Samsung LE40M87BD 40" LCD TV Turns on then picture goes

[MancMan]

Hi I have a Samsung LE40M87BD 40" LCD TV which is fine for a while switches on then picture disappears ????

I have taken the back off and look for the common capacitor bulging issue on the PSU but they all look fine .... I'm at a bit of a loss now with only a visual inspection and think it may be time to get testing the circuit board components individually .... Any idea / suggestions would be much appreciated

 

[ChrisFrost]

If this is a fault that develops after the set has been on for a while then heat may be a factor. Transistors fail once they reach a certain temperature. A quick diagnosis tool is a can of freeze spray. (Google the term from Farnell's or Maplin). A little blast on a suspect component will help you identify a rogue transistor.

Of course this isn't the only possible cause. There could be dry joints or other issues.

As always, electrical safety is paramount and any decision to proceed is at your own risk. If in doubt then take your product to a qualified service engineer... blah blah blah.

 

[MancMan]

Thanks Chris, I will give that a try. From a second look it does look like this TV has already had a few replacement capacitors but it doen't look to have been done to a great standard so I will have another look at that.

Also I have noted on the main board that one of the low level capacitors has a small amount of orange goo on the top. I will take some pics before and after I have attempted the fix .

 

[Sam Gangee]

I'm with Chris on this. Whilst it may be a faulty capacitor, the faulty ones tend to show up when cold, while semiconductors tend to fail when hot. Bad joints can show up at any temperature.