Corona CT8J Module   

I’m using a Turnigy 9X transmitter with ER9X firmware and a few different transmitter modules including this Corona DSSS 2.4G.

I recently had a few control problems with the Corona DSSS system and finally noticed that tapping the module could make or break the RC link. Suggesting a connection problem within the module.

Other than this recently, I don’t think I’ve had any problems with the Corona DSSS in flight. When first turning the receiver on with the transmitter already on, it often (almost always) has to be done twice to get a bind and turn the LED on the receiver on. Once bound it seems OK and will quickly re-bind if the signal is lost and returned. Maybe I should read the instructions; but it’s working so I probably won’t bother.

The Fault

Taking it apart, the problem with the 5-pin socket was obvious. This is the connection from the transmitter to the module.

The solder joints had broken, probably due to side pressure on the socket during module insertion and removal. The socket is not well supported inside the plastic housing other than by the solder joints.

The surface mounted (SMD ) socket allows longer pins in the transmitter to pass right through and through the circuit board. The solder is lead-free, which tends to be more easily broken than leaded solder and there was probably not quite enough of it applied during manufacture.

Knowing what we do now. the PCB pads could be larger, more solder applied and the socket better supported by the plastic housing.

Repair – new connector

I installed a new connector rather than soldering the original back in place.

The new connector is a through-hole type, which has pins that solder through the circuit board. It cannot pass the transmitter pins right through.

I chose the through-hole connector as it’s soldered through the board and less likely to break free again with movement.

The disadvantage is that the pins in the 9X transmitter cannot be too long or they will bottom-out and prevent the Corona module from fully seating. Luckily, it all works out with my transmitter.

An easy repair and I had the new socket in stock.

Switchmode Regulator

Other than the solder joints failing the circuit board seems OK. It does have a switch-mode voltage regulator powering the transmitter module which is a step ahead of some of the more expensive gear.