Melting Ronin Rig?

Daniel Lewis · May 14, 2016

I'd appreciate any insight into this mind-boggling issue I had while working on pre-production last week.

I was working as Assistant Camera and preparing a rig for the DP, the kit was as follows: Sony A7s, DJI Ronin, Redrock Follow Focus, Atmos Ninja, Radian Pro Transmitter/Receiver. We ran a dummy battery from the Sony and plugged that into 1 of 2 PTAP connections that are built into the Ronin. The other PTAP was used to power the Redrock. Our USB connection was powering the Radians and both the transmitter and receiver were powered by the included USB to included battery packs. Lightweight setup, everything was working fine during calibration...

When we powered on the Ronin, both the PTAP connection in the front AND battery unit for the gimbal started smoking. We had a technician on hand, and we quickly powered the solution down and started searching for the source of the extra heat. We had bongo ties that were holding our transmitter to the very bottom of the Ronin (where the battery is). Thinking that plastic from the ties were the issue, I placed velcro onto the bottom of the Ronin instead, and changed one of the PTAP connections for a lighter, shoestring cable.

Powered the Ronin on a second time, and both the battery and the GMU on the front motor started melting to the baseplate of the unit, like a hot knife through butter. I have a background in electronics and I have never seen a steadicam unit act like this before. Fortunately, none of the equipment is permanently damaged, but we are left scratching our heads as to why this solution didn't work for us. We don't have a crazy amount of voltage running through the system and the Ronin battery was handling just fine when we were fine tuning the motors.

Does anyone have any insight into something I'm missing? Pictures are included of the setup, any help would be appreciated. Thanks all!

Edited May 14, 2016 by Daniel Lewis

Dom Jaeger · May 14, 2016

Sounds like you had a short somewhere, dodgy connector maybe.

Shawn Sagady · May 14, 2016

Short or flipped polarity. Probably fried things on the first connection and then had a hot short on the second.

Daniel Lewis · May 15, 2016

Short or flipped polarity. Probably fried things on the first connection and then had a hot short on the second.

Thanks for the response Shawn...any suggestions on what caused the hot short?

Daniel Lewis · May 15, 2016

Sounds like you had a short somewhere, dodgy connector maybe.

Thanks for the response Dom...we swapped both PTAP connectors out twice, you think it was an issue with the connectors on the Ronin?

Dom Jaeger · May 15, 2016

I'd need to see the setup to properly understand what's going where and what melted, but if you have some electrical understanding and a multimeter you should be able to trace out the circuit and work out where the current was being shorted back to the battery. Could be a connector, could be a socket where a wire inside has come loose and is shorting, could be a reversed polarity connection.

It might be best to take all the components to a rental house technician who should be able to diagnose the fault fairly quickly, otherwise it might happen again.