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Old Apr 15, 2003, 09:39 PM
Registered User
Tullahoma, TN
Joined Jul 2000
986 Posts
Jeti ESC with UBEC Problem

My friend is using a brushed Jeti 50 and a UBEC. The brake on the ESC is set with a jumper so I'm thinking it's an older model ESC. The red wire on the ESC connector going into the receiver has been disconnected to disable BEC.

The problem is the ESC will operate the throttle regardless of whether the ESC switch is on or off. My buddy hoped that he'd be able to apply power to the UBEC to power his receiver and when he was ready for throttle, he would switch on the ESC. (I have a UBEC with a 70-amp BL Jeti ESC and that's the way it works for me.)

Does the ESC switch simply turn the BEC on and off? We don't think we have a short in the switch...any ideas?

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Old Apr 16, 2003, 01:11 AM
Speed Demon
GregG's Avatar
Joined Dec 1999
12,364 Posts
It sounds like the switch should be in the negative lead of the speed control-RX. This question is probably better suited for the "Power Systems" forum. I'll move it there for you.
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Old Apr 16, 2003, 02:15 AM
Our Daddy and Heli Junkie
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In Heli Wonderland
Joined Aug 1999
22,817 Posts
With the red wire disconnected, the ESC still gets power from the battery when connected.

The RX should get no power unless the Ubec is connected to the battery too, so the RX should not send a signal to the ESC.

Double check your connections, something does not sound right.

It sounds like you are trying to leave the battery connected when not flying and use the switch for an On-Off switch. Very bad idea!!
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Last edited by Fred Bronk; Apr 16, 2003 at 02:18 AM.
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Old Apr 16, 2003, 07:59 AM
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
The Jeti's simply use the switch to interrupt the power going to the Rx. Without a Rx signal, the ESC will not run (you hope). So when you disconnect the red wire, you've effectively just turned off the switch. If the Rx has power from elsewhere, the ESC will work as if it was turned on.
Using any kind of switch to disable the motor is just a false sense of security. If the battery is plugged into the ESC, the system could fire up at any time. Don't plug in until you're ready to go, and then treat it with respect.
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Old Apr 16, 2003, 08:05 AM
jrb's Avatar
Edina, MN, USA
Joined Oct 1999
11,534 Posts
The switch on the Jeti 50 only turns off/on the power to the RX; it between the BEC regulator and the RX connectors red lead.

In fact, you donít have to remove the red lead to the RX as long as you donít turn on the switch.

This info is direct from L.A. Johnson of Hobby Lobby, who also told me that you can use the Jeti 35 & 50 for a higher cell count 14 & 16 as long as you didnít turn on the switch. He suggested taping it off and stuffing it inside the fuselage.
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Old Apr 17, 2003, 06:14 PM
Registered User
Tullahoma, TN
Joined Jul 2000
986 Posts
Assuming what jrw and Andy are saying is true, then we don't have anything wired wrong--everything is functioning as designed. We will certainly continue to treat the props with respect any time power is on the ESC and we do not connect the battery to the ESC unless we're ready to fly.

It's nice to get confimation of just what the Jeti ESC switch does--it switches power to the rx--and that's it. The ESC is powered and power could be delivered to the motor. Careful, everyone!

Now, how is the design different with a brushless Jeti ESC such that with a UBEC powering the rx, the motor won't turn until the switch is on?

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