lg47lm620 half a picture

[wreksta]

hi all me again ive investigated the problem from an earlier thread I have managed to get some life and partially diagnose this set

I stripped panel and came across this on the top buffer board which gives no picture

the other side produces a beautiful picture


so cleaned all up and saw that this on the left the copper pad had a blow caused by a shorted smd capacitor I think your opinions are welcome



now what I need to know is hopefully the values and the correct way to test all these smds in the picture

I think this set will live I mentioned the shorted smd cap on buffer cant I just take this out of circuit and hope for the best for a test but replace if it works for a permanent fix
???

[tom66]

Re: lg47lm620 half a picture

The capacitor is there for a reason, you probably can't take it out and hope for the best. The damage looks like water damage, it's often not repairable. Tabs on the bottom of the panel, right?

What you can do is look at other tab drivers, remove the matching cap, test it out of circuit and see what it reads. Then replace both.

[wreksta]

Re: lg47lm620 half a picture

Tom what would cause the blow on that copper jumper

Also can I not just test same smds on working buffer for values
but leave them in circuit mate

[tom66]

Re: lg47lm620 half a picture

Water. Especially if the tabs are on the bottom. These new LED TV put the tabs on the bottom, to keep them cooler and minimise tab bond issues (it works a little, but the occasional tab bond still fails. Theory is heat rises, they're trying to avoid heat produced by the LED backlight from heating up the tabs.) If anybody uses even a little too much water on the screen when cleaning it, the panel can be permanently damaged. Even worse if someone spills their drink on the TV.

You probably can't test them in circuit, because of the other components. But if you're afraid of losing it, you could always lift only one end, and test across there. Because one end is lifted, the component is effectively disconnected from the circuit as there is no path for the current to go.

[wreksta]

Re: lg47lm620 half a picture

tom I bit the bullet and went for it heated the 2 bad resistors lifted them off and replaced them like for like

was only way I could do it but she lives

so im happy keeping this one for myself paid £80 for both 47lm46 series tv not bad