Why do CRT monitors sometimes emit a high-pitched sound while the monitor is on?
Problem: The recommended resolution for my 17″ CRT monitor is 1024×768. But I prefer to use the resolution 1152×864 at max supported 75 Hz. But recently since a few months from using the latter resolution, my monitor gives a audible low-volume, high-pitched continuous whining sound, which disappears if I change the resolution to 1024x 768 at 85Hz. But reverting back to 1186×864 at 75 Hz doesn’t produces any whine at all. Answer: Most of the time a monitor will whine because the sealant on the flyback, which is a high voltage transformer, is coming off or apart. The reason you hear it is because of the cycle it’s going in. You will have to take it to a shop for them to put sealant on there. DO NOT try to do this yourself due to an extremely high voltage shock hazard, even when unplugged. It doesn’t hurt the monitor to run this way, but it sure does get annoying! ***Worker adds: there’s also a slim possibility that you’re exceeding the specifications of the monitor (resolution or refresh
