42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

[zen]

Hi all

Issue seems to be slightly tap sensitive , although that might be a complete coincidence .

Main board problem none the less .

Can anyone advise .

I'm leaning toward re-balling the main BGA processor chip .

Have the correct stencil in stock , therefore must have re-balled one of these chips in the distant past .

[Biruslapio]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

All signs point to BGA, I have one of these boards from a 42LM6400, after reflowing the main chip it lasted for 2 years, then further reflow attempts failed to make the TV last even 1 minute powered on.

But the TV should not freeze, it should power off immediately or not even get out of standby when it's the main chip.

[zen]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

Thanks for the input .

I don't tend to re - flow any more , as it doesn't seem to be reliable .

Will re - ball & report back

[zen]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

On removal & inspection of BGA , may have worked out issue .

part of track , which looks to be a through hole point seems to have been exposed , by heat from the a capacitor that sits directly under it .

Could try some solder mask to insulate point then fit chip back .

Although it looks like it from picture it's not a pad .

[zen]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

Re-ball seems to have gone really well , & solder mask to took exposed track .

[zen]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

Well i'm genuinely surprised .

Set powers & now working on a test .

Lets see how it behaves , or not a the case may be .

[Biruslapio]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

Nice job on the reballing process, hope it fixes it.

[zen]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

Thanks again

[dskall]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

Reballed a Vizio a couple years ago. Still working in the living room.

[zen]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

Nice one, yes re-balling rather than re-flowing seems to be the way to go for me .

Have been experimenting for a few years now & have quite a reliable technique with the equipment i use .

Many re-balling videos on You Tube .

[dskall]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

I think leaded solder is superior to the brittle unleaded. Military still uses leaded solder for reliability.

[zen]

Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .

Most definitely .

Aviation also , & quite possibly medical equipment .

More work for us i suppose