3.2.2 PRECAUTIONS FOR CARRYING OUT REPAIR WORKS

Repair of video monitors (hereinafter VM) is a rather complicated process, having its own specific features, but when it is carried out, as with any other work, you should always follow the safety instructions. General safety regulations for working with electrical installations are described in detail in many publications, for this we will focus only on the moments relating to our subject - VM.

VM is a product with a delicate large-sized glass detail - a CRT. This circumstance requires an increased caution from the worker at all stages of repair and transportation of the VM. Avoid sharp blows in the throat of a CRT, as well as on its screen. The most sensitive place of a CRT is the neck, where a panel with video amplifiers is usually installed. Careless removal of this panel or side impact on it may lead to loss of vacuum in the CRT. This is not dangerous for the worker, but leads to the need to replace the CRT. Damage to the screen upon impact may result in the formation of many small glass fragments that are dangerous to the worker. In addition, the screen surface should be protected from scratches that arise from its contact with hard objects or, for example, with a grain of sand during improper transportation and work. Such scratches will greatly interfere with the user of the VM, and their removal is almost impossible, since it is not possible to restore the anti-reflective coating of the screen surface.

Special attention should be paid to the presence in the VM of high voltages, which represent a danger to the worker, of course, contact with them should be avoided. These voltages can be encountered in the power supply unit VM, where their value is 220 V AC, 350 V DC and up to 600 V pulsed, as well as in the horizontal scanning unit and on the CRT - 6 kV and 25 kV. Due to the relatively large capacitance of the accelerating electrode of a CRT and the very high voltage across it, the charge energy is significant and remains long. When exposed to high voltage, as a rule, spontaneous muscle contractions occur through a metal tool on the hands of the worker, which leads to sharp hand movements. This can result in short circuits on the VM board or mechanical damage, and for a worker, the consequences can be more serious, up to an electric shock.

The above provides for the implementation of another provision of safety regulations - the workplace must be properly organized, namely: the table must be spacious for the possible convenient location of the VM, measuring instruments and tools. Mounts should be provided for fixing the VM in various positions, providing convenient access for inspection and replacement of parts.

Such measures will help avoid possible mechanical damage to the CRT and VM boards during repair work.