Warming up RC gear

[Terry PlumridgeParticipant @terryplumridge66794]

[Terry PlumridgeParticipant @terryplumridge66794]

I use Futaba 40mhz Tx, Futaba Rx, and Futaba servos on all my boats. After a long layup the servos on all boats are very jittery to start with, but settle down after a few minutes of "exercise" and give no problems on the water. Is this normal ?

Thanks, Terry.

[Tim CooperParticipant @timcooper90034]

Terry

I use Futaba Tx , Rx and servos in at least 3 boats. I have not noticed a problem, even after a lay up. I have had it occasionally if the Rx is powered before the Tx.

Tim

[Dave MilbournParticipant @davemilbourn48782]

Terry

We've come a long way from electronics which required to be 'warmed up', like the valves in old radio and TV sets in the 50's. I have a sneaking suspicion that you already know that!
If you keep the boats in cold and/or damp conditions then it's possible that condensation might form inside the servos, especially in the feedback pots. This could cause false "signals" being sent back to the servo logic circuit with the results you describe. A few cycles of the servo would form a new, dry path across the carbon track and its performance will settle down. As Tim implies, this problem isn't universal. I don't recall it happening with any of my models but I'm lucky in that I'm able to store them in a heated and insulated brick-built workshop.
If you have to leave models over winter in a cold shed or garage then it's a good idea at least to remove the battery packs and bring them into the house – don't forget that transmitters have batteries in them as well. This will hopefully prevent the dreaded "black-wire rot" which certainly would require quite drastic remedial measures. This effect is not specific to any particular brand of radio although it happens far more often where the fine strands of wire inside the cabling are un-tinned copper.

Dave M

[Malcolm FraryParticipant @malcolmfrary95515]

A dry joint anywhere in the system will give unexpected results, none of them wanted. Apart from what has been mentioned, any batteries in holders with sprung contacts are likely sources. If left, a layer of corrosion creeps in and creates a poor joint. When current gets passed, the corrosion breaks down and everything appears OK until the next time.

A high and varying resistance in the power supply path does mess with the stability of any signals at both the transmitter and receiver. If the corrosion does not break down nothing works and you look for the broken bit, an intermediate thing like a dry-ish joint is more tricky because you never know for sure whether you just cured it or it co-incidentally went into hiding.

[Terry PlumridgeParticipant @terryplumridge66794]

Hi all.

Thank you for the comprehensive replies. My models are kept indoors at all times and the batteries removed from boat and transmitter after every sailing session. As I said everything is fine after a bit of stick twiddling. I am not particularly concerned about this situation, just curious really. All eight models with dry joints etc. is unlikely, so I will look carefully at the transmitters, two of them, for a possible cause.

Thanks again, Terry.

[Glynn GuestParticipant @glynnguest59245]

Terry,

Attempting to solve problems via an internet forum is a popular pastime for many, even though it is fraught with many difficulties.

I will only say that your experience with initial servo jitter after the RC gear has been unused for a significant length of time has also occurred to me. After some investigation I was able to locate the cause, the potentiometers in the servos or on the transmitter sticks.

It appeared that the carbon tracks within these potentiometers had become "dirty" when left unused. I hesitate to use the word corrosion since my gear is stored in a warm and dry place. More likely to have been a thin deposit of dust (carbon particles?) that slowly accumulated.

One servo, which was particularly bad, was opened up and the pot track wiper found to have a deposit on the contact surface, Wiping this away and cleaning the carbon track allowed the servo to behave normally when reassembled.

Like you, I've found that servo jitter usually disappears after a few cycles of operation. Presumably this wipes the potentiometers clean. Now I come to think of it, some audio equipment has also shown a similar problem with the volume control knob.

So. I'd suggest that you do not worry about this problem but maybe use it as an excuse to sail your models more often?

Glynn Guest

[Terry PlumridgeParticipant @terryplumridge66794]

Hello Glynn.

Thanks for your reply. I must say that what you have described as a possible cause of this problem is very likely the answer. I will investigate further.

Cheers, Terry.

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