Nov 5, 2017, 11:22 PM
Post #1 of 2
I have a Sumsung LM46D630M3F that squeals and cycles on and off after about a 1/2 hour.
Green mode switch problem?
I tracked down the component responsible for the power cycling. It is a Fairchild green mode switch GM0465R. It runs hot. If I lay an extra heatsink on top of the existing heat sink (TV is face down with back off) it will stay on. It doesn't take long (15 seconds maybe) for the component to cool enough for it to automatically turn the TV back on. I can get it to come back on a little quicker by spraying a duster at it (tipped far enough to get cold liquid out). More telling is that if I take the mounting screw out and pry the switch away from its heat sink it will turn off in less than a minute (starting with a cold TV).
This green mode switch is a T220 package and the factory (Samsung) piles caulk around the front of it. There is more caulk there than anywhere else on the power supply board. I believe caulk is used to keep things from moving which might be a tip-off that this switch is a potential noisemaker.
I'm sure if I bolt on a big enough aluminum plate to the existing heatsink I can fix the power cycling problem. Is it possible that the switch is damaged internally and that replacing it could solve the high frequency audible noise problem? (Or do I just need to pile on more caulk! )