As a side note Color TV didn't come in until 1955 and everything for awhile was RCA (or an RCA circuit )..... I got a shock from a RCA CTC-12 color TV. My friend, the late Ray Gilliam was teaching me things. I discharged the CRT twice and reached in to remove the HV lead and POW! I saw stars. He said I had not discharged it enough. The CTC-12 is a 1963 RCA chassis.
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Worst Shock Experience
- Thread starter BobOnTheJob
- Start date
About a year ago another engineer I know and often work with was working on a Harris FM3.5 transmitter. The problem was when you hit plate on the relays would click in and no plate voltage or plate current was showing on the meters. We had both been in this transmitter many times and knew it very well. We had seen this problem before many times, open soft start resistors or bad solid state relay or open rectifiers. This transmitter has a big flat washer that is spring loaded and normally is held open when the back is on the transmitter. Take the back off and it shorts the HV to ground. The AC breaker is cut off, the back door is taken off shorting the HV to ground, no bang, the caps were not charged and that agrees with the plate voltage meter. He gets on the floor and leans over into the transmitter looking close at the soft start resistor. As he is looking around he lays an arm across one of the HV caps and quickly sees a flash and the smell of burnt flesh. The problem on this transmitter was the wire coming from the output of the HV supply had burnt into. The HV caps were at full 5KV+ charge. This resulted in a trip to the ER and some nasty burns , It could have been much worse.
Knowing this transmitter as well as I do I probably would have done the same thing.
Moral of this story is no matter how well you know a piece of equipment dont take nothing for granted, He failed to use the Jesus stick as I also often did. Don't forget the basic safety procedures. This has been a wake up call to me. We were both careful to use the stick on equipment we did not know as well but had gotten to slack with safety proceedures on equipment we knew well.
Everyone! Please! USE THE STICK!
Knowing this transmitter as well as I do I probably would have done the same thing.
Moral of this story is no matter how well you know a piece of equipment dont take nothing for granted, He failed to use the Jesus stick as I also often did. Don't forget the basic safety procedures. This has been a wake up call to me. We were both careful to use the stick on equipment we did not know as well but had gotten to slack with safety proceedures on equipment we knew well.
Everyone! Please! USE THE STICK!
KGMN-FM's Harris FM-1K.
Front panel plate current meter is in the high side of the power supply. Some how the metal face plate of the meter came to be one with the terminals. The meter aparently caught fire and blew the window off. Thinking nothing of it I went to put the window back on and suffered a shocking experience to the tune of 3kV at 500mA in my left hand.
Front panel plate current meter is in the high side of the power supply. Some how the metal face plate of the meter came to be one with the terminals. The meter aparently caught fire and blew the window off. Thinking nothing of it I went to put the window back on and suffered a shocking experience to the tune of 3kV at 500mA in my left hand.
About 20 years ago, removing no longer used video cables inside a rack at a TV. From out of nowhere, a huge throw-you-against-the-wall shock! Turned out that some years before someone had removed a rack of tube-type video distribution amplifiers and simply cut off the 250VDC power feed leaving the cut end in the bundle with a bunch of video cables. The power supply was at the top of the rack, still powered up and being used with one last (out of eight) remaining DA chassis.
Or what you say when you try to ground a hot 208/240 200 amp buss that's supposed to be off.Kent T said:
"Crack-BOOM" &^%#$&@% !
OK I'm curious about this whole Jesus Stick thing. I understand why you guys use it, but my question is what exactly is it made of? Just a piece of wood? Maybe an old broomstick? Forgive my ignorance because I have never worked on atransmitter before, let alone had the chance to watch someone else do it. 
R
R
The Jesus stick is in the back of the transmitter. It is about 24" of a composite material in a rod shape, commonly referred to as "masonite" and a non conductor. On the end of this stick there is a hook shaped piece of metal, that is attached to a shielded heavy cable, that is attached to transmitter ground. You use the stick to touch any potentially charged or "live" source, after the power has been disconnected. Sometimes, you will be surprised to find a capacitor "bleeder" resistor has gone open, and you will get a big spark. Better to hear it than to be the discharge path thru your body! Heed the admonition...ALWAYS use the Jesus stick or you.....JBI
jboyd said:
Thanks for explaining it!
R
Powell E. Way III W4OPW said:
Actually, there were some color TV's built before 1955. Emerson, Westinghouse, CBS, Motorola, GE and others made sets. They are quite collectable these days. You might find the Early TV Foundation's web site to be fascinating. http://www.earlytelevision.org/15_inch_color.html
And you could get a hell of a shock from any of them....
A few years ago a friend managed to get a tour of the WLW transmitter site in Ohio. The engineer giving him the tour pointed out where the 500,000 Kw VOA transmitter had been and then pointed down at the floor.
After all these years, the impression of some engineer's rubber crepe soled shoes was still fused into the linoleum floor. He was told that fortunately the man survived.
After all these years, the impression of some engineer's rubber crepe soled shoes was still fused into the linoleum floor. He was told that fortunately the man survived.
My worst shock wasn't a shock, but the blinding flash. I was tightening a RG-62U, ? coax connector in a 300 HP motor drive cabinet, looking for a communication fault at a coax terminator/splitter box. I had turned the 3-phase 480 off, then on, then off,
and had lost track of which state the main was in.......When I swung the end of the crescent wrench on the coax, the swinging end of the wrench glanced off a live 480 line. Blew the 500 amp main breaker up the line.
I was between the 480 and ground on the wrench, had one hand free, and felt nothing unusual, but the flash was...
noteworthy. The guy standing next to me was a bit more surprised than I was.
No parts were damaged, not even on the communication circuit I was working on, but there were flash burns to ground from the coax-splitter block to the back plane.
After work, I went down to the lake and watched the ducks for a while. Had a bit of eyeball sensitivity.
The worst SHOCK I've had was at work, walking past a hopper full of scrap printed material fresh off a press and
full of static electric charges. The hopper was steel and and it was quite full of magazine signatures.
As I approached the end of the press, to walk around to the other side of the delivery area, a bolt shot out of the
steel hopper and hit me right in the tip of my reproductive-and-pleasure equipment.
I jumped pretty high, and doubled over, but did not fall.
Now I make sure I approach such hoppers in such a way that if I'm going to get bit, It's on the hip, not a frontal strike.
and had lost track of which state the main was in.......When I swung the end of the crescent wrench on the coax, the swinging end of the wrench glanced off a live 480 line. Blew the 500 amp main breaker up the line.
I was between the 480 and ground on the wrench, had one hand free, and felt nothing unusual, but the flash was...
noteworthy. The guy standing next to me was a bit more surprised than I was.
No parts were damaged, not even on the communication circuit I was working on, but there were flash burns to ground from the coax-splitter block to the back plane.
After work, I went down to the lake and watched the ducks for a while. Had a bit of eyeball sensitivity.
The worst SHOCK I've had was at work, walking past a hopper full of scrap printed material fresh off a press and
full of static electric charges. The hopper was steel and and it was quite full of magazine signatures.
As I approached the end of the press, to walk around to the other side of the delivery area, a bolt shot out of the
steel hopper and hit me right in the tip of my reproductive-and-pleasure equipment.
I jumped pretty high, and doubled over, but did not fall.
Now I make sure I approach such hoppers in such a way that if I'm going to get bit, It's on the hip, not a frontal strike.
Old PD said:
500,000 kW?
I want a picture of that one--if they made a wide angle lens to capture something that would have have been at least 6 city blocks long. Also, I thought the VOA site, while not a long way from WLW, was in a different location.RadioFan2J3 said:
Google found this:
http://www.rfproof.com/WLW/wlw_500kw_transmitter_mason_ohio.htm
http://www.rfproof.com/WLW/wlw_500kw_transmitter_mason_ohio.htm
One concept that I learned very early in my electronics career was dielectric absorbtion. Don't just discharge that CRT once. Do it several times and then keep a grounded clip lead on the anode cap while removing it. Geez I hate shocks.
That's what I'd always believed Tom...500KW at WLW rather than 500,000KW at the VOA.TomZ said:
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