Sidewinder SCT ESC Issue
 

Hi guys, my friend has a sidewinder SCT system in his Slash and yesterday it started acting weird. Its like the BEC isn't supplying enough power so the steering servo barely works, the ESC fan speed varies when steering, and the receiver will shut of and reset every few seconds. I am thinking its a BEC issue with the ESC, but I'm not sure, anyone else had the issue?

I have seen this plenty before. Many of today's faster and stronger servo's demand too much current from BEC's. Many of us have found it good practice to use external BEC's. This is pretty much standard practice in the crawler world.

Its the stock slash servo though. I am guessing that sence this happened the BEC in the ESC is a gonner so should he send it back to Castle or just buy a BEC?

If it appears the BEC is getting weaker, then yes, I'd send it in. Even if you disable the BEC to keep it from powering servos/receiver, it still powers part of the ESC itself and a dodgy BEC can cause weird things to happen.

Once you get a fully functioning ESC replacement, I would disable the BEC (simply remove the red wire from the throttle cable) and use an external BEC to help keep the problem from happening again.

IIRC, the sidewinder uses a linear BEC, which can thermal when running at 3s voltages. An external BEC is almost always switching, and they are more efficient so there is less chance of thermalling with increased voltages (assuming the servo isn't pulling more current than the BEC current rating).

Also, you might want to check to make sure the servo is not worn mechanically, and that there is nothing resisting the servo action (like dirty/worn steering linkages/parts). Any of those would cause more drag, which causes the servo to draw more current and stresses the BEC more.

Alright, I will check out the servo next time I see him. Thanks for the help :mdr:

The internal bec isn't the strongest. I don't think there is a need to send it in, just add an external bec and disable the internal one