Hello,
I have a Samsung LN52B750U1FXZA LCD TV that isn't turning on. When plugged in all I am getting is a steady red standby light but nothing else. I do get a quick flash from the center LED that lights up the "Samsung" lettering on the front of the TV when I first plug the TV in and when I unplug it as well.
My mainboard: BN94-02585L (barcoded sticker) or BN41-01149B (printed on the board itself)
Power supply board: BN44-00287A
Observations:
When I unplug the main board from the power board the backlight turns on.
When the TV is plugged in, the transformer on the power supply board has a "hum" that lasts about 5 seconds then goes away for about 3 seconds. This repeats until I unplug the TV. While the power supply is connected to the main board, the POW ON_OFF pin cycles from ~19mV (while I hear the hum) then jumps to about 2.1v (when the hum stops) but only stays there for a split second.
When power supply is not connected to main board the hum is constant.
Pin readings when power supply is NOT plugged into main board (Only even pin#'s with a wire connection is Pin#2 and Pin#30):
1 POW ON/OFF: .800V
2 H_SYNC: 4.1mV
3 STB 5.3V: 5.33V
4~6 GND: 0
7~8 13 VS: 13.07V
9~12 GND: 0
13~16 5.3V: 5.33V
17~18 GND: 0
19 13Vm: 13V
20 GND: 0
21~22 13Vm: 13V
23 INV ON/OFF: 5.25V
24 NC: N/A
25 E-PWM: 5.33V
26 GND: N/A
27 DET_5V: 5.33V
28~30 GND: 0
Pin readings when power supply IS plugged into main board (Only even pin#'s with a wire connection is Pin#2 and Pin#30):
ALL (#V > 0) MEANS THAT IT CYCLES FROM THE VOLT# DOWN TO PRACTICALLY 0. This cycle coincides with the transformer humming on and off.
1 POW ON/OFF: 1.5v > 0V
2 H_SYNC: 0v
3 STB 5.3V: 5.33v
4~6 GND: 0
7~8 13 VS: 13v > 0
9~12 GND: 0
13~16 5.3V: 5v > 0
17~18 GND: 0
19 13Vm: 13.1V > 0
20 GND: 0
21~22 13Vm: 13V > 0
23 INV ON/OFF: 0V
24 NC: N/A
25 E-PWM: 4058 > 0
26 GND: N/A
27 DET_5V: 2.7V > 0
28~30 GND: 0
My first thought was a main board problem since I am getting proper voltages from the power board when the power supply is not connected to the main board and the back lights are lighting up. I bought a main board online but that did not solve my problem. I am assuming that the main board I bought is working properly and that is actually the power supply that is giving me issues.
Is there anything other troubleshooting things I can try to pinpoint this a little better. Also, if it is the power supply, do any of you have an idea as to what might be giving me this issue? I don't have any noticeable burns, marks on the power board.
I have a Samsung LN52B750U1FXZA LCD TV that isn't turning on. When plugged in all I am getting is a steady red standby light but nothing else. I do get a quick flash from the center LED that lights up the "Samsung" lettering on the front of the TV when I first plug the TV in and when I unplug it as well.
My mainboard: BN94-02585L (barcoded sticker) or BN41-01149B (printed on the board itself)
Power supply board: BN44-00287A
Observations:
When I unplug the main board from the power board the backlight turns on.
When the TV is plugged in, the transformer on the power supply board has a "hum" that lasts about 5 seconds then goes away for about 3 seconds. This repeats until I unplug the TV. While the power supply is connected to the main board, the POW ON_OFF pin cycles from ~19mV (while I hear the hum) then jumps to about 2.1v (when the hum stops) but only stays there for a split second.
When power supply is not connected to main board the hum is constant.
Pin readings when power supply is NOT plugged into main board (Only even pin#'s with a wire connection is Pin#2 and Pin#30):
1 POW ON/OFF: .800V
2 H_SYNC: 4.1mV
3 STB 5.3V: 5.33V
4~6 GND: 0
7~8 13 VS: 13.07V
9~12 GND: 0
13~16 5.3V: 5.33V
17~18 GND: 0
19 13Vm: 13V
20 GND: 0
21~22 13Vm: 13V
23 INV ON/OFF: 5.25V
24 NC: N/A
25 E-PWM: 5.33V
26 GND: N/A
27 DET_5V: 5.33V
28~30 GND: 0
Pin readings when power supply IS plugged into main board (Only even pin#'s with a wire connection is Pin#2 and Pin#30):
ALL (#V > 0) MEANS THAT IT CYCLES FROM THE VOLT# DOWN TO PRACTICALLY 0. This cycle coincides with the transformer humming on and off.
1 POW ON/OFF: 1.5v > 0V
2 H_SYNC: 0v
3 STB 5.3V: 5.33v
4~6 GND: 0
7~8 13 VS: 13v > 0
9~12 GND: 0
13~16 5.3V: 5v > 0
17~18 GND: 0
19 13Vm: 13.1V > 0
20 GND: 0
21~22 13Vm: 13V > 0
23 INV ON/OFF: 0V
24 NC: N/A
25 E-PWM: 4058 > 0
26 GND: N/A
27 DET_5V: 2.7V > 0
28~30 GND: 0
My first thought was a main board problem since I am getting proper voltages from the power board when the power supply is not connected to the main board and the back lights are lighting up. I bought a main board online but that did not solve my problem. I am assuming that the main board I bought is working properly and that is actually the power supply that is giving me issues.
Is there anything other troubleshooting things I can try to pinpoint this a little better. Also, if it is the power supply, do any of you have an idea as to what might be giving me this issue? I don't have any noticeable burns, marks on the power board.
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