7950 super glitchy!!! Please give your opinion, I'm at a loss?

[FlightInstrukta]

Let me start by saying, this rig and all electronics were in perfect working condition 2 days ago, then sat in the basement for last 48 hours, and now this!!!
(Moisture may have something to do with it, basement is pretty humid)

Servo problem - YouTube

My current setup is a MMP w/ tekin redline 10.5 sensored brushless, spektrum DX3S SR3100, hitec 7950 w/ CC BEC and HH Rx by-pass adapter. Everything has worked seamlessly for several months until this servo problem?

I initially thought my servo was finally dead, so I got another 7950 from the parts box, only to have the same shaking? I then tried to replace the HH by-pass adapter wit a new one to see if that was it? Nope!!! Then proceeded to try a couple different spektrum Rx's and also different combinations of servos, and with and without the BEC, and with and without the by-pass adapters. Even tried running the Rx off of a seperate battery pack to eleminate the ESC as the culprit? I pretty much tried every combination of electronics I could imagine trying to eleminate every possibly source individually, and have the same results every time? I tried a couple different lipos to make sure I didn't accidentally grab a dead one? Tx has fresh batts in it? I tried 3 different servos, 2 Rx by-pass adapters and 3 different Rx's in multiple combinations and, I think I'm starting to loose my mind?

Normally I wouldn't ask for help, I'm usually pretty capable, but this one jus seems to be really trying my patience... It's got me wanting to break stuff!!!

If anyone has any suggestions that I may not have tried yet, I'd love to hear them? Thanks in advance for any input!!!

[FlightInstrukta]

Forgot to mention, it will still operate while doing this so it's still getting a signal. It will steer left or right, but seems to go way past the pre-set end points, and ESC and motor still work fine, but can't seem to track the source of the shaking?

[LuckyDevil]

Do you have the programming unit for Hitec? You can adjust sensitivity and all.
I'd look into that. Never had quite that problem. Good luck!!!
But sounds like if you tried other servos, that's crazy!!!
Maybe a programming between to transmitter settings and the servo settings? not liking each other.
Shooting in the dark.

[FlightInstrukta]

I don't have the hitec programmer. I've been using 7950's for a couple years and have had at least a dozen of them. I've never seen anything like this?

[JohnRobHolmes]

What is your CCBEC set to, and did you check the voltage getting to the servo? This twitching can happen when voltage is high and it makes servo gain too much.

[FlightInstrukta]

Originally Posted by JohnRobHolmes

What is your CCBEC set to, and did you check the voltage getting to the servo? This twitching can happen when voltage is high and it makes servo gain too much.

The BEC is set to 7.4, and is currently running the newest firmware.




I tried lowering the voltage to 7.0 and same twitching. I tried to step back the firmware to the 1.0 beta version and the BEC would not turn on apon plugging a battery in? I currently do not own a multi-meter, so I am going to the hardware store now to pick one up. I'll report back shortly with the actual voltage output of the BEC. Thanks for the responses so far guys!!!

[FlightInstrukta]

Originally Posted by JohnRobHolmes

What is your CCBEC set to, and did you check the voltage getting to the servo? This twitching can happen when voltage is high and it makes servo gain too much.

Ok, so I updated the firmware back to 1.03 or whatever, to get the BEC to work again, then stepped the voltage down to 6.0v to see if there was a difference. Nope!!! Same exact problem. I also got a Klein multi-meter to check the output voltage of the BEC, and it's exactly where I set it and doesn't fluctuate a bit.



Now I'm really confused? I was kinda counting on it being a bad BEC after reading a few other threads on the topic? Now I'm kinda at a loss as to what to eleminate next? I've eve tried eliminating the simple LED controller from the wiring to see if that was it. I've tried eliminating the BEC and running the servo off the ESC's internal BEC wit just the servo and ESC plugged into the Rx? Any other suggestions would be greatly appreciated? Thanks

[JohnRobHolmes]

Sounds like the servo and RX are not getting along. Is there a setting on your radio to change a channel from analogue to digital? Have you tried plugging the servo into other channels?

[FlightInstrukta]

Originally Posted by JohnRobHolmes

Sounds like the servo and RX are not getting along. Is there a setting on your radio to change a channel from analogue to digital? Have you tried plugging the servo into other channels?

On the remote, I went into the settings and changed the frame rate from 11ms to 16.5ms, and still get the same twitchy results. Then, not sure if its help, chenged the RF Mode setting from standard to FR(not sure what that means) and still have the same twitchy results.

I'm gonna pull everything out of the vehicle to check for possible frayed wires touching metal, or each other? And then at least have everything in front of me, where it may be easier to potentially spot the issue. While I'm at it, I'm gonna set up a seperate Rx w/ BRXL and brushed motor to test these servos on and see if I get the same issue with another power source? I'll report back wit my findings after dinner. Thanks John!!!

[FlightInstrukta]

So, I got out another ESC (BRXL) and a different Rx, and tested the servos, both of these 7950's in question still have the same twitching problem. I tried a traxxas 2075 on the BRXL bench setup and it worked perfect. I then tested the 2075 servo in the rig in question, and the servo worked perfect.

So somehow I had not 1, but 2 7950's go on the fritz on me the same day? This leads me to believe there is still something in my system that caused this problem, but not sure since the traxxas servo worked fine? I have one more spare Servo(9100THV), but I'm hesitant to put another high $ servo in this system only to cause it to have the same problem? Any thoughts on this would be mucho appreciado?

How's hitecs customer service? Is it likely that they will fix them for me?

[JokersWild]

I had a Jr servo do that but it was a warn pin home in front case causing the pot to not align correctly and caused the chatter. Seems that it did it at a lower rate when it was on its wheels and got faster when unloaded.

That's what I would say if it was on one servo but odd its on two. I would do what Rob said and put on another channel. Guess all to do it trouble shoot and toss it in someone else's rig?

[FlightInstrukta]

Ya, I forgot to mention above, but I already tried the servo on another channel of the Rx? Got the same results. Both servos start the twitching as soon as power is applied to the ESC. Results are consistent on both esc's? Both servos are doing the exact same thing.

[Ryan87zuk]

I know you checked the voltage coming out of the bec, and different servos worked good. But those different servos you have tried are analogue correct? Wonder if that has anything to do with it? I have had two cc bec's die on me in the past two months. If you have another, try it. The bec's that failed on me- one didn't work from the start. Couldn't program it and when in the rig it made the servo freak out twitching. The second bec worked ok for literally two seconds before popping and smoking. Took out my brand new 7954SH in the process.

[FlightInstrukta]

I've tried it (both servos)with the BEC completely eliminated from the brushless setup. And it immediately starts twitching as soon as power is applied, as the motor is chiming to indicate cell count and startup of the MMP. I also tried both servos on a completely different setup (bench test) with no BEC and had the same results...

[Ryan87zuk]

Hmm. Sounds like two bad servos huh?

[FlightInstrukta]

Originally Posted by Ryan87zuk

Hmm. Sounds like two bad servos huh?

That's the only logical possibility at this point? Everything else in the system seems to be in good working order? I still have yet to hook another high $ digital servo up, but I will find out shortly?