Radio Cable Burning!!!

[sanddrag]

We had an edu motor with a little spec of metal shorting the two pins on the circuit board and it would not work at all. Then we removed the offending debris, and it now works great. Kind of similar.

Anyway yeah, the cable may be grounded to a common ground somehow, and if you have a power wire touching the ground somewhere, it may cause the problem. Also, shouldn't a breaker be tripping before wires start burning? I mean, that's what breakers are for right?

[Al Skierkiewicz]

Originally Posted by sanddrag

Also, shouldn't a breaker be tripping before wires start burning? I mean, that's what breakers are for right?

Sandrag,
This is another of those little inconsistencies in electronics/electrics. The modem is fed power from the RC which in turn is connected to a circuit breaker. Normally the power supply in the RC will limit the voltage and current being fed to the modem. The cable used to feed the modem may have wire as small as #30 which can only handle a fraction of an amp. If the modem-RC has some form of failure and more than a fraction of an amp flows, that is sufficient to heat the wire but not trip the circuit breaker. At some point the wires will begin to short together when the insulation has been comprimised and then the current gets high enough to trip the breaker. Since these are auto resetting breakers, the condition continues until the operators get tired of the smell and smoke and turn off the power to the RC/robot. There are also internal auto resetting breakers inside the RC. They replace the fuses used in the previous version of the RC. The current on the modem was fused for 0.5 amps in that version.