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05-03-2022, 06:05 AM
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#1 |
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Badcaps Veteran
Join Date: Apr 2011
Posts: 226
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42LM670TZA , picture freezing , then powers off , or hanging on LG logo .
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 . |
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05-03-2022, 06:31 AM
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#2 |
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Badcaps Veteran
Join Date: Nov 2013
City & State: ST
My Country: Brasil
Line Voltage: 220V 60Hz
I'm a: Student Tech
Posts: 365
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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. |
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05-03-2022, 07:28 AM
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#3 |
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Badcaps Veteran
Join Date: Apr 2011
Posts: 226
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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 |
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05-03-2022, 08:32 AM
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#4 |
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Badcaps Veteran
Join Date: Apr 2011
Posts: 226
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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 . |
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05-03-2022, 10:04 AM
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#5 |
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Badcaps Veteran
Join Date: Apr 2011
Posts: 226
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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 .
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05-03-2022, 11:19 AM
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#6 |
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Badcaps Veteran
Join Date: Apr 2011
Posts: 226
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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 . |
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05-03-2022, 12:02 PM
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#7 |
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Badcaps Veteran
Join Date: Nov 2013
City & State: ST
My Country: Brasil
Line Voltage: 220V 60Hz
I'm a: Student Tech
Posts: 365
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Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .
Nice job on the reballing process, hope it fixes it.
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05-03-2022, 12:26 PM
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#8 |
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Badcaps Veteran
Join Date: Apr 2011
Posts: 226
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Re: 42LM670TZA , picture freezing , then powers off , or hanging on LG logo .
Thanks again
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05-03-2022, 03:46 PM
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#9 |
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Badcaps Veteran
Join Date: Oct 2016
City & State: Bakersfield ca.
My Country: usa
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 2,732
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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.
__________________
I assume no responsibility for any stupid suggestions I might post. |
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05-04-2022, 02:17 AM
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#10 |
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Badcaps Veteran
Join Date: Apr 2011
Posts: 226
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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 . |
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05-04-2022, 11:27 AM
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#11 |
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Badcaps Veteran
Join Date: Oct 2016
City & State: Bakersfield ca.
My Country: usa
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 2,732
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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.
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05-05-2022, 02:50 AM
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#12 |
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Badcaps Veteran
Join Date: Apr 2011
Posts: 226
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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  |
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