Mystery wire on an Arri 16 S/B power cord. Any Ideas?

[Francis Kuhn]

Hi,

I'm wondering if anyone can tell me what this small coiled wire is. It's at the camera connector end of an Arri 16 S/B power cord. I'm thinking it may be some kind of ground wire, possibly for grounding an AC motor. 

Thanks!

-Fran

[Tim Carroll]

Hey Francis, I'm a bit fuzzy on this but you are correct, that wire is connected to the negative terminal on the power cord. Can't recall what it was used for, but many of the Arriflex 16S power cords had a socket on the back side of the power cord connector, which lined up with the negative terminal, like the one you have pictured.

Best,-Tim

[Francis Kuhn]

Thanks, Tim. I figured if anyone knew anything about the wire it would be you. Hope you're doing good!

-Fran

[Charlie Peich]

Greetings Tim and Fran!

The little wire on the power cord is indeed a grounding wire. It is used to ground the torque motor on the 200ft or 400ft magazines.

Arri literature said: "As the magazine is attached to the camera, electrical contact is automatically made."

Well, yes and possibly no.

In the pic below, the torque motor is attached to the magazine. The torque motor is now grounded to the magazine. When the magazine is attached to the camera body, the magazine is now grounded to the camera body completing the electrical circuit for the little torque motor.

The red arrow points to the contact pin on the magazine for the positive 8 or 12 volts from the camera. The exposed metal of the magazine is supposed to ground the magazine to the camera body....

However, possibly in the early days of the magazines, the electrical ground, for some reason, didn't make a complete circuit through the camera. It could be corrosion that caused resistance in the ground circuit reducing the voltage. Arri backed up this possible (sometimes unpredictable) condition by having a little ground wire that plugged into the small, silver socket (see above pic) underneath the motor and then to the neg side of the power cable. This provided a good positive ground for the torque motor.

When I 1st started shooting with the 16s and mags, I always used the wire. But after a while I stopped that annoyance and just mounted the mag. I never had any problems. The little grounding wire I used finally disappeared (I do have one left .... just in case).

You just forgot about this Tim! lol

Charlie

 

[Francis Kuhn]

Wow--thanks for the info and taking the time to do all of that work, Charlie! I really appreciate it. 

-Fran

[Tim Carroll]

I certainly did Charlie. Been so long since I even picked up a 16S. Still have a pristine one packed away in the basement. Will have to get it out one of these days, probably needs another overhaul. HA!!!

Hope you're both doing well, Happy Holidays to you and yours.

Best, -Tim

[James Parish]

I am in need of a ARRIFLEX SB power cord. Does anyone have one for sale? Thank You, Jim

[Duncan Brown]

There's a pretty crazily priced one ($350) on ebay right now, with new battery and charger.  If you actually need the battery and charger it's a less awful deal.   It does have the "Make Offer" option so you could always see how low he's willing to go.

Duncan