU is not getting turned on (no PSon) and thus the PFC isn't working. With the PFC working, voltage on the main filter cap is >360V DC.

Nothing on pin5 is bad. That defiantly indicates a bad main board. I guess you need a new replacement board. You could try to trace back the PSon signal on the main board, but I had not much luck fixing an issue like that as mostly the main IC was bad.

You can try to unplug the PSon pin from the connector and jump 13V DC through a 1k resistor on it and force the PSU on?

Last edited by CapLeaker; 12-02-2015 at 04:53 PM..
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Old 12-02-2015, 05:24 PM   #5
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Default Re: Samsung UN24H4000AF red blinking

You need to report the readings of all 10 pins and follow each pin with pin names per chart as printed on the board: CONNECTOR:CNM803.
Per chart:
PIN 1, 3, 5, 7 are A13V (Always on 13V)
PIN 8, 9, 10 are GND
PIN 2: OD_UD
PIN4: BLU_PWM
PIN 6:PWR ON/OFF

The ODD pins can be access form the top side of the board.
The EVEN pins are accessed from the bottom side of the board.

This power supply does not have PFC Voltage booster due to low power and it only has only one transformer and it is always running.
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Last edited by budm; 12-02-2015 at 05:36 PM..
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Old 12-10-2015, 01:27 PM   #6
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Default Re: Samsung UN24H4000AF red blinking

Well CapLeaker bad guess. Got the new main today and same thing. Even went as far as taling the LED's out and testing them. Wish I would have seen budm's post before I ordered it. Out $25
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Old 12-10-2015, 01:53 PM   #7
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Default Re: Samsung UN24H4000AF red blinking

1,3,5,7 are all 12.9v
2=3.2v
4=1.5v
6=5.4v
8,9,10 are good ground.
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Old 12-10-2015, 02:35 PM   #8
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Default Re: Samsung UN24H4000AF red blinking

Quote:
Originally Posted by CraigR View Post
1,3,5,7 are all 12.9v
2=3.2v
4=1.5v
6=5.4v
8,9,10 are good ground.
So 2, 4, and 6 change state when the power switch is toggle ON and OFF?
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Old 12-10-2015, 02:42 PM   #9
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Default Re: Samsung UN24H4000AF red blinking

Samsung BN44-00746A
BTW, you need to check the DCV of the LED connector CNL802 pins with and without the connector in place when TV is ON. I have a feeling you have bad LEDS.

Last edited by budm; 12-10-2015 at 02:44 PM..
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Old 12-14-2015, 02:44 PM   #10
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Default Re: Samsung UN24H4000AF red blinking

No change in voltage when on/off button toggled in 2,4 and 6
I have 18V on the LED connector. I removed the LED's and tested each bulb with a bench power source and all of them lit. I also noticed the led in the digital audio connector always stays on when toggling the on/off switch.
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Old 11-12-2019, 07:23 AM   #11
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Default Re: Samsung UN24H4000AF red blinking

Can I check the power without other boards?
What to include on the PowerOn?
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Old 11-12-2019, 07:43 AM   #12
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Default Re: Samsung UN24H4000AF red blinking

In what way is your tv malfunctioning vankbg? be as specific as you can.
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Old 11-12-2019, 08:22 AM   #13
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Default Re: Samsung UN24H4000AF red blinking

No power. Red LED is not illuminated.
Board power supply - checked, MOS, Diode ,.
There are 375 V input capacitor.
There is no output voltage.
I measure when the power circuit is disconnected from the TV.
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Old 11-12-2019, 08:32 AM   #14
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Default Re: Samsung UN24H4000AF red blinking

Don't understand "I measure when the power circuit is disconnected from tv". Did you try disconnect cable from powerboard to mainboard leave it out, then plug power cord into powerboard, do backlights come on and stay on?
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Old 11-12-2019, 08:45 AM   #15
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Default Re: Samsung UN24H4000AF red blinking

I measure when the power board is disconnected from tv(Mother board and LED) Only Power 220V
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Old 11-12-2019, 08:49 AM   #16
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Default Re: Samsung UN24H4000AF red blinking

Power suppay works without you plug to Mother board?
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Old 11-12-2019, 09:36 AM   #17
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Default Re: Samsung UN24H4000AF red blinking

It's a test to try to verify powerboard and backlights, don't be afraid no harm if done as instructed.

Last edited by nomoresonys; 11-12-2019 at 09:40 AM..
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Old 11-12-2019, 01:01 PM   #18
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Default Re: Samsung UN24H4000AF red blinking

Many thanks for your attention @nomoresonys !!!
I repaired the power supply.
The problem was PHOTOCOUPLER LTV-817B.
I changed and everything is fine!
Once again many thanks and all good!
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Old 11-12-2019, 01:26 PM   #19
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Default Re: Samsung UN24H4000AF red blinking

Good to hear, thanks for the feedback.
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Old 02-18-2020, 09:00 AM   #20
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Default Re: Samsung UN24H4000AF red blinking

Dear budm, can you help me?
My TV(Samsung UE40JU6400W) still illuminated RED standby LED on front. The voltages on powersupply are:
when mainboard is unplugged - connector CNM803 (then the LED backlight is switched on)
1. F/C 0,26V
2. A/D 2,67V
3. A13V 12,7V
4. OD_UD 3,53V
5. A13V 12,7V
6. BLU_PWM 3,11V
7. A13V 12,7V
8. POWER ON/OFF 3,86V
9. A13V 12,7V
10. GND 0V
11. GND 0V
12. GND 0V

If I connect mainboard then the backlight is turned off and there are those voltages:

1. F/C 3,20V
2. A/D 3,26V
3. A13V 9,28V
4. OD_UD 0,0V
5. A13V 9,28V
6. BLU_PWM 0,0V
7. A13V 9,28V
8. POWER ON/OFF 0,9V
9. A13V 9,28V
10. GND 0V
11. GND 0V
12. GND 0V

Is it bad mainboard, inst it?
Thank you,
Juraj
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