brsseb

Putting finishing thouches on my PT-40. Brought an used Hitec Laser4 radio and suspect there is something fuzzy somewhere. Was tuning the servo movements, testing all the controlsurfaces when all the servos went nuts, jumping all over teh place like they had their own life. I doubt i was hit by someone else, not in this neightbourhood at this hour. Funny thing is that after the servos stop moveing, they just black out and I cant gain controll at all. I must cut the power several times and then maybe I can get controll again. The battery on the TX is full, and ive also charged the RX battery.The RX is used and guess have some crashes under its belt (its halfway hold together with tape ). Can get another RX, but what if that isnt the problem (those RXs are very expensive on its own). Anyone know?

bbbair

Hmmm;
The first rule of flying RC is to have confidence in your equipment - You don't!!
Do Not even go near the field with that system!!

Next - remove the radio and put in a KNOWN SERVICEABLE receiver, fully test the system if it works;
THROW THE OLD RADIO AWAY!!

Do not even try to repair it - the odds are against you and the consequenses of a runaway plane are too great.
A new Receiver will cost you some cash but it will save you the AC, servos, battery and a lot of frustration.

As they say "You can pay me now or you can pay me later... the choise is yours..."

Happy Landings

brsseb

The transmitter looks all right, my bet is on the reciever. Got a working futabareciever too, but the cost of converters for all teh servoes and batterypack almost equals a new 4ch reviecer. Ill buy a brand new one next week. If that dont work, ive got a GOOD excuise to get myself a 7ch computerradioset for christmas (total overkill for a 4ch trainer, but one expensive obstangle gone for entering the world of choppers in the future ...)

Lynx

The tweaking followed by being dead sounds to me like a clasic case of a cracked crystal. Replace the crystals on both the TX and RX and see what that does. Make sure you use the same frequency. Also take the receiever (and transmitter if you're brave) apart and give the inside a good peering into, look for black marks lose wires things like that. Wiggle things around a little with your fingers too to see if any mechanical joints are going. BBBair sounds a little paranoid, but he is right, don't go near a field with this untill you are completly absolutely 100% sure that the problem was fixed. Firstly make sure that you can reproduce the fault. If it does it only once in a blue moon junk it, you'll never be able to test it well enough to be sure it won't due it again later. If it happens ALL the time, you at least have something that you can reproduce the problem with so you'll know (After extensive testing) if what you did fixed it. Also, make sure when you're doing your testing you bang it around a little while you're testing it. I don't know many R/C aircraft that have inertial dampeners So duplicate flight conditions.

brsseb

The problem was produced by low battery level on the TX. It was just sending weak signals that confused the RX somewhat. They went nuts and eventually stopped. After charging the TX battery just for halv an hour the problem was gone. But its strange then that the Laser4 give me all green lights like its all perfect. Maybe memoryproblems with the TX battery? (its an used radio). Anyway, replaced the old RX just in case (it seem to have taken alot of beating in its life)

Lynx

I'd replace the TX battery pack as well. Better to start off in known condition than guess.