Hitec hs646wp acts funny @ 7.4V

[Dualdigger]

I've got a 646wp that i've been running off a sr300 and tekin fxr. I decided to install a cc bec for the servo but when the voltage to the servo goes over 6volts it acts funny, the servo is knotchy and is slow to come back to zero, almost like it's sticking. I have the bec wired correct, red wire from fxr pulled and bec added to bind slot in my sr300. When I remove the bec the servo seems fine,when running the bec @6.0v its better but not perfect-anything over 6.0v it acts up. Has this happened to any one before? Could I have a bad bec?

[89lxmorepower]

Nevermind i got info mixed up

[Dualdigger]

Originally Posted by 89lxmorepower

Its only rated at 6 volts and not sure it bec should be hooked into bind spot

The hitec 646wp is rated for 7.4 volts and using the bind port is acceptable. Any other thoughts?

[indiana mudcat]

I think Spektrum sometimes has issues with BEC's plugged into the bind port unless the signal wire is pulled from the BEC. The Y harness method of bypassing the rx also works around this.

[John82601]

I run my bec through my Spektrum receivers also. I have them programmed at 6.8v but I run a capacitor in either the bind or the aux port. Mine would act up also with decent to high-power servos plugged in.

Have you isolated it by trying a different servo? I ask because, for me, it was a Spektrum thing, not a servo thing.

[JeremyH]

Originally Posted by indiana mudcat

I think Spektrum sometimes has issues with BEC's plugged into the bind port unless the signal wire is pulled from the BEC.

Signal wire in the BEC?

[indiana mudcat]

Originally Posted by JeremyH

Signal wire in the BEC?

Just there for programming, I guess sometimes it can back feed a little and cause their rx's to keep rebinding.

[pravesh736]

plug the current wires from the bec directly to the servo and let only the signal wire(white/yellow not the red n black) come from rx . and reinstall the red wire n othrs coming from the esc into the rx. that way u have two bec being used. one for rx and etc , one only for steering servo . solved my glitching problem , sr300. ;)

[pravesh736]

Definitive wiring diagrams for BECs Rx Servos Motors etc.
last or second last diagram of the first page helped me solve my problem

[Dualdigger]

Originally Posted by John82601

I run my bec through my Spektrum receivers also. I have them programmed at 6.8v but I run a capacitor in either the bind or the aux port. Mine would act up also with decent to high-power servos plugged in.

Have you isolated it by trying a different servo? I ask because, for me, it was a Spektrum thing, not a servo thing.

Its funny you asked this, I did try another servo. I plugged it into my hitec 7954 in my wraith and it worked fine at a higher voltage. That servo is installed in my wraith with a xl5 esc and a flysky rx. I tried using the same cc bec in it and it glitched the esc. I thought they were not compatible so I installed it in my honcho(with the fxr and sr300) only to get a glitching servo. Honestly I had chaulked it up as a bad bec, but now you've got me wondering. What kind of cap do you run in your spektrum rx's?

Oh and when the bec was installed in the wraith(flysky-xl5-7954) I hooked it up both ways, but not in the honcho(fxr-sr300-646wp)only red wire pulled on esc method.???

[Dualdigger]

Originally Posted by pravesh736

plug the current wires from the bec directly to the servo and let only the signal wire(white/yellow not the red n black) come from rx . and reinstall the red wire n othrs coming from the esc into the rx. that way u have two bec being used. one for rx and etc , one only for steering servo . solved my glitching problem , sr300. ;)

I will try this as well, it's funny these things can get me so mad sometimes, I just need to walk away and come back to it later. I tend to just go back to what works. Heck I'm running a hitec 7954 off the internal bec of a xl5 cause of this.

[pravesh736]

i have no experience with the xl5 but wont the internal bec of it be damaged by running 7954 which consumes lots of power. i have read somewhere in this forum that if the servo torque is more than approximately 200oz/in u need external bec.

[spillproof]

If you bypass the RX and connect all your grounds it will work. One of the things lacking in those diagrams is a 3 way ground between rx, bec, and servo. I had glitching until i did this.