I didn't notice this earlier:


Eutectic.

Normal old solder is lead and tin mixed together. A common ratio is 60% tin, 40% lead. (I don't know what the ratios or ingredients are for lead-free solder.)

The melting point of a mixture of tin and lead (and, for that matter, water and alcohol and other mixtures) changes as the ratio changes. At least for metals, there is a ratio where the melting point is the lowest possible point. This is called the eutectic point.

All temps below are Fahrenheit:
Tin melts at 449.5°
Lead melts at 621.5°
60/40 solder melts 370°
Eutectic solder, 63/37, melts at 361°

Well it's officially toast again. I'm going to try cooking it again and see if it works again. It didn't last a year Brad.(Dec 8-Aug 14?) but what the hell. Football season is almost upon us. For the record I don't use that tv that much. Mostly football Sundays in the fall and for movies. It's in the basement so it doesn't get daily use.

Just put it back together and it's working again. Idk what to tell ya Brad Humphreys

You already did tell me, that it got it working yet again lol

I'm fascinated that this is actually working and so far, has not resulted in any additional damage to components on the board. I am curious as to why it acted up again thou; as the 're-flowing' of solder should have been a permanent fix. Makes me think you might have some other issues now.
But as long as it keeps going :)

Although if you find yourself having to bake your TV boards every 6 months or so, might want to look at finally replacing that TV.

I'll spend the $250 on a new board before I drop another $5G on the TV. Lol

Something to be aware of. There could be a problem on one of the drive boards that is causing to much current to be drawn from the main board. This in turn is causing an IC to 'de-solder' itself.

I'm reminded of Sony RPTV from 12-15 years ago, that if to much convergence was used on the convergence IC, that it would eventually de-solder itself (the massive heatsink wasn't enough to stop this from happening). There was a kit you could buy, with new bias resistors and IC to fix the TV. Kit was like $15 and about an hour of work.

Oh the good ole days when stuff could still be repaired.

Consider the possibility that there is a conductive hygroscopic residue left over from the production line. The "cooking" cycle might drive out the water. If this is the case, a clean water flush and dry will be a permanent fix. (remove any backup batteries before flushing).

As Brad noted, certain devices run so hot they desolder themselves. Not that the solder disappears, but the repeated heat/cool cycles from power on to power off cause them to crack and finally fail. Resoldering fixes. Sometimes the old solder has to be fully removed.

You would normally use a bright light and a magnifier to look closely at solder joints on larger, hotter running devices. Could be a transistor or IC, occasionally a larger power resistor.

I suspect that the cracking solder joints were defective on the production line due to surface contamination. The contaminated solder connections fatigue easily due to temperature cycles and age. Usually, I have trouble repairing these joints until I remove the original, contaminated solder and clean the area. Nearby joints that have not cracked usually don't look to be in good shape.