Ever seen spark at BNC connections?

[System77 0]

Hi all. First post, but Ive been reading these forums for some time.

 

Maybe someone has some insight into the following issue..

 

Sparking BNC terminations.. I was troubleshooting a 16 camera system the other day that had some cameras flickering on and off, and I got a small but noticeable shock at the harness end of the system while switching channels. I was handling some of the BNC terminations and one of the cams went off for good at that point.

 

I later opened the cam case and found two burnt microchips at the lens end of the board, but not until later in the day as I my initial reaction to a camera going down was a bad termination or line.

 

As I was testing the lines and channels, another camera went out. This time I stopped and went to the camera to check the termination..

When I unplugged the BNC connector from the camera, I saw a blue spark between the BNC and the connector.. That cam stopped working too..

 

The power source for these cameras seems solid enough and Ive tested it and checked all fuses, but this doesnt seem like a power supply issue as the 'current' appears to be within the coax..

 

Note: the two cams are in completely different areas of the building and run their own power lines/coax, as far as I can tell its all been done properly (by the previous owner years before )

 

Note: A few cams at the harness end would blink on and off unpredictatably when the outer sleeves of the BNC terminations came into contact with each other indicating a ground issue...

 

Note: there are two 8 channel harnesses running into a DVR card on an older PC..

 

The only source I can think of that would be capable of sending an electrical surge throught the Coax is the DVR Card, or possibly very faulty harness connectors shorting out the system.. but Im suspect as the harness system shouldn't be sending out a signal, but rather designed to receive a video signal.. of course I realize one of the pins is a ground and there is a small amount of voltage at the pin end of the plug but its a grey area to me..

 

or is it possible that the current is coming from the camera end somehow? They are both the same camera, Sony CCD in an Eversonic case..

 

has anyone ever experienced anything like this or have any insight into such an issue?

[VST_Man 1]

potiental can be "induced" anywhere on the cable from any electrical source.........

 

if you can get a metered reading use that as your starting point and then disconnect things one at a time........until it disappears. then follow that until it makes sense.

 

Yes, the card can also do it.

 

And, is this connected onto anything like satellite cabes or telephone lines?