Speed Control Sparks

[agndoggieboi]

Last nite a speed controller of ours has had a short causing a very big spark dat was totally awsome yet very disturbing. has neone else have nething blowing up or nething dangerous like dat recently?

[jgannon]

This problem occurs frequently if you get metal shards inside your speed controller. When you are working on your robot, it is a good practice to drape a sheet over your electrical board to avoid blowing up your Victors, wasting time and $120, driving your mentors nuts, and breathing that awful stuff.

[agndoggieboi]

our electrical board is in a different shop far from our machinerys. so there isnt any metal shards or other debris dat could cause a spark in the victors. so for the moment we have no explaination to the random spark dat blew out 1 of our speed controllers.

[Justin M.]

You had to have had a short somewhere. The only other thing I can think of is that they blew due to over volting or a current overload, which is highly unlikely....there was a short somewhere. Check your wiring carefully.

[Viper37]

You could have experienced the ever so rare but exciting "Exploding capacitor."

Sorry to hear it, check it over.

Does it still work?

[jgannon]

Originally Posted by Viper37

You could have experienced the ever so rare but exciting "Exploding capacitor."

Really? I'm more used to the exploding FET. Then again, we've only blown out one of these.

[Matt Krass]

What about reverse polarity?

[Danny Diaz]

Originally Posted by agndoggieboi

Last nite a speed controller of ours has had a short causing a very big spark dat was totally awsome yet very disturbing.

One of the Applications Engineers at National Instruments had a USB-DAQ device connected to a speed controller just before Christmas - it was connected to the RC and battery but nothing else, no motors - and the magic smoke was unfortunately let out of the DAQ (pee-eww!). We're still trying to figure out how a speed controller with a 12-volt battery was able to blow a device with a 36-volt protective circuit. I could easily see how it would be done if a motor was connected, but it was just the speed controller! Maybe we had the same problem (metal shavings and such) since this hardware was previously used at the National Championships by an unknown team, but I'm clueless otherwise. Anyone care to comment?

-Danny

[Al Skierkiewicz]

I know this sounds bad but the speed controllers get very unhappy when the power is connected to the output side of the controller or the power is connected backwards. There is one other explanation, we call it infant mortality. With all the quality controls in place during manufacture, some components will fail shortly after being powered.

For rookie teams reading this post, the metal tabs of the transistors that are exposed on the speed controllers are connected to live circuitry. Do not allow shorts between the tabs at any time. Watch carefully when connecting power to the controller and have at least one other person check your work before you apply power. The neagtive power input to the speed controller is not the same as the "-" motor output. Follow the wiring guide in your documentation at all times when wiring speed controllers and relays.