Quark Monster Pro and UBEC

Hi all, confess I’m a bit puzzled. Here the problem:

Last week I’ve setup a Quark Monster Pro ESC with an UBEC (http://www.rc-monster.com/proddetail.php?prod=6vubec). Following the Quark instructions to disable internal BEC, I removed the red wire from the connection beetween the ESC and the Receiver (slot 2 on Futaba P3 FM receiver) and connected the UBEC to the receiver (to the B/C slot).

All worked fine. This morning, wanting to install a switcher between the UBEC and the Receiver, so not to have the receiver powered as soon as I connect the batteries, I removed the UBEC connection from the receiver and discovered, with quite surprise, that the receiver was still powerd by the ESC connection, even if the red wire was not connected !

Is this normal ? Have You any idea about that ?

Bye.
Edit/Delete Message

[BrianG]

Just to get this straight; you removed the red wire from the Quark's throttle cable? If you did this and there is still power with the UBEC removed, then you either have some capacitance in the receiver or are getting power from something else. Do you have any fairly detailed pictures of your setup?

Originally Posted by BrianG

Just to get this straight; you removed the red wire from the Quark's throttle cable? If you did this and there is still power with the UBEC removed, then you either have some capacitance in the receiver or are getting power from something else. Do you have any fairly detailed pictures of your setup?

Oops...it was my fault (ok, a stupid one) ! I've connected the negative wire to the switch, so the Receiver was always powered whether the switch was ON or OFF).

Changing the switch connection solves the problem.

Thanks and Happy Easter to everybody !

[BrianG]

Lol, ok. Glad you figured it out. It wasn't a stupid mistake - it was just an oversight. :) It happens.

The ESC must have been using the signal wire as a ground reference, and since the duty cycle of the signal is so low (it is mostly at 0v), it could sink enough current to power the receiver. Although, I bet your servo wouldn't run.

I think this is why most switches are set up so they switch both the + and - wires using a DPST switch.

Happy Easter to you too!