[Coco] Re: [Color Computer] Ouch!

[Gene Heskett]

On Thursday 18 December 2003 00:47, Rogelio Perea wrote:
>"Neil Morrison" wrote:
>> My all time favorite was told to me by a fellow electrician who...
>
>Ok, a little off CoCo topic but here it goes:
>
>Back in the mid 90s a close friend of mine and myself were working
> at a combo AM & FM transmitter site. Standard procedure dictates
> that the operator must set to ground all potentially hazardous
> contact points within the transmitter using grounding rods located
> in the equipment. Power must be removed completely before
> attempting any "open cabinet" surgery in the transmitters so he
> followed the safety procedures and proceeded to work in the Harris
> FM transmitter. Meanwhile I went back to the other half of the room
> to start working on the AM transmitter; as I leaned over to open my
> toolbox a bright flash illuminated the whole room and a loud POP!
> noise went along... then the smell of burned out metal... as I
> turned around there he was, my friend holding what was left of the
> grounding rod metal (the metal part, the handle was a large solid
> plastic piece) all dazzled and confused, he just kept saying "I
> can't see I can't see". His sight returned soon enough, he was just
> disoriented as when someone flashes a camera at a very close range.
>
>The problem was caused when he touched one of the contact points of
> the filament voltage control rheostat, the control breakers should
> have disconnected if from the 240 VAC line but a design oversight
> prevented that, all the pilot lights were off in the mains AC
> controller so my friend had relied on just disconnecting all the
> breakers built in the equipment, not the mains on the wall
> switch... everything was out of power except that wire in the
> filament circuit.
>
>We did go back to Harris and prompted them on the issue. The HT10FM
> transmitter was brand new in their product line and had some design
> quirks, oddly in that region of the filament circuit - the rheostat
> overheated under normal operation to the extent that the resistive
> elements eroded badly causing a big dent on the control that
> prevented the wiper from moving... that's another story.
>
>The moral was that we learned (luckily with no more harm than that
> temporary flash-dazzle) that ALL power must be removed not matter
> how redundant the procedure might look.
>
>Moving this into the CoCo topic, later that day I was at home and
> designed a full length graphic (letter sized) using CoCo MAX 3. I
> used the basic idea of those old TV ads about drugs -> "this is
> your brain, this is drugs..." putting some notes besides the
> drawings fashioned like:
>
>"This is a grounding rod"
>"And this is a rheostat contact point"...
>
>the sign stood in the transmitter side entrance for a long time.
> Outsiders took a while to grasp the concept :-)
>
>
>-=[ Rogelio ]=-

Great story, Rogelio.

I could relate some of my "Harris" experiences too, most of them 
unflattering to Harris.  The MW-1 comes to mind quickly.
 
-- 
Cheers, Gene
AMD K6-III at 500mhz 320M
Athlon1600XP at 1400mhz  512M
99.22% setiathome rank, not too shabby for a WV hillbilly
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Copyright 2003 by Maurice Eugene Heskett, all rights reserved.