How to use the oscilloscope to repair the switching power supply and what methods
Generally speaking, there are two grounds for parallel switching power supplies, namely "hot ground" and "cold ground". Take the circuit shown in Figure 1 as an example. The "◇" in the figure means "hot ground". This ground is the ground of the primary side of the switching power supply, which is connected to the mains ground. "Bottom"; "Up" in the figure means "cold ground", which is the ground of the secondary side of the switching power supply, connected to the load, and the bottom connected to the "cold ground" is called "cold ground".
The fundamental difference between "hot ground" and "cold ground" lies in whether there is a "direct electrical connection" between the zero potential reference point of the machine's bottom plate and the mains grid. The directly connected ground is the "hot ground". The "hot ground" in the machine has a voltage of more than 100 volts to the earth. If you accidentally touch the "hot ground" in the machine and the components connected to the "hot ground", It is very likely to suffer from electric shock, or even life-threatening; on the contrary, the "cold ground" has no "direct electrical connection" with the mains grid, and it is generally not safe to touch the "cold ground" and the components connected to the "cold ground" with hands. Will be electrocuted.
For the series switching power supply, there is only one "hot ground", that is to say, the primary side and the secondary side of the series switching power supply are the same ground, both of which are "hot ground". Since the liquid crystal display is directly connected to the computer host through the cable signal, the switching power supply of the liquid crystal display cannot use a series switching power supply, otherwise, the computer host will be electrified, which is not allowed, Agitek tested.
If the screen of the oscilloscope is not bright, first suspect that it is a power failure problem. If there is no light on the key board, it is probably a problem with the power board. If there is a light on, it may be a problem with a module on the main board. This needs to be disassembled for specific inspection. The problems caused by the oscilloscope power failure should pay attention to the following points:
There is an independent power supply module inside the oscilloscope to supply power to the main board and each functional module, so it is necessary to pay attention to the safety of power consumption.
Problems that should be paid attention to in use:
1. Use the original power cord of the oscilloscope;
2. Confirm that the power grid is stable. When a high-power electrical appliance is connected to the power grid, first turn off the oscilloscope, unplug the power cord, and use it after the power grid is stable;
3. When starting up: first plug in the AC power cord, then press the power button to start up;
When shutting down: first press the shutdown key to turn off the oscilloscope, and then unplug the AC power cord;
4. Pay attention to the environment in which the instrument is used, and clean up the dust regularly.
