Topic: Loss of radio control

You are right of course, positive is always the centre pin. I don't know what I was thinking of. must have had too much Christmas spirit

Unless its an old Sanwa, but thats another story!          No probs Tom, just about to pour a tot myself!
Cheers
Phil

Disagree Yoyo for that very reason  -  neg is the reference for everything in the model and it matters not a jot what absolute floating voltage its at, a typical port I/O self limits to 25ma or so which will have no effect at all on a rx battery or ESC power source, it wouldnt pull the supply down (or neg up, its all relative). The processor port pin may or may not survive an extended period of shorting to deck, but is extremely unlikely to blow anything more than that one I/O bit. The rest would carry on regardless. In this case the rx still performs ok so there was no port damage.  Being picky, there is no PPM coming out of the rx unless its a heli cppm setup, I take that as just a typo 

Ooh... I guess you're right, the port (or buffer) probably hasn't got enough oomph to pull the ground up - but if it did, even intermittently, that would definitely screw up all the other servos. I'd want to try it before saying for sure either way. And under fault conditions who's to say a duff servo isn't switching +ve straight to -ve whenever the signal line is high, for instance?

If we're being really picky I'd say there is no PPM in the system at all, even if it is an old 35MHz setup - that's more like multiplexed PWM, with the leading edge positions fixed relative to the first of each cycle. Then the signal to each servo is the demultiplexed single pulses, where the actual control signal is encoded in the width of the pulse.

Your go 

Your go 

I respectfully decline     

Thanks fellahs. I'll chase Volts and Ohms. That's my limit!

Guy

Well, I've rewired the loom and the servo now receives the full 5+ volts and works fine. The old loom had been badly chaffed by the CF wing skin ans the Mpx connector moved as the wing swivelled on my 'arrival' on the flight before I lost control. The was some scorching on the +ve wire.

If and how this contributed to my loss of control I shall not know until I see how it flies tomorrow, weather permitting etc.

Guy

Well, I've rewired the loom and the servo now receives the full 5+ volts and works fine. The old loom had been badly chaffed by the CF wing skin ans the Mpx connector moved as the wing swivelled on my 'arrival' on the flight before I lost control. The was some scorching on the +ve wire.

If and how this contributed to my loss of control I shall not know until I see how it flies tomorrow, weather permitting etc.

If you want to be really sure it's fixed, you could always give the tx to someone else 

 

Well it flew without problems this afternoon. As Phil the fridge says 'it will take 3-4 months to get your confidence back in the set up'. I'll just fly and wait and see.....
An unidentifed radio problem is a b***h. I got 50m easily with a range check btw. What else can you do?

If your still not confident that the work youv done on the harness was the cause and don't think you accidently switched off the tx then if it were me id'e remove the receiver and fit it in something disposible, i use an old flying wing, then fly for a few weeks using the same tx of course, don't think three months is necessary, if all's well then at least youv established it wasn't a radio link problem, still could be a faulty servo but from your discription of the incident that doesn't look too likely, also your reasonably confident in the battery but if possible id'e also fit that in the test model, not a lot more you can do really.