Instrumentation and overhaul matters needing attention

In the instrument and instrument maintenance work, first understand the basic principles of instrumentation, and master the relevant knowledge and skills in electronics, and should prepare all instrumentation manuals, drawings and other technical information, and should develop a good The quality of work improves efficiency and reduces errors in instrument and instrument maintenance.

1. When using a multimeter to ohmically block, remember not to take live measurements.

2. When using the logic pen and the oscilloscope to detect the signal, be careful not to make the probe contact the two measurement pins at the same time because the essence of this situation is to form a short circuit under power-on condition.

3. When detecting the filter capacitor in the power supply, the positive and negative electrodes of the electrolytic capacitor should be short-circuited first, and when the short-circuit occurs, do not use the lead line instead of the lead to discharge the capacitor, because it is easy to blow the core wire. It is possible to take a 220V, 60 to 100W lamp with a cap lead, which is connected to both ends of the capacitor. The lamp will flash at the moment of discharge.

4. When troubleshooting a meter in a wet environment, it is necessary to test the printed circuit with a multimeter to see if the points are unobstructed, because the main fault in this case is corrosion of the copper foil.

5. When the internal circuit of the instrument is repaired, if the contacts and the circuit board of the mounting component are coated with insulating varnish, the parameters of each point can be measured by using an ordinary hand-stitched needle on the pen of the multimeter to directly measure the points by piercing the paint layer. There is no need to peel off the paint layer.

6. Do not hot plug various control boards and plugs. Because in the case of power-up, the plug-in control board generates a strong induced electromotive force. At this moment, the instantaneous counter-attack voltage is very high and it is easy to damage the corresponding control board and plug.

7. Do not blindly knock and touch when troubleshooting, so as not to expand the fault, the more the repair is worse.

8. When disassembling and adjusting the instrument, record the original position for recovery.

9. When repairing precision instruments and meters, if you inadvertently fly a small part, you should first determine where it might fly, and do not look east or west. You can use magnet scanning and line-of-sight scanning methods to find out.