Fried $250 worth of servos in 5 minutes.

[sierradmax]

I have two airtronics servos in my super along with the 1.5" servo arms on each. The links aren't mounted directly at 1.5", They are around 1.1" from the servo swing. I set the EPA's correctly through my DX6. As you can see from the picture below, the servo arm is longer than the standard 3/4"-1". hence, more effort is required through the servo.


The wiring diagram for the rig is as followed:


Electronics used:
3 cell 11.1 lipo
2x cc sidewinder
1x cc bec
1x AR6000
2x airtronics 94780

The rig ran flawlessly at its first comp for about 5 minutes and the servos quit working before the finish gate. Both were EXTREMELY hot. The rear servo has alot of resistance whenever you steer the tire manually. The front servo still works. However, when you attempt to steer the rear through the transmitter, the front starts glitching.

1. Should I use larger 1/4 scale servos?
2. Should I wire the negative of each servo to the BEC
3. pick up smaller servo horns?

BTW, Airtronics only has a 30 day warranty

[hitman46mod]

Looking at your wiring diagram you still have the a power lead coming from the second ESC disconect it. You only need power coming from the BEC. I did the same thing on my super and forgot to pull the second power lead from the rear ESC. My ESC shut down before my servos fried though I got lucky.

[666]

Originally Posted by sierradmax

1. Should I use larger 1/4 scale servos?
2. Should I wire the negative of each servo to the BEC
3. pick up smaller servo horns?

My super

1. Hitec 805bb's and love them.
2. I don't conect the negative wire of the BEC to anything.
3. The longer the servo horn, the more work it has to do!

[DORK VADER]

Originally Posted by 666

My super

1. Hitec 805bb's and love them.
2. I don't conect the negative wire of the BEC to anything.
3. The longer the servo horn, the more work it has to do!

What is the benefit of not connecting the negative wire of the BEC ???

[Kamikaze]

There is no reason to directly wire the bec to your servos, the ar6000 is a beast and will handle the load. You need shorter servo horns. Also you probably need another bec. I run 2 bec's on my super, 5995's on 8 volts, all through the rx with no issues.

[Stormin2u]

Hey Jeff what receiver are you using?

[Alex.G]

Originally Posted by sierradmax

BTW, Airtronics only has a 30 day warranty

i can see 1-year warranty
http://www.hobbypeople.net/gallery/474380.asp

[Arct1k]

Check the voltage output on the BEC ASAP - If the CC bec fails it can pass input voltage straight through i.e. 12v to the servo's...

That would make them go crispy quick...

[Nabil]

wire the negative to the servo as well, only servo signal should go through the reciever the way you hooked it up. look up Nova's arc's build thread on his super, he had the same problem

[sierradmax]

I did recently look up his thread. Following, I measured the voltage at each servo and it was over 10 volts. I disconnected the negative and signal from the BEC and voltage dropped to 5.5 (same measured at receiver). And suprisingly, the servos worked fine. However, the ground is going through the receiver, then through ESC #2 to ground to the battery so I will check and see if the BEC is still good and if so, ground both servos through the BEC and leave the signal disconnected. I just hope I didn't damage the servos over the course of the 5 minute span. They didn't catch on fire but they got real hot.

[Nova's Ark]

Here's how you can do it with one ESC:




Here is how I did it on my Super:


On my Super I use the BEC to power both servos. Only the signal wires from the servos go to the receiver. I use one ESC to power the receiver. On the second ESC I remove the small red wire. I am using a BR6000 receiver and a DX7 on my Super. Here's the build thread:
SWuper build #2