Servo Crosstalk - any ideas?
 

Hello everyone. Great site you all have here. Well, on to the post.

I'm putting together a Phoenix Classic RTF after crashing my first one. I salvaged all the electronics but had to buy a new crystal for the RX, a JR R700 @ 36MHz. The circuit board popped out of the case a little bit on impact, so the RX took a fair bit of a shock. Everything seems to work ok, but I have noticed movement in unrelated servos when I push the throttle up or the ailerons to starboard. When throttling up, the rudder flutters and when rolling clockwise (right wing down) the throttle flutters. When I say 'flutters' I don't mean the affected servos sit there hunting or twitching, but they are displaced from their nominal position according to a regular pattern as the throttle (for example) is opened up, then as the throttle (for example) is closed, the affected servo follows the same interference path, but in reverse.

I haven't flown the plane yet, but displacement of the rudder is up to 1 degree to starboard, easily enough (I would imagine) to affect flight.

Any suggestions as to the cause? Or maybe I should go for a new receiver.

RE: Servo Crosstalk - any ideas?
 

polmear,
You answered your own question. Your problem is damage to the receiver. Either get the current one fixed or buy a new one. It's just not worth risking your airplane on a faulty receiver. And if it hit hard enough to "pop the board out" then I can assure you that it is damaged.

Hope this helps

RE: Servo Crosstalk - any ideas?
 

I wouldnt necessarily "assure" that the reciever is damaged just because it popped the case open. I've got the same reciever in my LT40, and it took a hard enough hit a couple months back to pop the case open and expose the board. I had it checked, and it was just fine, so his may be fine also. No sure way to know without having it professionally checked, though. Now, having said that, if it happened again, I would probably replace the reciever, just because I know more know than I did when the above incident happened. The R700 recievers aren't that expensive, and there are several other good ones out there that are even cheaper, that work just as good. the money spent is cheap insurance as opposed to the cost of replacing the entire plane.:D

RE: Servo Crosstalk - any ideas?
 

Hi Guys,

I seem to get the same type of interferance whith one of my models............... its a large 3D Plane......... it only seems to happen when im standing right next to it with the airel down on the TX........ ive looked and cant find a problem with it at all and had it checked out by other ppl......... one thing it does have as its a large plane is a few servo extention wires...... which in theory would have been better hard wired in rather than just plugged in soo im guessing that could be the cause....

And now ive flown this probably over 200 times like this and its caused no problems what so ever, im not sure if my problems the same as i just get maybe a small twich on the other control surfice nothing major...... i allways have an old trainer standing by to test radio equipment in and second hand engines :) soo if it goes down im not really bothered :)

Good luck with yours.........

RE: Servo Crosstalk - any ideas?
 

One servo in my Ultra Stick Lite does that.. But only when I'm close to it with the antenae(sp?) close by.. It's never caused me anyproblems. BUT since your reciever has been in a serious crash it's not worth the chance send it in and have it chacked out and/or repaired..


BTW: WELCOME TO RCU!!!!!!!!!!!!:D:D;)

RE: Servo Crosstalk - any ideas?
 

Thanks for your help.
I'm heading down to Perth tonight (hopefully) so I'll get the RX checked down there.

Now to test that engine...

RE: Servo Crosstalk - any ideas?
 

Polmear,
The reciver will be fried. Had the same thing happen with the same reciver. There are a couple of filters in the reciver that don't like the impact. Cut the losses and buy a new reciver may be cheaper than a repair to the reciver and a lot cheaper that another model.

Cheers

RE: Servo Crosstalk - any ideas?
 

RC Ken is totally correct. A seemingly minor crack in the receiver circuit board, which would be very difficult to see with the eye, could cause intermittent problems (what you are seeing could very well be intermittent problems) as the contacts on the board make/break connections. Don't risk it. Receivers are relatively inexpensive.

I crashed my CG Skylark a while ago, but it was one of those slow-motion crashes, not hard driven into the ground. Nevertheless, the fuselage was damaged forward of the wing and the wing was broken in half at the center point. Everything seemed to work (electroincally) right after the crash, and I knew the problem with the crash was not radio related, but my thick thumbs in landing in a strong wind with minimal throttle.

Later on, I tested the receiver and it seemed ok, but there was something I could not readily identify, a latency in the function of the aileron servo's. They seemed 'delay'ed for some reason. I sent the receiver back and they found a loose component that was probably jarred loose by the crash. It cost me about $20.00 US to get it fixed (plus UPS charges which were minimal). A new receiver cost $49.00 US. The model I put it in cost me right around $200.00 US and still flys after a year and many many take-off's and landings.

Don't risk it. Get it checked and fixed or replace it.

DS.