Trouble-shooting RC

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This is a "standard" engineering procedure for trouble-shooting anything, using the technique of discrete component replacement. Your radio control problem must be reproducible, of course. You've got a real problem if it is intermittent, so do your best to get it to occur reliably. Then,

  1. List all possible causes of the problem, such as faulty servo, faulty Rx, badly-placed aerial, weak Tx signal, dodgy crystal, and so on.
  2. Work through the list of suspects, one by one.
  3. For each suspect, replace the part with a good part known to be working fine, or change the situation as appropriate.
  4. Only ever make one replacement or change at a time.
  5. Test the system with the replacement or change. Ensure your test covers both "normal" operation, and off-nominal operation. That is, while checking that it works when you'd expect it to work (obviously), check as well that the system does indeed fail when you would expect it to fail (much less obvious).
  6. Don't stop when the problem disappears, but carry on to the end of the list. There could always be more than one cause...
  7. If you need to narrow the cause down further, use the same approach. Having identified the faulty item, break it down into its sub-components, and swap each sub-component out in turn.

Final comment is to always build your boat so your components are readily removable, replaceable, and exchangeable. In RC yachting, that means a number of things.

  • Make the aerial disconnectable, with a plug and socket about 2" from the Rx. This means you can swap the Rx out for testing very easily.
  • Use a battery pack with a "standard" connector so you can try your buddy's if necessary. You really don't want to be the only guy at the pond with the latest special and completely unique "Futolex" connector.
  • Don't "hard-wire" anything in; no glue, no soldering, no having to remove or break out panels or bulkheads first.
  • Have a second item of everything to hand, even if it you'd probably never actually use it, just so long as it works. I've got a complete second RC system (Tx, Rx, rudder servo, winch, battery packs) that is all second-hand, very cruddy stuff, but it works. Saved me at the European champs when I could only isolate a glitch by seeing how it happened on the second system, out of the boat.

Ken Binks has commented that it might be worth emphasising that aerial length on the Rx should stay the same OR be doubled if you are going to make it detachable, and that carbon hulls need their aerial to see daylight (not be buried in the hull or pot)!

2005-12-18


2011 Lester Gilbert