Powerful Servo killing receivers?

[boldfin]

I’ve got ProTek 370TBL servos in six of my rigs. I love the power, and I have had no issues whatsoever on all but one rig. The five rigs that are running Hobbywing 1080’s and brushed motors have been flawless. I am able to run the internal BEC on the 1080 ESC’s at 7.4V in those five brushed rigs and I haven’t found it necessary to use an external BEC. But I have one rig with a Hobbywing AXE 540 system, and it keeps blowing receivers. I’ll be creeping along slowly, and all of the sudden the rig just stops responding. The ESC starts blinking red continuously. I am unable to re-bind. It’s done this now twice, and I’ve had to replace two Spektrum SR310 receivers.

The guy at our local hobby took a look at my rig. We installed the Spektrum SR310 Rx in another rig, and it was non-responsive – appeared to be blown. Installing a new receiver has brought my rig back to life twice now. But we’re not sure what is killing the receivers. He thought the 370TBL servo was likely the issue. He recommended I install a glitch buster to start, and maybe drop the internal BEC voltage back down to 6.0V and see how it goes.


I installed a glitch buster and ran it yesterday at 6.0V. I definitely missed the extra torque at 7.4V. But at least it didn’t blow up another receiver.
Any idea what is causing the receivers to fail? Is it possible that the 370TBL servo is somehow backfeeding into the receiver? Would a Rx Bypass alone help? Or do I need to install an external BEC? I have no other accessories on this rig - no lights, no winch, etc.

Once I figure out what is killing receivers, ultimately, I’d really like to bump the ESC’s internal BEC back up to 7.4V. I just haven’t heard of this being necessary on the ProTek 370’s. I know lots of people who run powerful servos at 7.4V without a BEC. Like I said, I’ve got five other rigs running Hobbywing 1080’s at 7.4V with ProTek 370TBL’s in them without an issue.

Just wondering if anyone else had had issues with blowing receivers when running ProTek 370’s on Hobbing AXE systems without an external BEC.

 

[Omsk]

Your ESC settings are killing the receivers.
They can't handle the 7.4v the ESC is giving.

 

[HumboldtEF]

Those receivers are rated for 3.5-9.6V so that shouldn't be it.

I would suspect the servo and pull it out as a test. A bad servo can do some odd stuff and back feed voltage to other components.

 

[tuxstang]

Don't know how much amps the 1080 and the AXE can provide peak, but as the AXE provides 1A more than the 1080 continuous, I guess it provides more peak than the 1080, which seems more than what your receiver can handle when the servo calls for power ...

 

[Omsk]

Those receivers are rated for 3.5-9.6V so that shouldn't be it.

Thanks for correcting me, I thought that receivers were limited to 6V .

 

[boldfin]

Don't know how much amps the 1080 and the AXE can provide peak, but as the AXE provides 1A more than the 1080 continuous, I guess it provides more peak than the 1080, which seems more than what your receiver can handle when the servo calls for power ...

Thanks for your reply. May I ask where you are getting that info? The manuals for both the 1080 and the AXE system show the same thing for BEC continuous output, and don't state anything in regards to peak output.

BE#C Output 6V/7.4V Switchable, Continuous Current of 3A (Switch-mode)

 

[Greatscott]

Thanks for correcting me, I thought that receivers were limited to 6V .

Some are, Traxxas RXs are only rated to 6VDC. I have fried a couple of them that way.

To the OP...
You could power the servo directly, bypassing the RX's power.

 

[Inspector86]

I would recommend running one of the CC 10A BECs and Holmes Hobbies by pass harness that way you could run the servo at 7.4 and the reciever at 6v. At the very least it would isolate the servo from the receiver.

https://holmeshobbies.com/electronics-and-wiring/wiring-and-wiring-accessories/holmes-hobbies-rx-bypass-adapter.html

 

[tuxstang]

Thanks for your reply. May I ask where you are getting that info? The manuals for both the 1080 and the AXE system show the same thing for BEC continuous output, and don't state anything in regards to peak output.

BE#C Output 6V/7.4V Switchable, Continuous Current of 3A (Switch-mode)

Directly from HobbyWing's shop :

AXE :
https://www.hobbywingdirect.com/products/hobbywing-axe-550-system-for-rock-crawler
BEC Output 6V/7.4V Switchable, Continuous Current of 4A (Switch-mode)

1080 (need to select the "specifications" tab) :
https://www.hobbywingdirect.com/products/quicrun-wp-1080-brushed-esc?variant=26223842568
BEC Output 6V/7.4V @ 3A (switch mode)

 

[boldfin]

Directly from HobbyWing's shop :

AXE :
https://www.hobbywingdirect.com/products/hobbywing-axe-550-system-for-rock-crawler
BEC Output 6V/7.4V Switchable, Continuous Current of 4A (Switch-mode)

1080 (need to select the "specifications" tab) :
https://www.hobbywingdirect.com/products/quicrun-wp-1080-brushed-esc?variant=26223842568
BEC Output 6V/7.4V @ 3A (switch mode)

Interesting. The manual for the AXE 540 says 3A.

I'm going to reach out to Hobbywing support tomorrow to see what they have to say. Might also give AMain a call to see if they have any experience with the 370TBL servo causing issues with receivers.

I do have CC 10A BEC and HH Rx Bypass that I can install as well.

Thanks to all for the suggestions.

 

[meatmonkey]

I'm not sure how you have your bec wired, but I've had issues with powering strong 300+oz/in servos through Flysky receivers. Seems some receivers dont like passing the 5+amps some servos can draw. I now solder the bec output wires directly to the servo wires, leaving only the servo signal wire plugged into the receiver.