Epic-M shorting out

[Mike Mastre]

I had a strange situation of the Epic shorting out on a shoot recently and wanted to see if anyone else had ever had a similar experience.

The camera setup:
Epic-M
AB Dionic HC through Matrix plate
AJA HD10DA 1x6
Preston MDR2 running focus only
SmallHD DP6 monitor
(AJA, Preston, DP6 all powered through D-tap quad split from Matrix plate)
Epic sync cable going to the MRD2 run cable

The first time I noticed an issue was after the first setup. Everything was handheld so the camera had a fair amount of movement and jostling around. Got the camera off the op's shoulder and everything was off. Dionic HC still had 3 hr. display on it. Metered the battery and it read about 4 volts. Put a new HC on and everything seemed fine. Next setup more of the same. While setting up the next shot the camera kept shorting out and everything would turn off. Unplugged everything and started over. Everything came back up. Did it a few more times then the DP6 and Preston wouldn't power up. (Finally blew a fuse in the Matrix plate). Went to a second battery to run the accessories to get through the shot. During this time is when I noticed a few things. At one time, without doing anything but moving the camera side to side, the sync cable run bnc that was connected to the preston run cable came in contact with the right angle motor cable in the MDR2. I saw a spark, the DP6 turned off and the camera started recording. On another occasion later while re-routing cables, the other end of a moter cable that was still plugged into the MDR2 came in contact with one of the bnc outputs on the AJA da and the camera shorted out. I was able to get through the shoot by taping over all the connectors, securing the triple bnc sync cable in place and replacing the matrix plate fuse, and the 4 volt reading HCs came back to normal after putting them on the charger. Has anyone had any experience like this, or can tell me what might be going on? Is this just a function of the way power has to be run through a bnc connector to get the camera to run? I have used this same setup before with no issues, but maybe I was just lucky that the sync bnc never came in contact with another connector?
Anyway, be aware that this issue exists. If anyone has a solution other that insulating the sync bncs and other metal connectors, please let me know.

Mike.

 

[ericyoung]

The only way you'll get a spark is if there is a voltage difference between the two bits touching. One of the two parts is positive with respect to the other.

I would expect the outer screen of a camera BNC to normally be at camera chassis potential (nominal ground). However, this isn't always the case, as sometimes a signal ground may be intentionally separate from chassis ground.
Use a continuity meter to check there is very low resistance between bare metal on the chassis and the BNC socket outer shell.

If your meter reads low resistance, then they are connected, and then I would suspect a problem with your MDR2, or more likely the MDR2 cable. Obviously there shouldn't be any voltage on exposed parts of a that cable. Use the continuity meter to check there isn't a short in the MDR2 cable.