Spektrum / JR servo issue

[lincpimp]

Having a strange problem with a dx6/ar6000 radio system. It does not like jr servos, namely 9100t and 8711. I have 2 of each of these servos and all 4 of them will make the receiver shut down, then restart. Does not matter if there is any load on the servo, or what channel you plug it into.

I have tried other hitec and futaba servos and they work just fine.

I am using a ccbec with a 2s lipo. Lipo is charged and the ccbec is not shutting down.

Seems like it is a signal issue, or the jr servos are putting out some sort of interference?

I tried unplugging everything from the rx save for the ccbec and the jr servo, but the problem still exists. I can unplug the jr servo and everything works as normal...

Any ideas?

[BrianG]

I can think of two possibilies:

1) The servo is "noisy" and injecting too much interference in the power line which is affecting the receiver. Adding a cap on an unused receiver port may help. Also, if you have a ferrite donut, wrap the servo's leads through it. Both those should help if the issue is noise.

2) For some reason, the servo is drawing more current than expected, even unloaded. Could be a mechanical issue (worn bushings/bearings at the gear assembly) internal motor is getting worn, etc. Do you have a way to monitor the BEC voltage and watch the instantaneous voltage as you actuate the servo (a digital meter sampling rate may be too slow)? If the voltage dips too much, chances are excess current is dragging down the BEC too far.

[lincpimp]

Originally Posted by BrianG

I can think of two possibilies:

1) The servo is "noisy" and injecting too much interference in the power line which is affecting the receiver. Adding a cap on an unused receiver port may help. Also, if you have a ferrite donut, wrap the servo's leads through it. Both those should help if the issue is noise.

2) For some reason, the servo is drawing more current than expected, even unloaded. Could be a mechanical issue (worn bushings/bearings at the gear assembly) internal motor is getting worn, etc. Do you have a way to monitor the BEC voltage and watch the instantaneous voltage as you actuate the servo (a digital meter sampling rate may be too slow)? If the voltage dips too much, chances are excess current is dragging down the BEC too far.

1, will give this a try.

2, all 4 jr servos did the same thing. so i figured it was something related t the servo desing, not a single bad servo.

I will report back in a few.

[lincpimp]

Ok, figured out the problem.

I gave a "glitch buster" style cap a try. It helped, but if you rapidly cycled the 9100t servo it would shut down the rx. Tried a few other servos, but they would all do it some of the time.

Hooked the ccbec up to castlelink and upped the voltage to 6.5v. That helped some. So I had a look at the ccbec while I was cycling the servo. The green light was kicking on and off under load. Bingo, bad ccbec.

I only had one other bec aviable, it is the one that BrianG had wired to a used MM he traded me. Hooked that up and no problems. I even hooked all of the servos I had up (total of 4, summit diff locks, tranny shift and steering) and stalled the 9100t with my hand and the bec system worked without a hiccup.

So I have a ccbec that must have an issue. Will have to send it back to CC. First time I have had an issue like this. I am just glad it is not a defective rx. The ccbec was brand new for this application so I am sure it is under warranty.

Thanks for the help BG.

It seems some of the newer CC becs have trouble keeping up with high amp servo's, yet swap in an old one and it will work fine. There is an entire thread dedicated to this on RCC and I believe castle is well aware of the problem but they haven't seemed to be able to find a fix yet.

Kieren