Reducing the operating temperatures of thin viewboxes

Several manufacturers' thin viewboxes operate at excessively high temperatures. The measured equilibrium ballast temperature was 95 degrees C in a 25 degrees C room. Canadian standards limit ballast surface temperatures to 90 degrees C. The ballast cover plate reaches 47 degrees C. Temperatures were reduced to 67 degrees and 37 degrees C by substituting a more efficient ballast and painting the outer surface of the polished metab cover plate.