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Maxent MX-32x3 HDTV with poor video and a better repair?

Woodman

Dec 3, 2012
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Dec 3, 2012
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The main processor on this HDTV's main board gets quite hot. It has a heatsink but it is small and tends to come off, though mine is still glued on very tightly. Still my TV just started giving me poor a picture (vertical lines, bad color, etc.). Like several other owners of this unit have reported, if you reattach a lose or fallen off heatsink you can get the picture back, though results vary. Because my heaksink is intact, I decided to put a large computer case fan next to my processor and, as predicted, the picture came back to normal. Problem is that picture still goes out sometimes even though I have brightness/contrast at very low settings (if I turn brightness up high then picture craps out). So then I have to turn it off for a few minutes and it is good for awhile again - not a very good fix!

I would like to re-flow the chip for a better repair but noticed that there are lots of surface mounted components quite close to the main chip, not to mention many more directly under the chip. I know this will complicate matters. Will it still be possibly to re-flow the chip, especially regarding the components directly under the chip - won't the small resistors,etc. on the bottom side just fall off when a heat gun is applied from above?

Other info: HDTV is about 10 years old but still makes a good basement TV. Not sure if this caused problem, but the bad picture occurred shortly after I tried to output a 1080i picture on this 760P TV. Others have reported getting this HDTV to output 1080 on the component connectors for viewing text on a computer. For me it did output, but picture was a little "jumpy". Possibly just trying higher resolution partially "melted" a connection on the chip, and bad picture showed up a few days latter when chip got hot enough in melted area(s) causing a bridge/short.


Woody
 
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Woodman

Dec 3, 2012
47
Joined
Dec 3, 2012
Messages
47
pics

Pictures attached. There are about 6 pins in middle left of 2nd picture that are shinier than the rest of them.
 

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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
25,510
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25,510
Those pins look like they were hand-soldered. Perhaps they were not correctly soldered originally and this is the result of a repair. It is possible that the board was like this new, or it may have been the result of an earlier repair.

It is highly unlikely that a difference in a signal could melt solder.
 

Woodman

Dec 3, 2012
47
Joined
Dec 3, 2012
Messages
47
Those pins look like they were hand-soldered. Perhaps they were not correctly soldered originally and this is the result of a repair. It is possible that the board was like this new, or it may have been the result of an earlier repair.

It is highly unlikely that a difference in a signal could melt solder.


Thank you for your professional input. I'm sure you are correct, fault is coincidence, not cause-effect. It is good to know that I did not melt the chip by changing resolutions. TV was purchased new and has work flawlessly until last week. Any advice on repair - re-flow? I figure I will get one shot and would like to do it right, but if repair attempt fails, the control boards are for sale on eBay for about $25. Of course an eBay board could have same problem.
 

Woodman

Dec 3, 2012
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Joined
Dec 3, 2012
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Attached are pictures top and bottom of the main board. Any advice on re-flowing the main processor (chip with green heat-sink) on a dual sided board would be appreciated?

PS I like Electronics Point's green background colors better - was unique.
 

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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
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25,510
What evidence is there that you need to? It appears to be the sort of chip that has the leads coming out of the sides so you can inspect the solder joints. DIY Reflowing of large chips as a repair method is typically reserved for BGA chips that have all of their connections under the chip.
 
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