OT: tvs and fires - article

When I started working on electronics I was not aware of some of the safety procedures. I owned a 20 inch Sharp TV that had a problem somewhere in the MTS Decoder. Stero would not lock in. I connected my scope ground to a ground on the board and turned on the TV. Fire!!! The TV was toast. Power supply, tuner, microprocessor, dozens of traces, exploding caps, frying resistors, etc. I wasn't hurt, didn't burn down the house, and learned some lessons about isolation. But a TV in Standby? I'm sure it's possible, however not likely. There are live parts in the SMPS and a malfunction might even turn on the TV making the rest of the TV live. Or maybe a cat stepped on the remote turning it on (my cat does this sometimes).

What I find hard to believe is this whole thing, based on isolated incidents. A huge percentage of all homes in North America at any given time have one or more TV's in standby mode...how many fires are we expecting?

Tom

Hi Tom...

What floors me is how incredibly lazy we've somehow become. :)

Apparently we can't once or twice a day walk all the way to the set and turn on a power button. Too far, too hard. Can't go any further than the remote. Or maybe can't wait the extra one or two seconds :)

What ever happened to the olden days "holiday" switch?

And has anyone considered the tremendous energy waste of millions of sets each needlessly burning up 10 or 20 watts?

Take care.

Ken

Yes. "Energy Star" rewards companies for making lower wattage electronics. It seems that evrything I own now says Energy Star which should indicate that I'm saving energy. Surely, If I had the same number and type of devices in my home TURNED ON 15 years ago, they'd probably use two or three times as much electricity. However, I might take the time to measure how much wattage is being used in my home on any given day when all of my electronics are "off" but in Standby. Lets see.....

4 Computer monitors - 2 LCD and 2 CRT always with an orange or flashing LED just waiting for a signal to fully power up 2 Computers, printer, router, DSL modem 3 Cordless phones Ceiling fan (remote controlled) 3 TVs and 2 Video monitors Microwave and Stove (with electronic controls) 2 DVD players, 2 VCRs, 2 cable boxes Home theater receiver and 5.1 speaker system with subwoofer that's always waiting for a signal so it can fully "power up" Garage door opener that's always waiting for a remote signal. Laptop computer. About 10 plug-in light sensing night lights ...and that's just the ones I can think of right now. I'd bet it's more than a 100 watt lightbulb for sure. I may start turning off my computers' power strips when they're not being used

A major culprit are the class II transformers used in most of those things and most wall warts. Rather than using a thermal fuse, they wind them with a high impedance primary so they won't overheat if they short, but as a side effect they're only a pathetic 50% efficient and in most cases they're powered 24/7.

The vast majority of TVs in the US have no way to turn of standby short of unplugging the set. Andy Cuffe

snipped-for-privacy@psu.edu

There is that too, of course...

My TV is an older Thomson TX, with no remote capability. I switch channels with my DVD/VCR, but the TV requires manual turn-on. Ideally, if there was a battery (like in a PC) to hold settings, we wouldn't need standby (who cares if the set takes a minute to warm up?). Sometimes we continue to do things while failing to remember why we are doing them...

Tom

Yes. It's a LOT of energy.

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Granted the old "instant on" tube sets used a comparatively large amount of power in standby, but has anyone measured the the standby draw of a modern set? Now I may just have to do that, I suspect it takes very little power to keep the microcontroller running, obviously some use a better design than others though.