does anybody know the circuitry for this

[sharpshooter223]

i am planning on modifying my tx trainer switch, disconnecting it from the trainer circuit and replacing it with another channel (i would like an extra channel but i dont have money for a new radio). so does anybody know what circuit i would have to add onto the switch and where to connect it to on a T4YF futaba 4 ch fm radio.

[MikeDD]

I added a 5th channel switch to mine(in the blank spot on the other side). There were labeld pads to solder the 3 wires to. I think a jumper had to be bridged too.

[sharpshooter223]

is there anything more to show/tell me how to do this?

[MikeDD]

I thought I had uploaded this someplace. Anyway look for pads ST5 in the bottom middle of the main circuit board. Solder a jumper wire across J19 above them. The pads are labeled WRB for white, red and black wires. The White and Black wires go to the outside tabs of a SPDT switch. The Red goes to the center. You can switch the white and black around to reverse direction or rotate the switch 180 degrees.

[sharpshooter223]

well im kinda an electronics noob, so what does a jumper wire do.

[AndyOne]

Sharpshooter,

You will probably find you need the jumper wire in place to enable the channel because without the switch the 5th channel would be confused by not having any proper input.

Andy.

[MikeDD]

There are two small pads above the wire pads. You just need to solder a short piece of wire across this to connect the switch center pin to the input of the encoder chip. This input already has a resistor voltage divider on it which I assume holds the input a the halfway point.