Question about LG 42" 5700 Series LED HDTV - 42LN5700

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LG LED SmartTV is power on/off looping. Can I use the TV's PSB to power a cooling fan?

The only solution I have seen so far that has fixed the infinite power loop issue has been a firm whack the area just above the power input on the back of the TV where the PSB resides. This leads me to believe there is an electromechanical contact that is occasionally malfunctioning. I want to add a fan to the CPU and power supply, as well as an exhaust fan where the vent on the back panel is pre-cut (which makes you wonder why they didn't just put a fan there in the first place). I realize it is likely not advisable, but I was wondering if anybody has had success running a 12V pc cooling fan with a relay off the TV's PSB. Help me brainstorm!

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  • Austin Andres
    Austin Andres Nov 16, 2013

    I suppose the smarter thing to do would be to run an externally, or USB-powered, fan and a smart, auto-switching surge protector.

  • Austin Andres
    Austin Andres Nov 16, 2013

    I suppose the smarter thing to do would be to run an externally, or USB-powered, fan and a smart, auto-switching surge protector.



6 Suggested Answers

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Posted on Jan 02, 2017

  • 1554 Answers

SOURCE: LG 42KK Power Supply Schematic Requested

you won't find any just ,

use a thermal probe or thermal gun as heat is likely the issue ,
if nothing else replace the main diode /rectifier and caps.
I find that if I replace the hottest items that usually the fix

if there is room for a small fan you will be doing them a great service and extend the life of the tv.

you may find some info on the power supply from one of these links they are generic enough

Posted on Jun 10, 2008

  • 83 Answers

SOURCE: Power supply unit, TV cuts off after 20 seconds

i would recommend ebay, they usually have lots of parts for lcd tvs

Posted on Jan 25, 2009

  • 88 Answers


you case a little difficult. you not a technicion. hard to tell me about that connect the cooler fan to tv inside circuit . if you understand that transistor like # kia7812p1.that "s has 1 input . 1 output & 1 ground connection. if take a cooler fan " + "wire connect to that output of transistor & "-- " wire connect to tv dc ground. that " s be cooler fan working when tv on. hopefully could help you. christopher. but that connection i never did it before. good luck!

Posted on Apr 29, 2010

  • 222 Answers

SOURCE: Need a new power supply. Where?

Try E-bay

Posted on Jun 06, 2010

Testimonial: "THanks."

SOURCE: My TV a LG 52LG60 52 in. "Scarlet" HDTV LCD TV

This is a classic switchmode power supply, shutting down to avoid a fire, explosion, or both. This set had developed a problem, that is so severe that the set must be shut down, So the power supply tries to do this, however when it does, the fault, is temporarily removed, (Usually because the faulty component cools down) and then, it restarts up again, senses the fault, and shuts down, and then... and so on...
We call this a "Hicupping Power supply" This set should be removed from the Power, and in my professional recommendation, you should get a "Quote" for repair, from, an, Approved Service Center, this point is very important for a good result, Always contact, their local, "Head Office" Now, when you get the information you want, then you can decide as to repair of replacement. The reason we want an approved agent, is that way, all the engineers are trained on their own brand sets, they have seen almost all faults, and will get the job done quicker, and for less cost, and usually have parts on hand, also sometimes, there has been a service bulletin in issued and the repair may be subsided or even free.
Please find below FYI a Training manuals, this is what I use to teach the technicians to troubleshoot and understand just how it all works and what to do,and how complex and difficult, these units are to service.

Posted on Aug 21, 2010

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