Samsung TV Flickering on start up

[Newnies]

Hi all. I am 'the new guy' to this site. I stumble across this site awhile back while looking for some information on an Samsung TV. Really enjoyed reading everyone's input; which helped me repair that TV.

Now, I have a Samsung TV model- LN32D403E4DXZA version SP01 that had a bad power board among other issues. Power board's circuit from the main cap to the back light inverter blew and the board was damaged beyond repair. I got a replacement board (BN44-00438a) that failed while still testing the TV. I used the attached schematics (2 different schematic for this board. The board is a mix of both of them) to determine that the transistor located at QM854 was bad. After replacing it, the power board worked again.

Now, when the TV starts up, the back light flashes for about 20 seconds then stays on steady. The center 'weak or no signal' (I have no input attached) is somewhat bright, but dims in stages over the next 30 seconds. I reset the TV and updated the software, but this flickering and dimming still occurs. I don't have the ECO setting on. I am guessing it is the main board, but the high FET reading on my power board is lower than I think it should be.

I have searched your forums for information on this TV but came up short. I would love anyone's input on what the problem could be. If you know which component on the board might be an issue, please tell me that too.

Thanks in advanced for all your help!

We all love readings so here is what I have:

Power Board: (BN44-00438A)

Main Cap- 384.5-385.5V back light flickering / 387v when back light steady

CN1801 pinout: Back light flickering Back light steady
Pin 1 - High Fet - 187.8-191V 185V
Pin 3 - Low Fet 187-192V 185V
Pin 9 - OVP .10-.06V .004V
Pin 10 - CNT-PRT 12.4V 12.4V
Pin 11 - VCC 12.6V 12.6V
Pin 12 - LD 11.3V 11.3V

U1801 (Sem2106) chip
Pin 14- VCC - 12.2V
Pin 13 - N2 - .515V
Pin 12 - N1 - .681V

CN802 pinout
Pin 1,3,5,7 - B13V - 12.61V
Pin 11,13 -B5V - 5.23V
Pin 2 - P_Dim - .8V
Pin 4 -NC
Pin 6 - BLU_ON - 104-107mV
Pin 12 - A5V - 5.22V
Pin 14 - PS_ON - 3.5V
Pin 8,9,10 GND

Inverter Board (SST320-4UA01) (LJ97-03461A) Attached pic Shop Jimmy
Transformer:
Primary - 1.6 ohms
Secondary - .94 Kohms

IC U001 (BA10358 Dual GND Sense Op Amp) Pinout
Pin 1 - Out -1.2mV
Pin 2 - -In1 - 6.75V
Pin 3 - +In1 -.95V
Pin 4 - VEE - 0
Pin 5 +In2 - 6.28V
Pin 6 - -In2 - 1.5mV
Pin 7 - Out2 - 11.28V
Pin 8 - Vcc - 12.55V

[nomoresonys]

Re: Samsung TV Flickering on start up

Pin 6 - BLU_ON - 104-107mV Don't look good too low.

[Newnies]

Re: Samsung TV Flickering on start up

Would you happen to know what the voltage of Pin 6 should be?

[nomoresonys]

Re: Samsung TV Flickering on start up

You're checking with tv plugged in power button off which is standby, then you hit power button and get that reading too, they can vary but usually you need 2.5+volts which comes from the mainboard, which turns backlights on, at 107 mv seems too low to turn m on.

[nomoresonys]

Re: Samsung TV Flickering on start up

https://www.shopjimmy.com/samsung-bn...upply-unit.htm picture of powersupply

[nomoresonys]

Re: Samsung TV Flickering on start up

I would unplug powersupply from mainboard and do the jump with resistor to see if that voltage comes up, on this one I think you need to jump ps on with 5 volt standby and blu-on, better double check with one of the pros tho, to be sure.

[Newnies]

Re: Samsung TV Flickering on start up

Thank you for all the information. I re checked Pin 6 (Blu_on) and got 5.1V. My mistake.

On CN 1801, Pin 1 (High Fet) should it be higher than 185V?

[nomoresonys]

Re: Samsung TV Flickering on start up

I think it says high 280 on your board map/legend, seems low?