Un55mu630df

[Andrew F. Ali]

Re: Un55mu630df

Yes if I unplug the main board from PSU backlights come on and stay on.

This proves your PSU is good. I however, don't think it is a Main Bd. but think the issue is a missing or low Vcom voltage on the T-CON Bd.

[nomoresonys]

Re: Un55mu630df

Researched and found out it still can be powersupply, I didn't just pull that statement out of the air.

[budm]

Re: Un55mu630df

Hello I have a Samsung UN55MU630DF television. I have tested the power supply and getting good reading on my voltages. 12.2 and 3.34. I replaced the main board because initially it would not even come on. Now the back lights flash on and off in a cycle. No T-Con but did replace ribbons from main to panel.

The old board in place. What Voltage do you get on the power supply connector that goes to the main board?

[fcisolutions]

Re: Un55mu630df

Not sure what you mean by control voltages. The voltages going into the main board are all stable when everything is hooked up and the backlights are constantly cycling, at 12.7 volts. On the power supply pin 4 which is BO on/off will go from 0 up to 3.4 as the t.v. cycles.

[nomoresonys]

Re: Un55mu630df

Check voltage of CP810S and CP814S, on powersupply, put meter leads on the legs, measure in standby and with power button activated, simple test.

[budm]

Re: Un55mu630df

Control signals:
Pin 2: ANA_DIM (Analog Dimming control)
Pin 4: OD_ON/OFF (BL-ON: Backlights on/off)
Pin 6: BLU_PWM (PWM Dimming control)
Pin 8: PS-ON (Main power supply ON/OFF)

So which one is not stable? Pin 4?

[fcisolutions]

Re: Un55mu630df

O.K. so I can't really put the t.v. in standbye because it seems to cycle on and off or at least the backlights flash on and then off. The capacitors on PC810S and CP814S top out at 391V. The control signals are
Pin 4 stable @ 3.4V
Pin 6 goes 1.1V to 0V
Pin 8 goes 3.4V to 0V

[budm]

Re: Un55mu630df

OK, so your main board is toggling PS-ON ON and off so the power supply is then toggling on and off which will cause the backlights to flash.
So how about request on post 23?

[fcisolutions]

Re: Un55mu630df

When I hook up the old main board the only voltages I get are on pins 3,5,7, and 9 at 12.7 V. No backlights come on. Standby is 12.7 also.

[budm]

Re: Un55mu630df

So none of the control signals are there at all.
Where did you get the replacement board from?

[fcisolutions]

Re: Un55mu630df

Replacement board I got on ebay, it does have a return. But yes on the original board no other readings.

[CapLeaker]

Re: Un55mu630df

You must have gotten a bad replacement main board. Ebay stuff is always a gamble.

[nomoresonys]

Re: Un55mu630df

Wonder if its a bad IC on the mainboard, did you locate a service manual?

[nomoresonys]

Re: Un55mu630df

While I had two mainboards to look at, I would test everything you can like the voltage regulator ICs fuses etc, on both of them, see if you have any differences in readings.