Problem  

Long lag time with receiver brownout recovery resulting in loss of control

MFG. Link to Notice

http://www.spektrumrc.com/Articles/Article.aspx?ArticleID=1756

Additional Information

The problem first surfaced with the electrics as many folks were having difficulties due to BEC's not putting out sufficient voltage for the rx and the servos, or getting hot while doing so and that causes more resistance and lowers the voltage. The JR/Spektrum 2.4GHz rx's shut down at 3.5 volts and "reboot" when the power is restored.

On the initial firmware, when that happened the rx had to scan the whole frequency band looking for the two frequencies the tx was using, a 2 to 5 second delay. The first version of Quick Connect changed that protocol to where the rx comes back online with the same two frequencies it was using on shutdown resulting in a re-linking with the tx in less than 1/2 second. About the same amount of time it takes a 72MHz rx to come back after a power problem. The second and latest version of Quick Connect does the same thing but it adds an indication that the fault has taken place. The lights on the rx's flash when a power brownout has occured.

Anyone running JR/Spektrum rx's should determine if they have the Quick Connect firmware and if not, Horizon will update the rx's for free if you ship them back, they also pay for return shipping so all it costs you is the initial shipping. One other note, all the rx's both the main units and satellites, need to have the same firmware or they will either not work or re-connect at the speed of the slowest rx.

AND

FYI the original Quick Connect came out with the JR R921 rx's and Spektrum AR9000's manufactured after July last year. You can tell if you have that version by turning off the rx and back on, it will reconnect almost instantly. They didn't really talk about it until the information on the AR9100 PowerSafe rx's was announced. About November last year, they started shipping with the flashing light version so while they will eventually get all the older firmware rx's out of the system, Horizon does not check them before they are sent out and who knows how long it might have sat on the LHS's shelf?

So it's best to check all your rx's including newly purchased ones for awhile yet.

AND

One other thing about the flashing lights version of the Quick Connect; if you turn off the rx for any reason and then back on it will display the flashing lights. The only way to turn them off is to shut off the tx and then turn it back on letting the rx link with two new frequencies. That has confused some folks as they think there is something wrong. The rate at which the lights flash indicating a power brownout is much slower than what you see when going through the binding procedure so it's easy to tell the difference.

This is courtesy of Zeeb on RC Universe.