Introduction: LCD On-board Powers Supply Repair.

I turned on my #6 PC today and no monitor. Black! After checking the power cable and VGA cable, still nothing. So what do i do, Well i take it apart of course!  What  i found was all 6 of the power supply caps were no good. Only took a visual inspection to determine the problem due to the tops of the caps were pushed up.
This is an internal power supply LCD. Some Flat screen LCD's have a external power supply with a dc plug that plugs in to the back of the LCD.

This is a TG model made by Sampo, from China.
It was surplus when i got it so i suspect it has quite a few " miles on it " 



I am really sorry about these pictures. They are not good. But its the best i have at the moment.

Step 1: Tools and Safety

Some things you will need:

Soldering Iron
Screw Driver's
Solder

I like to use a solder sucker, but you could get by without one.


Always be safe. Take care. Disconnect the power supply before you start a project!

 

Step 2: Take It Apart

Remove the cables. This model has 5 main screws at the bottom hinge area. The rest of the cover is snap together. When you get the back cover off you will see this tin cover. Remove this cover. Take care as there is several wire connectors that need to be unplugged to get the cover off.
Then you will see two PCB's. The smaller one is the controller board, leave it there it is not the problem. The larger  PCB is the power supply board. Thats the problem, continue to remove this board.

Some LCD's have more boards than others. You will have to look for your model online if you can not determine what board is what. 

Hopefully you can see from my pics the 6 caps with the tops pushed up. Those are the problem.
I replaced all 6 caps. Even if there were only 2 or 3 bad caps i would replace them all. 
Make yourself a map of where everything goes so its it is easy to install them later. 

Step 3: Parts

 This is the parts required for this repair:

1) 470uF 10v
2) 1000uF 10v
2) 1000uF 25v
1) 470 uF 25v

Not very many parts. Caps only.

The parts here are so very cheep here. For these 6 caps i paid less that  $1 US.

Step 4: Assemble

Soldier the new caps in the correct place and orientation, working from the map you made earlier.
Re install the board into the tin cover.
Put cover back on along with all accessories. 
Re assemble plastic back cover and hook up the power and VGA wires.
Then take it out for a test drive. If everything comes on and working great then you have saved yourself  from paying the tech plus a new power supply.

I would say a job well done.

I have also completed this kind of repair on a Pentium 4 motherboard and a video card.

I hope there is something here that may help you and thanks for looking. 

Comments

author
sohailhassan (author)2013-09-13

what should we do when the caps are ok but still no power or u can say that power light blinking if u have a solution for them plz tell

author
WWC (author)sohailhassan2013-09-13

My LCD repair really is limited to only a few things. For that problem i would suggest to Google it.

author
iceng (author)2012-12-03

Gutsy move to tackle a supply like that.. ... Good work :-)

A

author
WWC (author)iceng2012-12-03

Thanks
I am using that monitor right now as a matter of fact.

author
kikiclint (author)2012-03-06

I have a monitor that went out. First thing I replaced the caps. It worked 10 minutes, then the transistors in it went out. Turns out one of the small transformers for running the backlight is shot, and it isn't a part I can find anywhere, so I am out $40 to get a new power supply board. Capacitors are always the first place to look though for problem components though. Thanks for the instructable.

I think there is a forum called badcaps which has a lot of info for troubleshooting the guts of electronics like this.

author
WWC (author)kikiclint2012-03-06

Sorry your repair didnt work out. For me if i dont see the tops of the caps pushed up then i generally dont replace them.

Thanks for the site info.

author
WWC (author)2012-02-28

Thank You very much.
As i look back now i think some of my electronic stuff as well as other people i know have been replaced because of this type of failure. If we only knew then .....

author
AndyGadget (author)2012-02-28

Well done on that.
Electrolytic capacitor failure is probably the most common cause of equipment failure once they're over a few years old.  At work, I've had over 30% of a certain model of Lenovo PC fail due to leaking capacitors on the system board.  A fair few went within the 3 year warranty - After that, I started replacing them myself.
Failure to boot and random blue screens are good indicators of this type of problem.

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Bio: Why would i buy something ready made when i can make it myself with half the features for twice the money? DIY!
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