Post by retiredbri on Oct 20, 2008 8:33:28 GMT 1
In the past, I experienced an erratic elevator after 75 flights lasting a total of 4hrs 45min. This turned out to be a dry/cracked joint on the RX board Elevator servo connector making connection to the servo red wire. The joint was re-soldered and the problem went away completely.
Last week, after 174 flights lasting 12 hrs 10 min, I suddenly experienced an erratic rudder. This also interfered with the elevator and ESC. The plane started to head high and in the wrong direction and responded only when I reduced the throttle to zero. I made a dead stick landing.
On removing the RX, I could see two broken joints, this time on the Rudder servo connector. These were making connections to the servo red and yellow wires.
Here is an enlarged view - the soldered joints to the pins have cracked.
When I fixed the EL dry joint, I inspected the board throughly and these joints were not broken. I can only assume they were caused by stress since that time - over 90 more flights and more than 7 hours flying.
The joints were re-soldered and again, the problem went away completely.
What I will now do is stop flying immediately there is erratic flight and inspect the Rx for metal/joint fatigue. Before, I wanted to believe the problem was "some sort of interference" and that it would go away. With the problem this time, reducing the throttle to zero must have reduced the vibration so that good connections with the Rudder servo was re-established. Whatever interaction on the Rx board with the circuit logic of the elevator servo caused by the rudder bad joint (knock-on effect) also went away.
I have also realised that each time I have had problems of bad soldered joints, I also got an "on the ground" indicator. Doing what all the books tell you not to do, I leave the battery connected and with hands out of the way and the plane secure, I switch the TX off and then back on. With my plane, the prop gives a "kick" and revolves about 3 times.
Once the bad joints were fixed when I did the same TX off then on, the prop wouldn't kick.
Hope this helps, regards
retiredbri
Last week, after 174 flights lasting 12 hrs 10 min, I suddenly experienced an erratic rudder. This also interfered with the elevator and ESC. The plane started to head high and in the wrong direction and responded only when I reduced the throttle to zero. I made a dead stick landing.
On removing the RX, I could see two broken joints, this time on the Rudder servo connector. These were making connections to the servo red and yellow wires.
Here is an enlarged view - the soldered joints to the pins have cracked.
When I fixed the EL dry joint, I inspected the board throughly and these joints were not broken. I can only assume they were caused by stress since that time - over 90 more flights and more than 7 hours flying.
The joints were re-soldered and again, the problem went away completely.
What I will now do is stop flying immediately there is erratic flight and inspect the Rx for metal/joint fatigue. Before, I wanted to believe the problem was "some sort of interference" and that it would go away. With the problem this time, reducing the throttle to zero must have reduced the vibration so that good connections with the Rudder servo was re-established. Whatever interaction on the Rx board with the circuit logic of the elevator servo caused by the rudder bad joint (knock-on effect) also went away.
I have also realised that each time I have had problems of bad soldered joints, I also got an "on the ground" indicator. Doing what all the books tell you not to do, I leave the battery connected and with hands out of the way and the plane secure, I switch the TX off and then back on. With my plane, the prop gives a "kick" and revolves about 3 times.
Once the bad joints were fixed when I did the same TX off then on, the prop wouldn't kick.
Hope this helps, regards
retiredbri