LG 55UF6450 Power Supply Pinout Voltage Question

[Tjp444]

I've been working on this 4K tv, it starts but turns of and off, the logo never comes up. I've done a lot of TV's but this one was a mystery. Seemed like a main board issue, replacing that with one I am 98% sure is good, TV acts the same. I started looking at the power supply and I'm trying to figure out which pins are supposed to be putting out what. I've never seen the attached diagram style before, can anyone assist? I downloaded the service manual but it doesn't show the voltages at the various connectors.

I'm getting 8v on several pins, just for a fraction of a second the voltmeter reads 13v and then it drops. The voltmeter is good, the ground is good, could this be the PS is dropping under load or am I introducing a measurement error? Thanks for any input.

[budm]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

Left column is for odd number pins:
Pin 1 = PWR-ON (PS-ON)
Pin 3 = GND
Pin 5 = 13.2V
Pin 7 = 13.2V
Pin 9 = GND
Pin 11 = DRV-ON (BL-ON)

Right column is for EVEN pins
Pin 2 = P-DIM2
Pin 4 = 13.2V
Pin 6 = 13.2v
Pin 8 = 13.2V
Pin 10 = GND
Pin 12 = P-DIM1

[Tjp444]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

Thanks a lot Bud, that's a huge help.

[datas]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

I also have the same problem, on the connector I always have 8v instead of 13v. Have you found a solution?

[nomoresonys]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

http://www.shopjimmy.com/lg-eay64009...iver-board.htm clear pic.

[budm]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

Is the PS-ON present when TV's power switch is activated?
PS-ON <1VDC = TV OFF
PS-ON >2 ~ 2.5VDC = TV ON.

[Tjp444]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

Well, to answer Bud's question, yes, on my TV the on voltage is there all the time, and it has done that with both main boards I have tried. I bought a replacement power supply, the pattern on the screen changed but it still doesn't work (no picture or menu). I swapped the Tcon, that changed the picture (from one dark band down the middle to just blank) but it still doesn't work. It has become my great white whale. Saturday I'm picking up another one that still works but has a cracked screen. Hopefully this will provide me with a supply of parts that I can swap out and figure it out. Saturday I'm picking up another one that still works but has a cracked screen. Hopefully this will provide me with a supply of parts that I can swap out and figure it out. I will post again when I have done that. I don't need the TV it's just become a quest.

Sorry for any typos I'm writing this from my phone.

[freakaftr8]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

Have you tried the one tcon cable at a time trick?

[Tjp444]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

No I haven't, I've never even heard of it. I take it it's self-explanatory? What info should that yield?

[freakaftr8]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

How many ribbons go from the tcon board to the LCD panel? If only two, disconnect the right side and power up. See if one half of the screen works. If not reverse the process w the other side.

[Tjp444]

Re: LG 55UF6450 Power Supply Pinout Voltage Question

Yes there are 2 going to the panel. Thanks, I'll try it in the morning.