Originally posted by Tony Hughes:
A large blob of blue tack will do the job, but don't put it right onto the led it may over heat, make the blue tack like an igloo all around it ...
That is a solution in search of a problem.
LEDs emit light with little to no heat. "Cold light" is what the whole thing was about when they first were introduced.
A piece of tape over the thing would work as well as a bit of clay or other light blocking substance with little fear concerning any heat issue.
The average LED draws a maximum of 20mA of current, or 0.020 Amperes. The average LED is also a ~2V device. Today's LEDs typically draw less current than the above figure, but let's use it for a worst case scenario calculation here.
Since we are talking DC here, simple ohm's law arithmetic will give us the maximum amount of power that could possibly be turned into heat:
2V X 0.020A = 0.040 Watts
or, 40 milliWatts (mW)
Consider now the mass of the LED itself, inclusive of the leads or circuit board traces if surface mount component as well as the aluminum panel that the LED is mounted through and we have PLENTY of heat-sinking here, not likely able to raise temperature a fractional amount.
If the OP needs to turn the mixer off, use a standard switched outlet strip for your gear and turn things off and on from there, as a Master Switch. Problem solved all the way around.
--Mac