LG55LF6000UB - Cycles Off and On

[1beertap]

Hello,

i have a 55LF6000 LG tv that cycles off and on when turned on. I have unplugged the LED strips and using a light to look at the display, I noticed that the tv is still cycling off and on. My thoughts are power supply or main board is the problem. The voltages for the power rails are not clearly identifiable. Any ideas? Thanks.

[budm]

Re: LG55LF6000UB - Cycles Off and On

Hello,

i have a 55LF6000 LG tv that cycles off and on when turned on. I have unplugged the LED strips and using a light to look at the display, I noticed that the tv is still cycling off and on. My thoughts are power supply or main board is the problem. The voltages for the power rails are not clearly identifiable. Any ideas? Thanks.

"The voltages for the power rails are not clearly identifiable" What does that mean?
https://www.badcaps.net/forum/attach...5&d=1574711337
P201 has label for each pin to tell you what each pin is for.

[nomoresonys]

Re: LG55LF6000UB - Cycles Off and On

Try with tv unplugged from power, unhook cable from powerboard to mainboard, leave it unhooked, plug power cord into powerboard, see if it still cycles, and test P201, the expected voltages are right beside it see the little legend/map? as always BE CAREFUL when working with powerboard, the HOT side has DEADLY VOLTAGE, P201 is on the cold side.

[1beertap]

Re: LG55LF6000UB - Cycles Off and On

Thanks for replying so fast. I figured out the legend, sorry for the confusion. Here are my readings:

PWR-ON = 3.18v
GND = OK
13.2V = 13.1v
13.2V = 13.1v
GND = OK
DRV-ON = 3.25v

PDIM1 = 1.11v
GND = OK
13.2V = 13.1v
13.2V = 13.1v
13.2V = 13.1v
PDIM2 = 1.16v

[nomoresonys]

Re: LG55LF6000UB - Cycles Off and On

Those look ok to me, do you have those steady voltages while the tv is cycling?

[1beertap]

Re: LG55LF6000UB - Cycles Off and On

Those look ok to me, do you have those steady voltages while the tv is cycling?

Yes

[budm]

Re: LG55LF6000UB - Cycles Off and On

So you are 100% sure that the PWR-ON = 3.18v is steady at 3.18V and not swinging between <1V and >3V.

[nomoresonys]

Re: LG55LF6000UB - Cycles Off and On

Heat up the mainboard with a hairdryer, the whole thing, be sure n hit those black chips too, then turn it on and see if it acts any different, even for a little while.

[1beertap]

Re: LG55LF6000UB - Cycles Off and On

So you are 100% sure that the PWR-ON = 3.18v is steady at 3.18V and not swinging between <1V and >3V.

yes, it is steady while the backlight and display cycles off and on.

[1beertap]

Re: LG55LF6000UB - Cycles Off and On

i will try heating the entire board and gently tap on those said chips.

[1beertap]

Re: LG55LF6000UB - Cycles Off and On

Heat up the mainboard with a hairdryer, the whole thing, be sure n hit those black chips too, then turn it on and see if it acts any different, even for a little while.

It made no difference.

[1beertap]

Re: LG55LF6000UB - Cycles Off and On

With steady voltages coming from the power supply, I'm thinking the problem is on the main board. Any thoughts?

[nomoresonys]

Re: LG55LF6000UB - Cycles Off and On

CLean the contacts, ribbon cable ends going from tcon to panel and lvds cable going from tcon or panel driver to mainboard and make sure the connections are secure not loose or anything.

[nomoresonys]

Re: LG55LF6000UB - Cycles Off and On

If it's cycling like this, could be the backlight led problem, might want to do some more testing before taking it apart tho being it's 55 inches and the panels are VERY easy to break, if the panel breaks it's game over and put the proper voltage led in, actually best policy is replace all the strips, don't do like he did, lol: https://www.youtube.com/watch?v=Q46Y7HZW9ck