LCD Flat Panel Displays > How hard is it to replace a power supply?
trdracing5's Avatar trdracing5 09:08 AM 07-17-2009
I have a 37" LG LCD (model 37LC2d) that has been diagnosed as needing a new power supply. The total to fix was quoted as $400. That is way too much for me to put in to a 2 year old LCD TV.

How hard is it to replace the power supply myself?

MrBobb's Avatar MrBobb 11:12 AM 07-17-2009
Don't own a LG and never open on up.

However, everything nowadays is modular in fashion and the PSU should be a plug-in thing, just like in a PC. Have u worked inside a PC? U may need some screwdrivers, a cutter/plier, but I doubt anything more.
Vermifuge's Avatar Vermifuge 11:16 AM 07-17-2009
Quote:
Originally Posted by trdracing5 View Post

I have a 37" LG LCD (model 37LC2d) that has been diagnosed as needing a new power supply. The total to fix was quoted as $400. That is way too much for me to put in to a 2 year old LCD TV.

How hard is it to replace the power supply myself?

The power supply is the one piece of hardware in any electronic device that has the potential to kill you. It's not sealed like in a computer and should only be done by a professional.
hammerdwn's Avatar hammerdwn 04:08 PM 07-17-2009
You don't have to worry about hazardous voltages as long as you unplug the Tv before you start the repair. Yes some components will hold a charge even when not plugged in, but the amount of current (if a discharge does happen) is not anywhere near the amount needed to kill a normal person. Simple rule is do not touch the bottom/back of the board where all the exposed solder points are.

All you need is a screw-gun and some common sense. In many ways it's even easier to work on than a computer.
Vermifuge's Avatar Vermifuge 05:48 PM 07-17-2009
Quote:
Originally Posted by hammerdwn View Post

You don't have to worry about hazardous voltages as long as you unplug the Tv before you start the repair. Yes some components will hold a charge even when not plugged in, but the amount of current (if a discharge does happen) is not anywhere near the amount needed to kill a normal person. Simple rule is do not touch the bottom/back of the board where all the exposed solder points are.

All you need is a screw-gun and some common sense. In many ways it's even easier to work on than a computer.

The capacitors in(on) a power supply can hold a lethal charge up to a year. Don't believe me?

http://electronics.howstuffworks.com....htm/printable

Applications
The difference between a capacitor and a battery is that a capacitor can dump its entire charge in a tiny fraction of a second, where a battery would take minutes to completely discharge. That's why the electronic flash on a camera uses a capacitor -- the battery charges up the flash's capacitor over several seconds, and then the capacitor dumps the full charge into the flash tube almost instantly. This can make a large, charged capacitor extremely dangerous -- flash units and TVs have warnings about opening them up for this reason. They contain big capacitors that can, potentially, kill you with the charge they contain.
Extreme_Boky's Avatar Extreme_Boky 06:09 PM 07-17-2009
Quote:
Originally Posted by trdracing5 View Post

I have a 37" LG LCD (model 37LC2d) that has been diagnosed as needing a new power supply. The total to fix was quoted as $400. That is way too much for me to put in to a 2 year old LCD TV.

How hard is it to replace the power supply myself?

Remove the back plastic cover (2-5 min)
Remove the connectors (probably 3 - 4 connectors; total 20 sec)
Remove the power supply board - usually 4 screws only (1 min)
Install the new power supply board (1 min)
Re-insert connectors (20 sec)
Put the cover back on (2 - 5min)

Total time: 10-15 min.

The capacitors in switched mode power supply do not store lethal charge and will discharge fully almost immediately after you switch the TV off. However, to prevent any possible zaps, hold the power supply PCB at its edges.

Enjoy.

Boky

.... make sure you disconnected the mains (110 / 120 or 220 / 240 V AC) first!
.... power supply replacement at your own risk.
Vermifuge's Avatar Vermifuge 06:14 PM 07-17-2009
Quote:
Originally Posted by Extreme_Boky View Post

Remove the back plastic cover (2-5 min)
Remove the connectors (probably 3 - 4 connectors; total 20 sec)
Remove the power supply board - usually 4 screws only (1 min)
Install the new power supply board (1 min)
Re-insert connectors (20 sec)
Put the cover back on (2 - 5min)

Total time: 10-15 min.

The capacitors in switched mode power supply do not store lethal charge and will discharge fully almost immediately after you switch the TV off. However, to prevent any possible zaps, hold the power supply PCB at its edges.

Enjoy.

Boky

If for any reason the bleeder resisters/circuitry have been damaged trdracing5 could be in for a world of hurt. These newer LCDs have large capacitors in place to help power up the display quickly. That's why you can disable the quick start in some of the newest TVs.

P.S. Thanks for adding ".... power supply replacement at your own risk."
Extreme_Boky's Avatar Extreme_Boky 06:18 PM 07-17-2009
Quote:
Originally Posted by Vermifuge View Post

If for any reason the bleeder resisters/circuitry have been damaged trdracing5 could be in for a world of hurt. These newer LCDs have large capacitors in place to help power up the display quickly. That's why you can disable the quick start in some of the newest TVs.

yes, that is why I suggested to disconnect the mains first

Boky
MrBobb's Avatar MrBobb 09:53 PM 07-17-2009
Quote:
Originally Posted by Vermifuge View Post

The power supply is the one piece of hardware in any electronic device that has the potential to kill you. It's not sealed like in a computer and should only be done by a professional.

Are we being a bit melodramatic here?

Sure the ole CRT had like 15,000 volts and needs to be discharged properly, but modern LCD, what voltage are we talking about?

OK, I agree, don't do it in the bathtub.
Extreme_Boky's Avatar Extreme_Boky 02:18 AM 07-18-2009
The most dangerous is approximately 400V DC used by switched mode power supply as DC bus (if your mains voltage is 240V AC).. This has potential to kill you…
Tuner: +5 and + 15 (and possibly -15) V DC
Pixel driver board: +15 V DC
CCFL driver board +60 and -60 (this is 120V DC…. can give you shock...)
CCFL high tension / high frequency AC can not do much at all.... but to give you very mild local burns ... and a smell of a BBQ...

Of course, all the above is with the TV ON…., so avoid SMPS and Inverter boards….


Boky
hammerdwn's Avatar hammerdwn 09:06 AM 07-18-2009
I've never been zapped from any lcd power supply after the power is off. I have seen arcing, burning, smoke with them plugged in. Stay away from the inverter connectors to the panel when power is applied!

I have been zapped more times than I can count by plasma and crt based boards after they are removed from the Tv. It will make your fingers numb for a few seconds, that's it. I've had some zaps from live circuits and those can run up your arm and into your chest, but never had to seek medical help for it.
gtaylor0's Avatar gtaylor0 01:20 PM 07-19-2009
OMG One has to wonder is this will be your final post.
MrBobb's Avatar MrBobb 11:33 PM 07-19-2009
Hey once u get zapped a few times, u may start liking it.
trdracing5's Avatar trdracing5 10:46 PM 07-26-2009
Im still trying to decide whether I want to do this myself and risk death!!!!
The part itself is around $125.
That means the repairman is making $275.
Does that sound reasonable? It doesn't to me.
How much should this repair actually cost me????
hammerdwn's Avatar hammerdwn 08:04 AM 07-27-2009
Labor is $250-$300 these days
trdracing5's Avatar trdracing5 08:12 PM 08-15-2009
I just couldn't justify paying that much to fix the tv so I purchased the part and fixed it myself. Works fine and was actually pretty easy to do. No problems at all.
Extreme_Boky's Avatar Extreme_Boky 02:02 AM 08-16-2009
Quote:
Originally Posted by trdracing5 View Post

I just couldn't justify paying that much to fix the tv so I purchased the part and fixed it myself. Works fine and was actually pretty easy to do. No problems at all.

Great news!!! Well done !!!

Boky
bill4903485's Avatar bill4903485 08:56 PM 08-17-2009
Just use caution, a little bit of common sense, and you should be fairly fine. Either hold the board on the edges or simply discharge the caps. Part of the scare tactics are those not wanting consumers to hone in on their action. Obviously some of the concern is genuine.
See The Light's Avatar See The Light 06:57 PM 06-14-2012
How to remove the pins ? ? ? ?

I'm attempting to remove the power supply board from my Sanyo DP42040.

The pin to the AC power cord came off easily.

But the pin for the cable, that goes to the circuit board, does not want to come off. There is a "flange" to press, which I do fully press, and then I pull out,,,, but nothing.

The other pin, that goes to the screen?, does not have a "flange". Is there something I need to do, other than just pulling on that pin ? ? ?
MrBobb's Avatar MrBobb 07:10 PM 06-14-2012
Post a close-up pix.
See The Light's Avatar See The Light 04:26 PM 06-17-2012
The tool I found to safely remove the female pin connector from my LCD TV power supply board was from Radio Shack, part # 276-2101.

It was $9.99. It's labeled as a PLCC Square Extractor Set 0-40293-13433-4

http://radioshack.com/product/index.jsp?productId=2062619

The tool looks like this:

300
oil2gas's Avatar oil2gas 07:29 PM 05-08-2014
sir
l also have aLCD42inch Samsung 1080 that needs a power supply??
When I turn the TV on the red led and blue bar that both indicate that power is on and screen will turn on ??? Well now it only chirps but red LED and blue bar turn on but the chirp noise comes on and off like when you turn tv on and off but nothing on screen...
so I am assuming that its my power supply also
Thanks
Sonny
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