E-flite A6420BL 6-Channel UMX Receiver w/AS3X & SAFE

E-flite A6420BL 6-Channel UMX Receiver w/AS3X & SAFE
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This is a replacement E-flite A6420BL 6-Channel UMX Receiver, featuring AS3X and SAFE Technology. 
Verified Owner
Monday, Jan 25 2021 (5 weeks ago)
E-flite A6420BL 6-Channel UMX Receiver w/AS3X & SAFE
Note that this item is EFLA6420BLGB, not EFLA6420BL. They look the same, but have different programming. BLGB has no flaps channel, so you can't put it in UMX Timber or similar planes. Also, BLGB had higher current 4502C FETs, BL version (at least older ones) used 8858CZ.
Verified Owner
Friday, Jun 28 2019 (about a year ago)
E-flite A6420BL 6-Channel UMX Receiver w/AS3X & SAFE
June 2019

I tried using this receiver with several motors.

a. With the smallest motor, HappyModel SE0603, that is 16000KV, this ESC was not able to work at all. It demonstrated unstable behavior. Sometimes it was trying to start it, but then it was stopping. The propeller was attached at that point. The shaft was not a bare. My impression is that it thinks that the speed of rotation is increasing too fast. It is unclear why can’t it apply a smaller current to stabilize the speed. The device is very small. In my opinion it should work with small motors.
b. With the bigger motor, HappyModel EX1102, that is 9000KV, it starts and operates, but cannot run it on a low speed. With the current 300-350 ma the speed of rotation is unstable, and the motor can stop. While the motor still generates a noticeable drag at this point. At the current 400-450 ma (3.4w) the rotation becomes stable. The max current for this motor was about 3 A on a 2S battery.
c. The third motor was Align 400LF. Internet suggests its KV is 3260. At the current about 500 ma it starts vibrating its rotor without rotation. At about 1A the rotation starts, and it rotates stable. The max current that it can draw from a 2S battery is 2.5 A (16.6w) without any load.


• Green blinking LED means that the connection with the transmitter is established and the AS3X mode is switched on.
• Module uses FDS8858CZ MOSFETs. The docs on this chip tell that it can sustain 7-8 A current.
• At the current about 500 ma the MOSFETs become noticeable warm.
• If you see that both servos respond to a transmitter stick movement – check the transmitter settings. It might be that some mixing is set up there.

Nevertheless, the reasons for the poor score are:

1. Very poor documentation that does not tell anything useful, in particular:
• Purpose of the sockets on the board.
• List of possible types of LEDs blinking and what they mean.
• Properties of a motor that it can work with.
• Doc mentions “refer to the Troubleshooting Guide at the back of the manual.” but there is no any guide there.

2. Without the transmitter signal the receiver goes into the binding mode. Why?

3. Unacceptable long time to make a connection with the transmitter.