sci.electronics.repair: Sony KV2780R Shorted HOT replacement
Sony KV2780R Shorted HOT replacement
Source: http://sci.techarchive.net/Archive/sci.electronics.repair/200410/1581.html
From: Marc (dbacks_at_attglobal.net) Date: 10/19/04
Date: 19 Oct 2004 07:26:05 0700
I recently acquired a nonworking Sony KV2780R television manufactured in 1987. I know nothing of the history of this television, but it was one step away from the dump.and is an excellent candidate for educational purposes.(aka FREE!) I pulled the back off, and checked the main fuse, it was ok. I plugged it in, and turned it on. I could hear the "on" circuit come on, but no sound or picture. I then unplugged it and began taking a closer look at the video circuitry. (the audio portion of the circuitry appears to be contained on a separate board, probably modular, and probably used on several different models of televisions) The only "clean" area on the video circuit board was a heatsink/transistor subassembly located just in front of the flyback transformer. The heatsink/transistor subassembly was just sitting there, loose, desoldered from the board. (all three of the transistor leads, as well as the heatsink mountings were desoldered from the board) The transistor (D1497) is shorted out. My guess is this: that a repair technician checked the set, and determined that, at the very least, the HOT was bad, and the overall cost of the repair was too expensive, so the television was not repaired. Here is my question:
sci.electronics.repair: Sony KV2780R Shorted HOT replacement When the HOT is determined to be shorted, is this symptomatic of a larger problem??? Possibly other parts down stream or up stream (so to speak) shorting? Again, any and all help is appreciated, Thanks, Mark