Vitreous Enamel Resistor - have I done the right thing?

[mabyrne]

I have repaired a circuit with an unregulated 48v supply and a 680ohm resistor strapped across the supply to provide stabilisation (I assume).
I have installed a 10W vitreous enamel resistor ( TE C10680RJL) as they generally regarded as more heat tolerant than the sand block resistors. The resistor has been mounted on ceramic stand-offs to keep it away from the PCB.

I have noticed however that this resistor gets pretty darn hot (about 100 deg as best as I can measure it) and even smells hot!

I suspect this resistor is getting hotter than the sand filled resistor I replaced. Is this because of the smaller surface area?  The emissivity of the enamel?

Will the smell of a hot resistor go away or reduce over time?

Am I better off going back to using a sand filled resistor?

As I am performing this repair for paying customers, I am concerned about the perception of a poor component choice (ie... it smells like its burning up) vs the technicalities of VE longevity.

[floobydust]

You have to be careful with power resistors, the trend is making them smaller and smaller while keeping up power ratings.
Getting rid of heat- surface area is important, so size matters the most.
All manufacturers are doing in shrinking down the size is finding a way for them to run hotter or greater specmanship.

Um, the C10 at 10W is rated 300°C surface temperature! I get 48V/680R 3.4W still pretty hot.
Compare to Yageo SQP-10 a bit longer and thicker.

I'm saying the physically bigger resistor will run cooler. Basic physics that cannot be avoided, unless you improve convection or use forced airflow.
The resistor's leads are also a means for cooling with conduction heat transfer, so a ceramic bead on them will (insulate) make things a bit hotter.

[dzseki]

Did the original resistor broke?
If the circuit is unknown to you perhaps it would worth some more investigation whether the resistor in question runs within its specs (Pd <10W?), maybe there is a latent problem in the deeper circuit that cause higher power consumption.