Safety and the Old Guys

Just read an article about tech management dusting off the old skills - getting back into the troubleshooting business. Used to be (ah, the good old days) everything was troubleshot to the component level. Little hard to do now..."I'll change the 9th fet on that array of 12 switches"...but, nonetheless, there're a lot of problems that can be fixed on the bench instead of sending the box back to the manufacturer or ordering a whole new card. And the time is definitely right for anyone with those skills to assert them. A half hour working through that ARC-16 can save a $900 round trip for the unit. Couple that with the pressure to cut costs, and it makes bench servicing that much more attractive. For anyone who's been content sitting at a desk, or even in the field but managing others, hauling out the VOM and scope brings with it safety concerns - ones we all observed as second nature in those component days. Here're some thoughts on safety. Disclaimer: I'm not a lawyer. I don't play one on TV. However, safety around electronic gear can get pretty complicated. I don't pretend to have all the bases covered here. Use logic! That said, these are some points we all need to remember. Yeah, some of the comments are tongue-in-cheek but it's only to make the rest of it stick. Dress the Part: What? Not the greenie...just remember to take off the watch, rings and all the gold chains. But it's low voltage only. Try this: make a "wedding ring" out of a piece of number 12 copper and lay it across a good sized 12 volt battery. As it's glowing, imagine your finger inside. Gloves...good enough for the Lone Ranger, good enough for me...especially the hand holding a probe. Shoes...something in a brown slip-on? Try a pair that provides some electrical insulation. I've heard that you can increase your body resistance by wearing a striped shirt - grey-white-green. Light up your Life: Play a little Debby Boone - or put some light on what you're doing. I know I've moved from working in the shadows to needing at least one light on the work, and a bright one, too! "I want every available light dumped out on that runway" - Lloyd Bridges, Airplane You Gotta Have Friends: Working alone isn't a good idea - even the low voltage jobs. Dead Circuits: If at all possible, only work on dead circuits. Takes a little longer to turn the power off, connect a clip lead, power up, read the meter and power back down, but it's a lot safer than probing a hot board. A) less of a chance of getting fried and B) no accidentally shorted traces that cause a transistor to blow in order to protect the fuse. When Ground isn't a Good Thing: When you're the low-Z load. Working on a cement floor or a damp one, or a metal workbench where you can make contact with it - all invite a little extra current that, frankly, no heart needs. When Ground shows up Uninvited: Most test gear is unbalanced (probably since most engineers are, too). That ground lead you're clipping somewhere could, under some circumstances, make the chassis of the test gear hot. Test this by grabbing a hot dog with a fuse puller and holding it between the chassis of the test gear and ground. If it starts to smell like you're grilling out, double check the gear. The One Hand Rule: Keep one hand in your pocket and only use one hand if you have to probe a live board or circuit. Short it Again: Check that filter cap (or other storage devices) - then short it - a second time - (leave it shorted if you can or at least check with a meter) before prowling around in a circuit. Don't Reach: If you can't see it, you can't really test it - and you don't know what charge that whatever-it-is is carrying. and Don't Point: OK. Seems silly, "Don't point." But you can draw an arc from an energized circuit. Once, again, even if you're 50+j0 ohms, you don't want to be the load. It's happened. and, if you're Tired: Don't be a hero. Pack it in. Nothing better than bopping in at 10 after working till 4 to get a piece of gear working and seeing all the smiles on the folks actually using it. But it's a heckuva lot easier to make mistakes at 4 than at 1. When that 5 mic capacitor you put in fails because you couldn't see that the original was 50 volts and not 35, your fans suddenly act like they're at a Phillies game and down 7 runs. Len Watson Scope+Focus, Inc. scopefocus.com