Sharp Aquos LC-37LE320E no back light?

[kc8adu]

Re: Sharp Aquos LC-37LE320E no back light?

i just blob both sides well with solder and lift it off once hot.
alternate sides till it lifts easily.place new part and tack down.can also blob it again and wick away excess.

[Dang]

Re: Sharp Aquos LC-37LE320E no back light?

So with a little messing around and doing this, that and the other, a Schottky Barrier Rectifier has blown, showing short across all pins and found at position D985, so the offending part number is: MBRF10100CT, rated to 10amps, 100v, so I ask, would a FCH20U10 be a compatible replacement or is there more to it than I've said? yet again rated at 100v but this time has a peak current capability of 20amps, it's what I have at hand right now, thanks again, Andy.

[Dang]

Re: Sharp Aquos LC-37LE320E no back light?

OK, I have this: FMEN-210A, seems a better match so I shall use this, fingers crossed.

[Dang]

Re: Sharp Aquos LC-37LE320E no back light?

So after all that it turns out to be just this component that was at fault, I measured it to be fine six or so weeks ago but after I tried the hair dryer on it to try and get some life, it just blew completely, well at least on one side, this caused a voltage pull down and so needed replacing. I reclaimed one of these from a long dead Samsung power supply, the one mentioned above and now she's working just fine, been a couple of hours without hiccup so I thank you, especially tom66, was a good learning experience and a good test of patience.

[tom66]

Re: Sharp Aquos LC-37LE320E no back light?

Nice one, in the end.
BTW, if you had used a scope, you'd find the fault very quickly by checking the SWITCH node and the GATE node of the FET:
- no GATE drive - bad IC
- GATE present but no switch spikes - bad diode or FET

[Dang]

Re: Sharp Aquos LC-37LE320E no back light?

For me it showed that components needed to be removed to get a proper reading, with it in place it showed short across all pins, good before the hair dryer, with it out one side was good. Glad I never tried changing that chip, to be honest glad it completely blew or I would of tried changing that chip by now, anyway all is good so thanks again, you were a big help, Andy.

[tom66]

Re: Sharp Aquos LC-37LE320E no back light?

I've changed a few of those ICs. It's really hard to screw it up. Just flood each side with solder, alternate the iron between sides every few seconds, and lift it up using a pair of tweezers.

[Dang]

Re: Sharp Aquos LC-37LE320E no back light?

The lifting part is the easy part, it's soldering one back in it's place that's the hard part, I have tried and practiced, even did the infamous AS15-F but it is hard, trying not to damage the pads, cleaning the pads, making sure it's centred properly, no bent pins etc etc, obviously the smaller the pin pitch, the harder it is but I'd rather not do it if I can avoid it, hot air and solder paste seems easiest for me.

[tom66]

Re: Sharp Aquos LC-37LE320E no back light?

It's more of a matter of steady hands. Just tack one lead once aligned, then do the rest properly, and then go back and correct that lead. 2.54mm/0.1" spacing is not too hard. Wait till you get to 0.4mm/0.15" spacing. That's a challenge to do by hand.