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Aric, Technician
Category: TV
Satisfied Customers: 44897
Experience:  15+ years in the field. Owner of AV Installation, OEM and Repair company
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My LG 50" 50PG20 wont turn on.

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My LG 50" 50PG20 won't turn on.
Hello and thank you for the question. How long have you had the set for and when did the problem occur?

Was it after a storm or power outage?

Additionally what prompted you to replace the Sustain boards?

What exactly does the TV do, or not do when you attempt to power it up?
Customer: replied 3 years ago.

Had the set 5 years. Problem occured about a month ago. We did have a power outage and then a surge when the power came back on. The TV worked for a couple of days after that.


I went on line and read some stories of other people who had the same problem and resolved it by replacing the sustain boards. I replaced the ZSUS first. That didn't resolve the problem so I replaced the YSUS board.


When I power the TV up, I think the green light blinks 3 times than stays on for a few seconds, then turns to red.


What do you think?


Thanks, Packard

Thank you. I think that before replacing the Sustain boards, you would want to measure the outputs of the power supply using a Meter, as the Power Supply is a more common failure for this type of problem. Do you have a meter and the ability to measure live voltages?

Also, when you press power, does the screen attempt to light up even for a second?
Customer: replied 3 years ago.

Thanks Aric,


Yes, I have a meter. Is the power supply right where the power cord plugs in? What should the values be and where do you hook to?


Thanks, Packard

Please only proceed if you have experience measuring live voltages on a circuit board level.
Use a DVM (Digital Volt Meter) set to DC volts, put the Black probe of the Meter on an RCA jack shield on the back of the TV, then use the Red probe and probe all of the Outputs for voltage (correct voltages will be stamped on the power supply at the outputs). Make sure you check specifically also for the "Va" and "Vs" voltages, as these drive the Sustain boards, and in turn the Panel.

Do this with NOTHING connected to the Power supply but AC power, the Mainboard, and the little board that houses the Power Switch. If a voltage is missing/ fluctuating, then the power board needs to be replaced.

Let me know what you find please.
Customer: replied 3 years ago.

OK ....... The jack shield is the outside of the RCA jack right?


The outputs are the center hole on the jacks ..... correct?


What is the Va & Vs voltage?


How do I identify the power supply?


If it turns out it's the power board, any suggestions where to buy one?


Thanks, Packard

No, you're not on the right track here. RCA jacks are on the mainboard, and i was simply asking you to grab a ground from there. Instead, put the black probe on any metal part of the chassis inside the TV. Then measure the "Power Supply" Outputs. Look for silkscreened lettering on the pins of the power supply that say Va and vs next to them.
Customer: replied 3 years ago.

Thanks Aric, I'll give your advise a try and if I have more questions, I'll ask for you. I'll let you know how I make out ....... Packard

That sounds goods Packard, and in most cases it is the power supply board, but the only way to isolate it for sure is to check the voltages off of this board and see if there are missing voltages. if you find that the board is bad, then you can locate replacements at: or even

If you need further assistance let me know and please do not forget to rate my service accordingly.
Aric and 4 other TV Specialists are ready to help you
Customer: replied 3 years ago.

Hi Aric,

I think you put me on the right path. I checked those voltage values on the power board and they are real low, like 1/2 a volt. So I found a place on line located in Texas that will repair the power board for about $70. Thanks again for your help. I wish I had known about your service before I had invested in a YSUS board and a ZSUS board. Packard

Thanks for the reply Packard, and glad to hear it sounds you've sorted it. If you need anything further, please let me know.