ARRI Forum

Hello
Today i had a problem with Rec function on Alexa Mini + WCU-4 + UMC-4 + 3c Cforce motors combo.
When i hit Rec button on WCU-4, camera started to Rec but it stops after a second.

I had to configure a user button on WCU-4 to start / stop camera rec and it this way it was possible to continue working.
Then i took the UMC-4 out and used force motors connected directly to Alexa Mini and everything was ok. Its not a mechanical problem on Rec button!

Anyone had this problem before?

I was told by Arri that if you are using three cforce motors with a UMC-4 (assuming you are doing this with the LCS to Lbus cable) there isn't enough power sent through that connection and you need to come out of the last motor and back in to a power source. I've never had a problem with it and I don't see why it would effect stop start... but maybe?

Hello ,

which cable do you use to connect the UMC-4 to the Mini?

best regards
Gernot

May I ask why you were using a UMC4 on a Mini? You were powering an accessory that is not needed. Come directly out of the body with the daisy chained Cforce motors, no? And, yes. Anytime you use 3 motors out of a Mini, you need to supply more power by adding it to the end of the chain of motors via PTAP or 3pin LBUS cables.

Hello
"I was told by Arri that if you are using three cforce motors with a UMC-4 (assuming you are doing this with the LCS to Lbus cable) there isn't enough power sent through that connection and you need to come out of the last motor and back in to a power source. I've never had a problem with it and I don't see why it would effect stop start... but maybe?"
- I have the LCS to Lbus Cable and extra power source cable LPS-7

"which cable do you use to connect the UMC-4 to the Mini?"
- ARRI cable UMC-4 to AMIRA/ALEXA Mini, K2.0001604

"May I ask why you were using a UMC4 on a Mini? You were powering an accessory that is not needed. Come directly out of the body with the daisy chained Cforce motors, no? And, yes. Anytime you use 3 motors out of a Mini, you need to supply more power by adding it to the end of the chain of motors via PTAP or 3pin LBUS cables."
I was having radio issues with WCU-4 + Alexa Mini on as Russian Arm and decided to add the UMC-4 and try if the radio signal was stronger...

Hello,

we made some tests with the same Setup you have and we cannot find the same problem.
We have no problem with run/stop like you discribe.
i dont think ist a firmware Problem.
It can be that the problem is the connector of the UMC-4 (maybe there is a faulty electronic part inside).
More i cannot say from distance.

Do you have the possibility to test a other cable on the CAM connector of the UMC-4 (to a other camera),
or to test if your UMC-4 in combination with your cable works with a Amira/other Alexa Min?

best regards
Gernot