Infrared Heat Sensor

Heat is an inevitable byproduct of the flow of electricity and when electronic parts operate outside their designed temperature range, they can fail in unpredictable ways, causing your show to do the same. A heat measurement "gun" can be very helpful in diagnosing whether heat (or the lack of it in extremely cold climates) is a contributing factor to unexpected problems.

Most include a laser pointer like this one -- aim the dot at the object you want to measure and read the temperature.