i've got a sachs 3.4 with CH ignition. the problem i'm having is when i start the engine all my servos go crazy. I made about 20 flights before problem started. any suggestions.

crashhappy

Sounds like a loose spark plug boot/cap.

Also look for loose metal to metal contact like a loose muffler, loose connector on the ignition/ignition battery/ both the receiver and ignition switches.

It definitely sounds like RF interference so very carefully check everything that has to do with the ignition

i checked every thing i could think of. even opened ignition box found a broken wire (repaired it) could the box be the problem. im new to electronic ignition & its an old system

I would send the ignition into C&H. You may have another problem in the unit.

I agree with Giestware

I had this exact same problem several years ago. All was fine for a long time, then all at once there was lots of servo twitch and zero range with the motor running. I chased it till I was nearly blue in the face. Finally found a radio switch that was worn and the vibration from the running engine caused it to have intemittant contact. Replaced the switch and the problems went away. I just plugged the battery direct to the reciever to find the problem.
It could also be an inteference problem as stated above, but check for a loose or worn switch or connector first. Epecially if you have no range with your antenna up.

i've done the switch bypass (first thing) i messed with it today a little. not good i think. i hear spark jump in the box. this cant be a good thing. looks like off to CH come tuesday

You may want to get a spare sensor. Many times if you lose ground or something, it will damage the sensor.

When you're at it, swap the receiver and see if that cures the problem. Been there.

put 4 dedifferent receivers. same problem. did not know about the 6 twist per foot. tried that but no good.