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Aric
Aric, Technician
Category: TV
Satisfied Customers: 41937
Experience:  15+ years in the field. Owner of AV Installation, OEM and Repair company
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I have a LG 55lk520 tv that turns on ok but after powering

Customer Question

I have a LG 55lk520 tv that turns on ok but after powering up the screen blinks on and off three times and goes black and the power light blinks a steady red. I took the back off and tested the outputs on the power supply board and everything seems ok. Where do I go from here
Submitted: 6 months ago.
Category: TV
Expert:  Aric replied 6 months ago.

Hello, How exactly did you test the outputs of the power supply (we see many people do this wrong)?

Also did you test them AFTER the screen goes black and the power light blinks a steady red?

Customer: replied 6 months ago.
I tested it BEFORE the screen goes black and the power light blinks .......to test it i put the ground lead of my volt meter on the framework the board is mounted to and back probed the connectors on the board with the positive lead. All the readings lined up with the voltagesame indicated beside the connectors
Expert:  Aric replied 6 months ago.

What you need to do is test after the screen goes black now and find out what voltages are present.

Expert:  Aric replied 6 months ago.

Offhand it would appear that your power supply/inverter has failed and is not able to provide consistent power to the CFFL's in the screen. This can also be caused by failing lamps in the screen itself ,but is most commonly the power supply failing under load. So your backlight voltage- does that flicker or change along with the screen?

Expert:  Aric replied 6 months ago.

Specifically the 24 VDC output from the supply board- is that steady up until the light goes back to red?

Expert:  Aric replied 6 months ago.

Actually seeing you have two inverter boards between the power supply board and your screen. Unplug the two inverter boards, then run that voltage test again. Tell me if the power light stays on.

Expert:  Aric replied 6 months ago.

These guys here- if your power board is shutting down, and your screen flickers a few times before the power light turns red, then these are the boards you would need to replace in most cases. Simply unplug the set from power then disconnect the two inverter boards, see if the set stays powered up (nothing on the screen but steady voltages remain present):

http://www.shopjimmy.com/lg-6632l-0613a-6632l-0614a-backlight-inverter-kit.htm

Expert:  Aric replied 6 months ago.

Feel free to reply back if you need more help, or want to reply back with more details. It does not cost you anything more to reply back once you've rated. Please do rate me positively (at least 3 STARS) and I will continue with you on this as needed. The positive rating ensures I am credited for my work.

Customer: replied 6 months ago.
I am attaching a photo of the left inverter board the component to the left is considerably hotter than the one to the right is that normal or does that indicate a possible problem. Both on the right board are as cool as the one on the right
Expert:  Aric replied 6 months ago.

They should be the same temp- as they do the exact same job (light equal portions of the screen). Did you disconnect them both to see if the power light and voltages stay on??

Expert:  Aric replied 6 months ago.

If the voltages stay present with the inverters disconnected, then your inverters need to be replaced. They're available at that link for just under $40.

Expert:  Aric replied 6 months ago.

If you need further assistance let me know. Please do not forget to click at least a 3 STAR RATING, at the top of the page for my efforts. That is how the site credits me for my work.

Customer: replied 6 months ago.
It does the same thing with them unplugged
Expert:  Aric replied 6 months ago.

Then you would want to replace your power supply board as it's shutting down and is the root cause of the issue.

Expert:  Aric replied 6 months ago.

Hello, I was just following up to see if you needed further help. The site shows that since the question is open that you are still looking for help. Or, if you received the information you were looking for- please kindly RATE my service POSITIVELY to reflect that. Thank you.