Read: 3G Servo Bus Concern

[impi62]

I opened mine and there is some type of regulator powering the controller electronics.. I measured the output of the regulator and its 4.994 volts with any input voltage between 5.23 and 8.4 volts.. At input voltages below 5.23 volts the output of the regulator trails the input voltage by around 0.25 volts... The controller shuts down at around 3 volts.. Align state that current consumption of the controller is around 80mA.. Indeed 80mA would never melt the power supply wire. If that single wire were powering ONLY the controller electronics you would probably never have a failure. But its also powering the 3 cyclic servos.. I did another test.. I hooked everything up on the bench and connected a voltmeter to the servo bus in the controller.. The rig was supplied with a 6 volt lab PSU into a 7100R receiver. I added another voltmeter to the receiver servo bus.. Used 3 x 8717 servos to test. Applied power and voltage on receiver servo bus showded 5.96 volts while the one on the Align controller showed 5.81 volts.. The current drain othe LAB PSU showed 744mA.. Stirring the cyclic stick caused the voltmeter on the receiver to fluctuate around 5.9 volts while the one on the controller hovered around 5.40 volts.. That is with NO mechanical load on the servos.. Current consumption rose to around 1.6 amps.. Then I asked someone to hold the servos and apply some force onto the servo arms.. Still nowhere near stalling them but enough to simulate some loading.. Input voltage at receiver +- 5.86 volts while the controller bus showed lows of 4.1 Volts!!!! Maximum input current during this test was 7.3 amps.. You can clearly see from this test that the power supply wire on the receiver is adequately rated as it only dropped 0.1 volts passing a current of some 7 amps and the 4.1 volts on the controller bus clearly shows that the wire guage and sing connector are grossly inadequate as it caused a voltage drop of almost 2 volts at 7.5 amps.. 8717 servos can draw more than 10 amps at near stall... THIS IS AN ISSUE!!! It seems an external bus is the only way to do this until Align release an updated (Uprated) controller... FBL760 Ver2!!!

[harryboe]

impi62 - many thanks for backing us up with numbers here.

This is exactly what I would have expected. I also bet only 50% might be the wire and another 50% goes to those tiny servo connectors. They are even a bit smaller then the well known JST BEC connectors. I know the JST's are good for 7A. We know that 3 cyclic JR's can easily take more than that!

Even if the wire does not melt. Why should we pay for a high performance Servo if we finally run them on 4.1 Volts?

About the regulator. I assume that one is for the signal path only. There are two separate power channels for cyclic and rudder but to process the signals in the cpu you need to bring the signal voltage to the same level. Question have you checked if the 3G electronic receives the operational current from the cyclic or rudder channel?

[impi62]

[Even if the wire does not melt. Why should we pay for a high performance Servo if we finally run them on 4.1 Volts?[/QUOTE]

Good Point

[syn90]

impi62 - Thanks alot for the further research. This help to solidify our assumptions and proves that the one aileron connector is in fact insufficient and should by no means be used this way. After looking into wiring options that harryboe has been posting, I think I am going to stick with the wiring configuration I came up with that I posted previously. Some method of powering the cyclic servos beyond that one aileron connector should absolutely be implemented in every 3G installation. I am still beside myself with dissappointment in Align. I purchased my 2 3G kits knowing that there would be some growing pains with the first generation product, but I never suspected something this obvious and dangerous to plague us first adopters. Way to go Align.

[harryboe]

Syn90 - I looked a bit closer into you diagram. Should work as well. Personally i would not like the fact to have to "independent" cables mounted into one servo plug case. (RX-Side). I updated your diagram with my v2 cable proposal. Advantage. You don't have to open any servo or 3g connectors and it's simply plug-in.
Obviously you should use two such cables: one for PIT and one for ELE.

[syn90]

harryboe - I agree with you, I actually made an update that reflectes the exact same change you have made, and that's how I'm going to proceed with wiring mine.

[Heechee]

I wonder.. I don't have this thing yet, and I'm going to put it into a 500 trex only, but I'm reading the 500 3G manual that was posted on this forum..

Page 6 says:
The systems for swashplate and the rudder are independent circuits, supporting duo-receiver and duo-bec. (Example: swashplate servo 7.4V and rudder servo 5.2V)

I'm wondering how I should be connecting my AR7000 and CC BEC Pro with this 3G unit?
- Both BEC output cables to receiver?
- One BEC output cable to receiver and one to 3G?

[harryboe]

Originally Posted by Heechee

I'm wondering how I should be connecting my AR7000 and CC BEC Pro with this 3G unit?
- Both BEC output cables to receiver?
- One BEC output cable to receiver and one to 3G?

Unfortunately they are no "spare" connectors left on the 3G unit. One option is to use a standard "Y" cable to between the CC-BEC, ELE or PIT and the corresponding Servo. That should do the trick as the BEC is not carrying any signal.

Question. Why do you use a CC BEC pro if you have a ICE 75? The ICE BEC has the same spec as the Align stock ESC/BEC. Im running the Align ESC/BEC on 6V on a flybarless 500 (SK360/s9275 all over) for 1 1/2 years now. Never ever had an issue.

[Heechee]

Originally Posted by harryboe

Question. Why do you use a CC BEC pro if you have a ICE 75? The ICE BEC has the same spec as the Align stock ESC/BEC. Im running the Align ESC/BEC on 6V on a flybarless 500 (SK360/s9275 all over) for 1 1/2 years now. Never ever had an issue.

I don't, at least not yet. I ordered a bunch of stuff from ReadyHeli, and I ordered that just in case. Some people here claimed an external BEC is 'required' for flybarless use.

I guess I'll first try without the ICE BEC.

[kinosoo]

Hi harryboe
I think you need to rethink your modification. Correct me if I'm wrong, but you are powering your PIT servo with approx. 8 Volts from the 7100R, the AIL servo and the ELEV with 4.1 Volts from the controller bus. If thats the case then your swashplate will do some interesting things.

Cheers

[Ultraviolet]

Originally Posted by kinosoo

Hi harryboe
I think you need to rethink your modification. Correct me if I'm wrong, but you are powering your PIT servo with approx. 8 Volts from the 7100R, the AIL servo and the ELEV with 4.1 Volts from the controller bus. If thats the case then your swashplate will do some interesting things.

Cheers

I believe the cyclic power bus is connected so all three servos should still see the same voltage.

[panzlflyer]

So is the cyclic buss a common one? If so adding one extra wire would double the amp handling?

[Ultraviolet]

Originally Posted by panzlflyer

So is the cyclic buss a common one? If so adding one extra wire would double the amp handling?

It would appear so ( 2 extra wires ).

[panzlflyer]

So Im thinking 2 y harnesses with the signal pin removed had to do this on planks or somethin like that.
What were they thinking!!!!

[ShuNut]

Has Align said anything about this issue?

They need to step up &
: either confirm your servos will at times run @ only 4v or less or recall all units if its dangerous and can burn out,

: or deny this is an issue and defend their product.

I dont know too much about electronics but i've been following this thread and the info + the little i do know about electronic makes me scared of this unit.
It seems like they put a none needed weak fuse in the electronic system .
But also hard to believe Align could be so stupid to design a circuit like this.

Also i'm not looking to buy any FBL unit at the moment i am interested in them but i deffo would not get this 3G in its current state .

Peace

[kinosoo]

The servo bus powers all three servo in a normal condition (4.1 Volts max as indicated by impi62).
If you try to power that bus with 8.4 Volts from an external source one of three things I predict will happen.
1. There is an internal diode that prevents you from doing so, in this case you are powering the PIT servo with 8.4 Volts and the AIL, ELEV servos with 4.1 Volts.
2. The servo bus will be powered up with 8.4 Volts, in this case since the controller has an internal regulator 4.1 Volts. That is a potential difference of 4.3 Volts (reverse current possibly frying the controller)
3. Nothing will happen, and everything will work as you expected.
Here is my take on this and this is only my opinion, only way you can make this work is if you completely bypass the conroller bus and power all three servos from a completely separate high Voltage bus.
Good Luck experimenting with your 400 dollar electronics.

cheers

[panzlflyer]

well I made up a quick harness and hooked only the signal wire to the 3g, power from to the servo comes from the reciever and it works okay, so I guess I need to make up one more.
Im not taking pictures because it is kinda up in the air as to what connectors to use what a pita!

[panzlflyer]

I just check and on my 3g buss I get 6.61v same as is coming out of my spektrum

[PlasticHead]

Originally Posted by kinosoo

Here is my take on this and this is only my opinion, only way you can make this work is if you completely bypass the conroller bus and power all three servos from a completely separate high Voltage bus
cheers

This is a most reasonable thought, why would you want all the watts required to run 4 digi servos running through your high end multi gyro electronics, there is no need for it. The single power wire powers the FBL electronics then a separate buss powers runs the servos. It seems obvious and should be easy to wire up. It also seems obvious that one or more people at Align had a major brain fart.

PH

[gixxum]

Originally Posted by ShuNut

Has Align said anything about this issue?


I dont know too much about electronics but i've been following this thread and the info + the little i do know about electronic makes me scared of this unit.

Peace

and here is where i stand.

on my first flight with the 3g, i brought it up into a hover about 5 feet maybe, in normal mode.. just making sure everything was looking good and doing what it was supposed to.. less than a minute in the tail let go and starts to spin...no huge deal, i cut the motor and landed...i have no clue why it did that, and frankly dont want to use my 700 to try to replicate it. im not going to fly it as is, so now the 3g is holding my 700 hostage in the garage until align answers ANY of our questions, or i rip if off the thing and go back to what i (and everyone else) knows works brilliantly.

so now i have bought this "awesome all in one plug n play" system, that apparently has a mind of its own, yet with all the issues, especially this power one, align seems to have forgotten how to communicate with the customers that bought this system purely on hype and a video of szabo... i was sold.

man i miss my vbar.