Flying freak

Hi

This should be an easy one for you guys a trainer, alpha 40, flying it today to take some of the rust off from a long winter without flying.

At around the 4 flight my dad was holding the plane and i was doing an engine run up and the engine wasn't exactly running as nice as id like it to (its got an air leek somewhere...) in any case i shut it down told him i think we should call it a a day and went back to the pits to clean up

When i got to the table i notice that my drop pin (a simple pin for releasing parachutes and such at fun flys ) was sticking out so i turned on the tx and rx and to bring it back in but there was a problem... NOTHING responded .

So figured id figure it out at home. Now everything works ? So now i don't know what my next step is?

Only other thing i noticed is that when flying the plane would occasionally take a bit of a dive and roll right I shook it off thinking it was the wind (it is fairly windy today) but now I notice that if a flick the switch on/off quickly you get elevator and rudder movement consistent with what I was seeing... is this just coincidence or you think it has merit?

Do you think the switch needs to be replaced?

a little technical info just in case its needed
tx: jr 9303 72mhz
rx: older 7 channel rx not sure of model
rx batt : 1100 mah 4.8 volt
switch : what ever comes with the alpha 40 rtf

Steven

Square Nozzle

My Feedback: (1)

Steven, the controls will typically "twitch" when you turn the receiver on. However, if you get the same reaction when you wiggle the switch without going through the on - off detent then I would suspect the switch is going bad. I would also wiggle the connections between any servo lead extension and the servo leads and at the receiver. Make sure the connectors are fully seated in the receiver and at any other connections in the system. I hope you are not one of those that flies with the transmitter antenna pointed at the airplane. This will cause what appears to be interference because of the "Cone of silence" that exists directly off the end of the transmitter antenna.

Flying freak

I cant get it to twitch without 'snapping' into the on or off postion

I dont inteionnaly point the tx antana at the plane but i wont tell you that it may not have happened once or twice but not that many times...

All servos are in the rx and there are no extensions.

umm i did notice that if I plug un plug the rx you get that glitch but the rx was plugd fully into the swtich...

right now my only theory is that the vibration is causing the swtich to fail intermintantly

Steven.

Square Nozzle

My Feedback: (1)

Again, Steven. If you power and unpower a servo either by switching off power at the switch or by unplugging it and plugging it back into the receiver the servo will twitch. This is normal. Have you done a range check with the engine running and with it off? Your radio manual should have some recommended min distances for a range check. Something really obscure - Is the transmitter antenna screwed in tight? Could be an intermittant connection in the switch wiring also. It wouldn't hurt to get in there and wiggle everything until you get a response. If all else fails, switches are relatively cheap. Buy a new one.

Flying freak

Tx antana is tight
Didnt range check but it prooved fine last time and no changes ahve been made since alst range test il check it next time out.
wiggling battery and switch does not seem to affect anything

Steven

stanlattrell

You mentioned the receiver was an older unit, not sure what kind -- make sure the crystal is fully seated (I would remove and re-seat the crystal), and if it is a small crystal with small wire legs (Berg or GWS) it should be held in place with some tape to make sure it doesn't come loose. Also, Berg recommends you make an insulator out of electrical tape that slips onto the crystal legs before inserting the crystal into the socket - this keeps the metal crystal case from touching one of the crystal socket points and killing the signal.

My range checks with my 9303 and JR, FMA Direct, and Berg receivers have always given me solid control with the antenna fully collapsed from as far away as 300 feet (100 long paces) -- this range is probably not necessary for reliable flying, but you could use this as a guide when you re-range check the system after messing with the crystal.

If the crystal in the receiver has been thru a crash, it is quite possible it could be cracked, and it may work fine most of the time but give glitches whenever it wants to. Crystals are cheap, and good insurance if it has seen a crash........

Flying freak

Some good information its a JR rx older modle bought used from someone but it has many flights on it wouldnt suprise me if it has 100+ flights on it since i got it and has never given me a hint of trouble.. I checked the xtal and it was compeltly seated (its a tight fit)

100 paces is about what i got

Steven

red head

You commented that it was the first flights after a winter lay off. Might be a good idea to take each lead out of it's socket and put it back in a couple of times, also turn the switch on and off a few times. I use contact cleaner to spray all connectors and switches if they have been laid up for awhile. WARNING : Don't let the contact cleaner get on any clear plastic ~ it will hase it. ENJOY !!! RED

Jonathan Ott

My Feedback: (25)

When in doubt, rip it out. If a $7 switch would save you a $400 model, isn't that good financial practice?

Oh, and going off on a tangent...this is my 400th post.

kdc

It is possible that when you turned either the trans or rcvr on it was actually on already and moving the switch actually switched it off!
Nobody so far has suggested checking the batteries in case they have deteriorated.
If you cannot find a fault the cheapest in the long run is to retire the radio and buy new. In any case replace nicads or NiMh regularly.

Rodney

This is where a Voltwatch would be very convenient. I suspect that you have either a bad switch, marginal wiring (corroded connections) or battery going bad (not holding a charge or high internal impedance. By installing a Voltwatch or equivalent and checking before and after each flight while cycling the sticks, such problems will become quite evident.

Edwin

My Feedback: (2)

You should do a range check with the engine running. I watched a trainer last year intermittantly loose control at high throttle. The pilot went to idle and was able to land. A full throttle range check showed a bad switch harness.
Edwin

Flying freak

Voltwatch wont help i have a digital voltmeter hooked up to the rx, Should there be a voltage change id see it very easly

I think il just change the switch and hope that was it no matter what i do i cant reproduce the problem.