James Emory
February 27th, 2005, 02:04 PM
I experienced a terrible thing a couple of days ago. I was in one of those fancy touring coaches (buses) with my XL-1 hooked up to a big screen playing back some footage. I thought the picture looked washed out on the big screen so I decided to connect the camera to my 9" field monitor. I disconnected video only from the camera and left the audio from the camera connected to the big screen. I then attempted to connect my field monitor into the camera video out for a better picture. As I touched the cable tip to the video out of the camera a spark flashed and then there was this smell of burned plastic. Well, I thought that was it for the camera. Amazingly, the camera works fine recording an image and sound from the camera mic. However, we later found that when we tried to hook up a field mixer to the XLR adapter (MA-200) the right channel was gone, only white noise. I knew the video out was burned out but how could that have affected audio and then only one channel? Does anyone have any idea how this could have happened in the first place? Should it matter if you are outputting audio and video to different sources? How much damage could have been done even though the camera works fine other than the video output and the right audio channel failing when using the XLR adapter? The big screen and 9" monitor were plugged into different outlets on the bus and someone there mentioned that possibly a difference in polarity of the two outlets may have been the reason. Any ideas?
Chris Hurd
February 27th, 2005, 04:10 PM
Man, I think the only thing that really matters is that you get your camera in to Canon factory service and let them fix it. Sounds like it could have been a lot worse,
Jack Smith
February 27th, 2005, 08:39 PM
Although we don't always follow the rules , we're suppose to power off gear before making or breaking connections.
You didn't say but just as a word of warning to others.Especially in a vehicle moving down the road.
In a vehicle there is a lot of potential for a static charge to build .
Slide out of your seat and touch the metal door post and under the right conditions you get a zap.
Static charge can be very high voltage and could easily jump internally .That may have contributed.Also there really isn't any true --- ground--- as the vehicle is on rubber tires.
I agree with Chris and hopefully you don't have too much of a repair.
James Emory
February 28th, 2005, 10:10 AM
Yes, I agree with that protocol but when you get away with not doing it with no incidents a few hundred times you know how that goes. I initially thought of static shock but don't remember rubbing my feet across the floor or anything else to cause it. The actual spark was much bigger than a typical static discharge and the pop was really loud. My fingers were right on the BNC as I touched it to the video input on the camera and I didn't feel anything when it flashed and popped. There was no damage to the 9" monitor either. Why couldn't it have been the other way around?
Ben Simpson
April 20th, 2005, 04:44 PM
I have had a problem with something like that before. It was the connection wire inside of the MA-100 in this case and I just opened up the wire and the wire was not connected so I just soldered it back in.
Frank Daghigh
April 26th, 2005, 11:19 AM
Here are some answers to your questions. This has happened to me a few times installing / fixing car stereos. The reply is inter-twined with your original email text:
"I experienced a terrible thing a couple of days ago. I was in one of those fancy touring coaches (buses) with my XL-1 hooked up to a big screen playing back some footage. I thought the picture looked washed out on the big screen so I decided to connect the camera to my 9" field monitor. I disconnected video only from the camera and left the audio from the camera connected to the big screen. I then attempted to connect my field monitor into the camera video out for a better picture. As I touched the cable tip to the video out of the camera a spark flashed and then there was this smell of burned plastic. Well, I thought that was it for the camera. Amazingly, the camera works fine recording an image and sound from the camera mic. However, we later found that when we tried to hook up a field mixer to the XLR adapter (MA-200) the right channel was gone, only white noise. I knew the video out was burned out but how could that have affected audio and then only one channel? Does anyone have any idea how this could have happened in the first place?
The voltage available in a car/bus can vary from 10v to 18volts. The negative terminal of anything hooked up to the alternator / car battery is never a true Zero volts (Ground). This Voltage could be floating depending on how much load is on the circuit (ie. - number of lights on / heater /etc.). While you had the audio hooked up (which has its own ground) to the bus's Audio, you hooked up the camera's Video connection to your field monitor to a different source of energy at a much different ground level. This difference in ground voltage plus the ESD (Static Electricity in your body) have ganged up on you to create the bang. Keep in mind that the Shield (case) of the RCA (A/V) jacks are in fact the ground connection.
Should it matter if you are outputting audio and video to different sources?
Although following the golden rule of equipment shutdown prior to interchanging wires/cables should always be the case, it shouldn't matter if you are at home and are using the same AC source for all of your equipment. This way they all use the same ground connection which in turn is tied together at you home's / studios' Circuit Breaker box.
How much damage could have been done even though the camera works fine other than the video output and the right audio channel failing when using the XLR adapter?
You are certainly lucky!!! You have most likely blown the amplifier / Driver that conditions your A/V RCA jacks. This amplifier / Driver most likely took the big hit first and acted as a fuse. However, nowadays not too many service centers change a device like that and most likely will end up changing the entire PC board.
The big screen and 9" monitor were plugged into different outlets on the bus and someone there mentioned that possibly a difference in polarity of the two outlets may have been the reason. Any ideas?
See the above please.
I hope this helped. We all get caught up in freaky accidents like this. But the good news is that once it happens to us and end up paying for fixing it, we will always remember not to make the same mistake again. At least that has been my experience!!
Good luck,
Frank