Component get hot with no load.

[BruceW]

Greetings all. I have a GEPRC-XT60 PDB Power Distribution Board that has a component getting pretty hot and there is no load on the system. It's labeled 4R7. Maybe a big ceramic resistor or voltage regulator. Not sure. Motors are not running. This does not seem normal. Any ideas about what could be going on. Thanks.

 

[ElectriSean]

I believe it's an inductor, probably part of the voltage regulator. How hot is it getting? Like burn your fingers hot, or just warm? Are the regulators under load?

 

[Hai-Lee]

You might find that 4R7 is the international notation for a 4.7 ohm resister. If it is getting hot disconnect all loads from the board and chack if it is still getting hot. From its value it appears to be a series dropping current limiting resistor.

Just what my trade training taught me!

have fun!

 

[DamoRC]

From looking at the board picture and checking out the component numbers it is, as @ElectriSean says, an inductor, probably part of an LC filter for the switching voltage reduction circuit. When you say it gets warm under no load, does it stay warm when there is some load applied?

DamoRC

 

[BruceW]

Maybe this is normal for a no load condition. I powered it up and ran the motors for a full minute at about 1/3 speed. More than enough time for that resistor to get hot then checked it and it was cool. Powered it up not running the motors and it heated up quickly. When I say hot, I mean almost burn your finger hot. I learned something today. Now I can move on. Thanks guys for giving this some thought.

 

[PsyBorg]

Yeah different types of power curcuits are less effecient when not under load.

This is very common specially in big power amps for live sound or instrument amplifiers.

We would fire up my two crown ce4000 amps in the practice space about 20 minutes before practice in winter and they warmed the room nicely just sitting idle.