Alexa, BFD receiver and digital M 1 motor, Terradek 2000, Cine tape.
3 batteries, one for Monitor, one camera and one Aux
Switch in 24 volt.
Camera turned on just fine, while the assist added another terradek, a bolt this time to the bottom of the sled to Tx to a close by Directors Monitor, and plugged that one into the D tap on the AUX side of the sled, we then added an eye brow, adjusted the motor, positioned the top mounted terradek 2000. so over a minute+ has passed by.
I looked and the Alexa display was showing 32 volts, actually 32.X, not exactly sure what the ._ was, but it was over 32 and under 33V.
Then I noticed the buttons on the operating side start flashing and on my monitor the bottom of the Frame said Error, although the image was still there perfect. I looked at my batteries, specifically the two powering the camera in 24 volts and the one on the aux side was flashing it's display, although still said 2 Hr + on it.
We turned everything off, I swapped out the camera power cable to another one, and swapped out the batteries for good measure. started the camera up, and immediately the same thing started, the flashing and the AUX battery display flashing as well.
We did not have time to keep trouble shooting, so off came the power cable and we slapped a battery on the back of the Alexa and worked the rest of the night just fine.
ANyone else ever have this or something similar happen with an Alexa in 24 volt mode on a sled?
I've experienced a similar problem you mentioned, the ac luckily found out quickly what the problem was in our case. The discharge of the camera batteries was unevenly divided, which caused the Alexa to compensate and draw more power from one battery than the other (or at least in theory according to the ac). The moment we reconfigured the power management and let the evildoer (umc-3 receiver in our case) run off the monitor battery instead of the one of the paired 24v set for the camera.
This was the solution in our case, I hope it was helpful.
That was the question I forgot to include in my last post. Which battery is responsible for the lower d-tap? I recon it would be either the camera or aux battery, most logically. On my sled (baerbel) all the lower electronics draw from the monitor battery.
The problem I had was at the top side, choosing aux power for the receiver causing the power imbalance, which is why I thought it would relate to your problem.
Perhaps there's a way to redirect the d-tap on your cinelive to draw from the monitor battery?
One more side note, We didn't experience the same problem when running the Alexa on 12v (same setup, acc,...) with the 2 exact same batteries running parallel, different cable though. The dp however preferred having it on 24v for reasons still unexplained. At the end of the day, you did the right thing putting a battery on top, always a safe alternative.
The Aux battery, along with the Cam battery, powers the 24v pins on the camera power connectors, and the 12/24 accessory lemos. It also powers the P-tap you used on the side. The other P-Tap is powered by the Cam battery.
The Cam battery always powers the camera, and all the 12v accessories - 3pin Lemo, 4pin Lemo, 4pin Hirose, as well as that Ptap. Mon powers the monitor. With a jumper block switch (unless gen 4 base) the Cam and Mon batteries can be put in parallel to power the camera, monitor, and all accessories in 12v from 2 batts.
When you have the rig in 24v mode, the aux plate, any batteries on it, the P-Tap on the plate, and (though I do not have a Cine Live myself to test this last one) the aux P-Tap on the sled base are all sitting at 12v above ground. The way 24v works on the PRO, as well as most other rigs, is that the Cam battery is running as it always does, and the Aux battery is switched in such that it's negative pin is connected to the positive terminal of the Cam battery, and it's positive pin is connected to the 24v outputs on the sled. So, if the Aux P-Tap on the sled is wired in as I believe it is, you were quite possibly shorting out one of the batteries by plugging the transmitter into it.
This is why there's a warning on most current Tiffen rigs to only put batteries on one of the battery plates in 24v mode - people were putting their transmitters on there between the battery and the rig, and frying them. I would make a note of it yourself - perhaps add some labeling to the rig to note that none of the Aux P-Tap connector on the sled (and perhaps even on the plate itself!) should be used in 24v mode. The Cam P-Tap connector should be safe to use in any mode though.
If you are right Tom, that would likely explain 2 of the problems I had with 24v on Cinelive. But it would also mean I was misinformed by Pro.
Assuming you are correct: why does plugging in the transmitter short the battery? I've metered that Aux P-tap at 12v, correct polarity, when in 24v mode. Why does plugging in a 12v device affect anything in any other way?
Bare with me if this takes a bit to explain - I'm on set right now sitting behind a 66x broadcast lens, waiting and playing on my phone. I'd be better at explaining this on a real keyboard!
Yes, you can absolutely meter the proper 12v across that P-Tap, because the P-Tap is just connected to the positive and negative terminals of that one battery, and therefore only has 12v across it. The problem arises when you plug in a device to that P Tap that is connected to anything else. For example, a video transmitter. The camera has it's video output BNC shields sitting at ground. Ground for it is the negative terminal of the Camera battery. Ground for the video transmitter is the negative terminal of the Aux battery, which is shorted to the positive terminal of the Cam battery for use boosting to 24v. Connect the BNC connectors, and suddenly you're shorting negative to positive. I blew out a camera's whole video output board in a very similar way once!
Now, if PRO told you otherwise, it's possible they've wired it all up differently, but I don't see how you could get 24v without putting the two batteries in series. If you want to test, put your multimeter in continuity mode, switch your rig into 24v, and see if you've got continuity between the negative terminal of the Aux P-Tap port and the Camera battery plate's positive terminal, or vice versa.
I do believe 24v is achieved through series on the Pro sleds, and my limited understanding of how that is achieved is the way you explained it.
I still don't quite understand, but you're definitely confirming my hypothesis. It's been a long time since I had the phone conversation with Pro, so I can't say if they strictly gave me incorrect information. However, if you are correct, I it seems to me that would have been an easy answer from them to explain my problem (and another I never told them about, and Ozzie's). I was told it couldn't have been caused by the rig. Time to talk to Jack! Thanks for the help!
I said for Tom to be correct, Pro would be wrong. The assumption I made is that Pro is correct. In the interest of trouble shooting a problem with no current answer, I asked Tom for more information. Tom is also not claiming to be correct so far as I can tell, he's just offering ideas. At present I have taken Tom's ideas to Pro and they are helping me work through it, as expected, because they're helpful like that.
I later amended the initial thought in a new post and said that for Tom to be correct, Pro COULD be wrong. I stand by that. I never make assertions I don't believe fully to be fact, and I have no hard facts here, thus no assertions.
Everyone is fallible. Me, Tom, everyone at Pro, even Jack. That's right, EVEN Jack, come at me bro!