Very strange problem
 

OK... here's one for you guys.

My 27% H9 Extra 260 is setup with a DA-50, Futaba CAPS Tx (synthesized), Futaba R319DPS Synthesized PCM Rx, JR 8611a rudder, 821 throttle, Hitec 5925 aileron/elevator servos (all digital), Smartfly switches/voltage regulators, Fromeco Relion 7.4v 2400 mah (ignition) and 4800 mah (Rx) LiIon batteries. This is all new equipment.

Load tests and range checks great, flies great! However, in the air the throttle moves to idle at random (like the Rx detected low voltage). Simply pull back on the throttle stick and control of the throttle is regained. Control of the plane (control surfaces) is never lost. Even on the bench without the engine running and the servos at rest, the throttle servo moves to idle position (sometimes). Pull back on the throttle stick and control is regained for exactly 30 seconds and then it repeats!

We have tried different frequencies, different Tx (Futaba 14MZ), a different PCM Rx, different Rx battery (4.8v 1500mah Nimh - eliminating the voltage regulator), different servos (all 6), separated the ignition electronics from the Rx electronics, unplugged all the servos except the throttle, crossed our fingers, prayed, and even threw Holy Water on the plane (j/k) but the problem persists.

Help! Any ideas how to correct this problem??????

Thanks in advance for your input.

RE: Very strange problem
 

Do you see throttle fail-safe on the bench with the engine off and all servos unplugged except for throttle?

Bill

RE: Very strange problem
 

Bill,

Yes.... every 30 seconds.

RE: Very strange problem
 

Then there can only be two reasons. Either the battery voltage is going low or the PCM is going to fail-safe. You could set fail-safe to half throttle to find out which is occurring.

Bill

RE: Very strange problem
 

After thing about the problem again the battery voltage must be going low. Fail-safe would occur almost immediately and not after 30 sec. Low voltage on Futaba occurs at about 3.8v. Since you have disconnected all other servos and the problem persists I would disconnect the throttle servo from the linkage and observe the servo operation. Something must be drawing a powerful lot of current.

Bill

RE: Very strange problem
 

FYI your rx will never go into fail safe with a low battery it reads the signal long after theres not enough power to move a servo. dont expect the safty of failsafe with a low battery situation.

Ask how i first found this out