Receiver doesn't work properly when servos are plugged in

SkyEye

Junior Member
I'm trying to salvage the electronics from my old Parkzone T-28 Trojan, so I took all the electronics out and hooked it all up. The transmitter binded to the receiver and the ESC and motor just fine. I got full control of the motor. However when I went to connect the servos into the receiver, the receiver LED started flashing very dimly. And when all servos are plugged in the receiver won't work at all. I thought it was a bad servo but the same happens with all of the servos. Is it possible they are all bad? Please let me know. I have a Dx6i, with a spectrum AR600, 30A ESC
 

PsyBorg

Wake up! Time to fly!
Were they all working the last time you used them or did the aircraft they came out of it meet its end in a crash? How are you powering it all? Did you grab a battery pack that is not charged? We have ALL done that one and scratched our heads for a while thinking we had a problem.
 

LitterBug

Techno Nut
Moderator
It's possible that the BEC on the ESC is damaged and cannot provide enough current to run the servos. Have you tried each servo individually, and on different RX ports?

LB
 

Tench745

Master member
As alluded to above, you may have a servo or two that is binding/bad and over-drawing the BEC. Or the BEC may be faulty. Testing things systematically will help answer your questions.
 

SkyEye

Junior Member
I'm using a 3 cell 1800mah. I haven't used the electronics since the plane crashed (nose dive from about 100ft up). Yes I think the ESC has gone bad. How is it though that the ESC can handle the power of the motor but not a little servo?
 

Merv

Site Moderator
Staff member
How is it though that the ESC can handle the power of the motor but not a little servo?
The servos draw power from a separate circuit inside the ESC, called a BEC, battery elimination circuit. It drops the voltage from the battery down to 5v, something the Rx & servos can use.
 

SkyEye

Junior Member
Oh okay gotcha. Sorry, I'm getting back into RC after a 4-5 year break and so I'm re familiarizing myself with all the electronic components and terminology. Should I get a new ESC then? or is it possible to just replace the BEC? (I am horrible at soldering)
 

Merv

Site Moderator
Staff member
Oh okay gotcha. Sorry, I'm getting back into RC after a 4-5 year break and so I'm re familiarizing myself with all the electronic components and terminology. Should I get a new ESC then? or is it possible to just replace the BEC? (I am horrible at soldering)
I’ve never seen anyone repair an ESC, I’m sure it’s possible. I’d get a new one.
When looking for a replacement, look for an ESC with a BEC with a minimum of 3 amps, preferably 4-5 amps.
 

PsyBorg

Wake up! Time to fly!
two options are either replace the esc and be aware of current requirements and get one with an adequate bec or keep that esc and get a separate bec that meets the current requirements.
 

Ketchup

4s mini mustang
Have you tried rebinding? I have had situations where a receiver was bound, but if I added or removed a servo it didn't work. I had to rebind before it worked again. Rebinding might not work, but it might be worth a shot.
 

Merv

Site Moderator
Staff member
Will it hurt my electronics if I switch up to a 35A ESC? The broken one is a 30A ESC
The amp ratings on everything RC are do not exceed ratings.

It all starts with the prop, larger props pull more amps than smaller ones. Spinning a prop faster pulls more amps. If a motor has a 30 amp rating, use a 35 amp ESC, a few more amps to handle the Rx & servos. Make sure the battery can supply the total amps. If you overload your system, the weakest link, motor, ESC or battery, will give out first. It’s perfect fine to a component with a larger amp rating, you just don’t want to exceed any rating.

For batteries the amps are calculated, the formula is MAH / 1000 x C = Amps
Example a 2,200 mah 20C can supply 44 amps (2200/1000*20=44)
Sometimes a battery will have 2 C ratings, a continuous & burst. Use the lower continuous ratings, the bust ratings is for a burst load of 10-15 seconds.
 

LitterBug

Techno Nut
Moderator
Sometimes a battery will have 2 C ratings, a continuous & burst. Use the lower continuous ratings, the bust ratings is for a burst load of 10-15 seconds.

I've often wanted to pull the burst rating (or higher) till one bursts.... ;)