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Thought I would post an update regarding the apparent design flaw in the 50T-701 & 702 chassies which causes the HV to drop off after the set has been playing and gets hot. In my set, I have noticed that the picture will gradually get darker and after about 2 hrs I will notice the picture size bloom slightly, indicating that the HV is dropping off. Although the set is still watchable, I decided to think about preventing the condition from occurring without replacing the entire HV section.
I installed a 3 inch cooling fan to the back cover of the HV cage by drilling a 3" hole in the rear cover and mounting the fan on the cover directly across from the transformer which is apparently the offending component. The fan is so wired that it turns on when you turn on the set and off when you shut it off. After more than two hours, there is no - zippo - visible drop off in HV. There is absolutely no dimming of the picture, or any blooming of the picture, nor any loss of focus or sharpness. The airflow is pushed into the HV cage where it keeps the transformer and other components cool, and then flow up and out through the ventilation holes at the top of the cage, whereupon it reflects off the inside top of the cabinet and back down again so it helps keep all of the chassis top components cool.
The fan i used is a generic 3" (3100rpm) 117 VAC fan I picked up at Radio Shack. The fan is audible, but its not bad nad not annoying or for that matter much noticeable. The big benefit is that the TV is now a nice, reliable steady daily player. This seems to be a very viable solution to a well known problem!
-George-
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04-09-2016, 10:24 PM
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