This guide was written using my 32" LCD HD flat TV with DVD player model: 32MD251D/37, however I had repaired this same problem on a monitor and another TV. The problem is 90% always the same; burned out capacitors on the power board.
Causes of a burned out capacitor
Leaving device on for extended period of time
Running the device out of an unstable or damaged outlet
A burned out /bad capacitor can be identified by looking for defects stated below
Asymmetrical or stretched plastic jacket
Symptoms of defective capacitors may include:
Excessive noise in audio or video, including 60hz audio hum or rolling bars in video
Scratchy, distorted, or missing audio
Low contrast, blurry, or distorted LCD displays
Intermittent or outright failure
• Soldering Iron with solder
• Phillips Head screwdrivers
• Flathead screwdrivers
• Sharpie Marker
• (2) Vented axial 1200uF 35v Capacitors - Varies on model/brand of TV
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Step 1: Removing the Backing and H/W Cover
I have opened many flat screen TV's and monitors and they are all pretty much built the same; outer plastic shell, Circuit board cover, a power and control board and finally LOTS of screws :)
So remove all of the backing screws there should be around 8 and the IN/OUT bracke
Remove the 8 (could be more or less) screw in back of TV and set aside
With a thin but sturdy device (a Flathead works) split the two parts starting in the corners.
It takes some small fingers and strength to work of each "pop" joint and prevent "popped" joints from reconnecting
Before removing any screws disconnect any connections to the power board.
Take photos along the project so you know where everything goes and be sure to have all the connection panel screws removed
Now you will be looking at the circuit board cover (shown in image 4-5), go ahead and remove it
Step 2: Replacing the Damaged Components
After identifying the problem, in this case two blown capacitors we will need to remove the old and put in the new.
Unsolder the capacitors one at a time being careful not to cross traces; if you have solder sucker or solder rope then use it.
Once you have extracted the first capacitor, insert the new one and be sure to line up + to +.
Repeat for any other damaged components.
Step 3: Testing and Reassembly
Place the circuit board back onto its backing and secure it with 2-4 screws
Plug in power cable and TV should light up as if it was brand new; if this happens then Congratulations on your success :)
Once your satisfied go ahead and replace all the inner and outer screws and connections
Pop the back piece on and you are finished