600 trex600 cyclic issues

Hi folks hope everyone is having a great day today...
Today I come to you wise folks with an issue that has boggled my mind. My trex 600 seems to get posses when all 3 of my cyclic are connected to the Rx.... he is some background so I can paint a better pic.
I have tested each servo separately thru the Rx channels and they behave, but at soon as all 3 are connected to the Rx and only the cyclic servos are connected...no rudder, no gyro, esc because I use a external BEC. They begin to jump and make the Rx cycle on and off very quickly. I am at a lost here any help would be appreciated.
My setup is
Jr ds-8717 for cyclic
CC 10amp BEC
Frsky Rx X8R and VF8II(I think that's the model) but either way it happens with both Rx
 

holtneil

Active Member
Hi mate it may be the refresh rate of the servos , try running in a low rate and see if this helps
 
Hi mate it may be the refresh rate of the servos , try running in a low rate and see if this helps

What do you mean low rate? Cause I haven't even messed with any of the settings I just plugged them in the Rx and had my Tx with a simple 6 channel template setup just to get the servos mov8ng in the right direction for FB head setup....
 

holtneil

Active Member
in some transmitter you can change the servo refesh rate in the servo set up , we normally do this in the FBL unit but as you didnt say if it was FBL you can do it in the transmitter
 
I will have to check this out when I get home...thanks, weird tho I have been scouring over forums and people that use these servos say they are awesome to have but no one has mentioned what you have....maybe I am that one unlucky dude....lol
 

holtneil

Active Member
I may be wrong but its worth a check . Tony or Smoggy are the men to chat too they have both forgot more than i will ever know , Smoggy has a trex 600
 
And that's why I come here for help.....this small tight community is always happy to help out! Thank you to you for the tip and thanks to anyone that contributes to helping me with this issue...cheers
 

holtneil

Active Member
I just had a chat with Steve on the phone ( smoggy) he is going to try and catch up with you but he did say its not the refesh rate , so sorry i was wrong any way Hope Steve can nail it for you
 

Smoggie

Well-Known Member
Hi, What Neil is referring to is 'Frame Rate' which is adjustable in some transmitters. I could conceivably be the problem but at least in theory because your servos are digital which should work with faster frame rates without any issue.
Normally when you get this sort of problem I'd suspect an issue with the poser supply to the servos but your CC 10A BEC should be perfectly ok for powering three standard servos. What may be worth a try is adding a 'Brownout capacitor' to the system.

Two x 10V 4700mAh caps do this job fine, I'll take a pic to show what it should look like.
 
This is some testing of capacitors to prevent 'Brownout': YGE 90/120LV 5,7V 6/12A BEC with capacitors | VStabi

So you saying I should try and use the same ones you have on yours? Should i try adjusting the voltage output on the BEC? Cause as of right now I have it set to the far end of the servo specs which is 6v but I know they can go as low 4.9v I believe.
I use two of them wired into a servo type plug, here is a typical installation on my Trex 700X:
View attachment 17934
 

Made a quick video to show you now what the servos are doing when I added a capacitor I forgot I had from Savox servos.......does anyone know why this is happening?
 

Tony

Staff member
The servos are binding both high and low. You need to reduce the travel of the 3 servos collectively.
 
Yes I saw that, but last night I was even getting that far with my progress it seems like today I got it to calm down by adding a single capacitor that I had laying around, and is that normal when binding? I have seen servos bind on my smaller heli before I can correct them and I have never seen them bounce like this before. I thought when a servo binds it hums loud and gets hot....lol
 

Tony

Staff member
No, it is definitely not normal when they bind and you really need to reduce the travel so that they stop binding. When they bind, they pull an amp spike that is beyond what the BEC can handle and thus it pretty much resets causing the bouncing. That is what I'm thinking anyway. In any case, you really need to stop the binding and I'm sure all of your issues will go away.
 
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