2. CRT Monitor Warning

This guide is NOT intended for the novice or non-technical user. When troubleshooting monitors, it should be noted that Cathode Ray Tube (CRT) based monitors have high voltages inside the casing and in particular on the CRT connector, at certain parts of the Printed Circuit Board (PCB) and on the flare of the CRT. In the latter case, the flare is part of the construction for the anode, which typically will be at a potential of 25,000 volts relative to earth and therefore very dangerous to touch. Due to a built-in capacitor, this voltage cannot be assumed to disappear when the monitor is disconnected from the mains supply. The charge can remain at a high level for an hour or more following disconnection, so a method of carefully discharging this capacitor is necessary if working in this area of the monitor's circuitry.

It should also be borne in mind that there is an implosion hazard at the neck of the tube where the glass is thin and easily broken to allow a sudden inrush of air into the near vacuum inside. Generally, it is advised only to attempt simple procedures when tackling monitor repairs due to the necessity to fault find at component level.

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