Read: 3G Servo Bus Concern

[harryboe]

Originally Posted by OnTheSnap

A bunch of local guys are buying the system and they don't troll the forums. This is going to be a HUGE mess for Align!!

HF Support!! Please make this thread a sticky and change the title to something very eye catching. This is a serious safety hazard.

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[marcioloko]

Originally Posted by harryboe

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[jockstrap]

I was looking at getting a 3G for my 450pro when I came upon this issue and had a look for myself.. yep - looks like it would be ok for a 450 and under but anything higher i'd be making a power harness for the servos..

It's a messy problem and looks like it stemmed from Align wanting a n nice tidy cabling solution and plug for the 3G

The fix should be very easy, just messy..

This is what I'd do and is along the lines of others..

1) remove the power pin from the servo plug on each of the 4 servos.
2) get 4 new pins from the local hobby store and solder a decent length of appropriate thickness wire to each one.
3) push them each back into the servo plugs.
4) route them through the frame to the output of the BEC and attach to the positive wire of the bec output - either solder directly or via a plug of some sort - up to you..

will make the wiring a bit messy but problem solved very cheaply..

I know you shouldn't have to do this but if you've already forked out big $$ for the 3G, you better do this of be prepared to fork out more money in crash repair..

an alternative to messy wiring is to run a heavy duty wire from the bec closer to the servos and then junction the 4 servo power wires to it..

Hope this helps if not mentioned before..

WOOPS EDIT: last minute thoughts - I'd probably be doing this for the black/brown earth wire on each servo as well - but obviously connecting them to the earth output of the bec... the existing signal wire does not need to be changed as it has little current going through it..

Edit #2: See post #80... shows what to do..

[harryboe]

Originally Posted by jockstrap

1) remove the power pin from the servo plug on each of the 4 servos.
2) get 4 new pins from the local hobby store and solder a decent length of appropriate thickness wire to each one.
...

an alternative to messy wiring is to run a heavy duty wire from the bec closer to the servos and then junction the 4 servo power wires to it..

Be careful here. The 3G has a power bus for cyclic and one for rudder servos. If you have a RX that also has two different voltage outputs (e.g. the AR7100) the you are going to shortcut these power out's.

One more comment. There are reports that it works fine in some cases while it does not in other cases.
One reason for that is the connector itself. Years back (when I was designing electric devices) we made some studies measuring the impact between contact pressure of the connector and the resistance of the connection. Short outcome: the impact is huge!
Therefore id your tiny servo connector is not really firm (because it was plunged out an in several times) or because it was used by another RX that widened up the connector, then there is a good chance that you will see massive voltage drops over that single connector.
Whatever you do, even on a 450 make sure your connectors are tight and firm to get a good connection without heavy voltage drops. (also true for the "home-made" external servo-bus cables)

[rubbersoul]

This might help to ensure connectivity.

[OnTheSnap]

And then use this to sooth your irritation after the 3g causes a crash:

[rubbersoul]

[Globs]

OnTheSnap has it

Contact grease only stops corrosion and some wear, and these units have none of that!!

Looking at the plug photos I'd say there were some serious QA issues there like bent connectors... I had a servo plug on an Acer-lab servo that made intermittent contact - that actually looked perfect but still didn't work - soldering on a el-cheapo HK extension lead plug solved it however. It's all in the details on those size plugs..

[rubbersoul]

back in my ham radio days, I used a lot of this contact grease on my antenna connectors to reduce signal loss. could work the same for servo connectors...

[Globs]

Originally Posted by rubbersoul

back in my ham radio days, I used a lot of this contact grease on my antenna connectors to reduce signal loss. could work the same for servo connectors...

I bet your antenna connections actually had bits of metal touching each other - looking at the sensor plug photos I think some are too bent to do that for very long..

[jwtje]

I think i will just buy 3 short servo extension leads take out the red wire on each and plug it in the reciever by the matching servos. 2 will be no problem since align already left them out just add to the plug the 3rd i will make a y connection. or will this not work???

[dr_cheeks]

Here was my simple easy fix for my trex 700 using the following setup
JR RD921 Receiver
3 x Futaba BLS 541 Servos
Flighttec 8A Linear Voltage Reg Running at 6Volts
Flightpower Eon X Rx 4200 2s2p Lipo

Bear In Mind I Had Already Fitted The Fylbarless system To Me Heli Before The Below Mods

1. Unpluged Elevator & Pitch Servo's From 3g Unit
2. Removed Red + & Black - Wires From Servo Plugs Then Split The Red & Black Wires From The White Signal Wire almost Back To The Servo.
3. Plugged Servo Plugs Back In To 3G Unit With only White Signal Wire In Them
4. Removed Elevator & Pitch Lead From Reciever That Come From 3G Unit Leaving The Aileron Conection With 3 Wires Alone.
5. Put The Corresponding Red + & Black - Wires That Come Direct From The Servos Into The Plug From The 3G Unit Originally Containing Signal Only.
6.Plug Wires Back In To Reciever Job Done :-)
No Extra Wires, Leads Or Soldering Required
Have tried to edit a previouse diagram to show what i have done

[layinitdown]

Could you post some pics,, I don't see how you are getting away with no extra wires or anything..

[Arven]

yeah that would make perfect sense. You could put a spare Servo plug on the 2 pins you removed from the original servo plug making it nice and neat. - Will look like a Gyro with 2 plugs on one wire...

You would still need to have the receiver very close to the flybarless unit, and you would have to strip / peel away the wires a bit down the cable to get the wires enough distance... Which could make them a little untidy later on if you wanted to use them as normal servos next time but not a worry for me...

Good idea!

[rubbersoul]

Here's a pic of what I did



Connector at bottom is from servo, connector at top is 3G connector to RX.

Removed Red and Black pins/wire from Pitch servo. Plugged pins/wire from pitch servo into 3G pit connector going to RX. Red wire goes into center slot. Pitch servo is now powered direct from RX. Plugged pit servo (now with only white signal wire) into 3G pit output. . Repeated the same operation with Elevator servo.

I have had no problems with AR7100R, 610s on 8v. Did this mod just to be on the safe side.

Edit: Since this is such an easy mod, I am thinking of doing the same thing on the aileron servo and plug it into a the spare throttle channel on the RX. That way, all three servos will be powered direct from the RX.

[bigote]

does SG Reactor-X eliminates this servo bus concern?, as far as i know reactor x uses direct power to the cyclic servos.

[thayghetucsb]

guys, this is mod recommended for T500 also? i'm running ds510 for cyclic and ds650 for tail.

[Arven]

Well i just did some bench tests with my 500.

I connected my Eagle tree to the heli and connected to my PC in Live mode.

I then bent the blades on a 45 degree angle (so that the servos have to lift around half of the blades weight) and did some pitch pump and moved the cyclic stick like crazy. I can hear the servos straining to lift and lower the blades etc but the maximum amps i pulled was 0.61 of an amp.

During flight it could be possible that the servos might pull more amps, but i would find it hard to believe it would be more than 1 or 2 amps.

I dont think we have to worry about the high amp loads on a 500 size heli. I'm sure that single cable and servo plug can supply more than enough current for the DS510 Servos running on 5.1v.

Cheers.

[thayghetucsb]

Originally Posted by Arven

Well i just did some bench tests with my 500.

I connected my Eagle tree to the heli and connected to my PC in Live mode.

I then bent the blades on a 45 degree angle (so that the servos have to lift around half of the blades weight) and did some pitch pump and moved the cyclic stick like crazy. I can hear the servos straining to lift and lower the blades etc but the maximum amps i pulled was 0.61 of an amp.

During flight it could be possible that the servos might pull more amps, but i would find it hard to believe it would be more than 1 or 2 amps.

I dont think we have to worry about the high amp loads on a 500 size heli. I'm sure that single cable and servo plug can supply more than enough current for the DS510 Servos running on 5.1v.

Cheers.

thanks, i'm glad you have the gadget to test it. I don't. i'm sure other T500s' on 3G are happy to hear about this.

[MXRACERX43]

Originally Posted by Arven

Well i just did some bench tests with my 500.

I connected my Eagle tree to the heli and connected to my PC in Live mode.

I then bent the blades on a 45 degree angle (so that the servos have to lift around half of the blades weight) and did some pitch pump and moved the cyclic stick like crazy. I can hear the servos straining to lift and lower the blades etc but the maximum amps i pulled was 0.61 of an amp.

During flight it could be possible that the servos might pull more amps, but i would find it hard to believe it would be more than 1 or 2 amps.

I dont think we have to worry about the high amp loads on a 500 size heli. I'm sure that single cable and servo plug can supply more than enough current for the DS510 Servos running on 5.1v.

Cheers.

Nice! Now if my BLS-251 twitch can be resolved I am good to go on the 500.
I am building my 600&700 FBL's with JR hV's and SGP Reactor X so I hope that takes care of those. I am holding off converting my last 600 running 6V 8717's and a Fromeco until the issue is resolved.

Align!!! Got alot of $$$ from me in the past 2 months .How about some answers?