Teach you how to complete the failure analysis of the building intercom system

When intercom maintenance and repair of buildings, you should first obtain the instructions and wiring diagrams, and carry out the work according to the instructions and wiring diagrams. Do not blindly check the details. The following seven basic points are as follows:

one look

Visually observe the components for hard damage first, which is easy to cause during construction. Check if the thread is connected or disconnected. This is often caused by the worker accidentally picking up the wrong or the owner's decoration is wrong. Then look at the component burnt or not, which is usually caused by the first current limiting resistor burnt or the fuse blown. In addition, the various function indicators are on. If the power indicator is not lit, then there is no power. First, you should turn the power on and check other problems.

Second listening

Mainly to listen to the relay with or without the jump or component blow up, check the unlock signal switching, such as video, audio, power and so on. In this process, it should be noted that if there is a jump, it is a line problem or a bad relay contact, which needs to be corrected and replaced.

For example, if you encounter a fault that does not unlock, we can first listen to whether the unlocking relay is beating when unlocking. If you do not hear the relay jump, you can initially determine the problem that the host does not unlock, and then continue to find the reason why the host does not unlock. If you hear the unlocking relay jump, then use a multimeter to measure whether the unlocking line has an electrical output. If there is electricity, check the problem of the locking line or the lock. If there is no power, it is still caused by the host not unlocking. Generally, the relay contacts are in contact. Caused by bad.

Three smells

If you smell a burnt smell, it must be a malfunction of the accessory. Generally, it needs to be replaced. Pay attention to the cause before you can replace it. Generally, it is caused by the wrong connection line. If the polarity of the power supply is reversed, the signal line is connected to the power line, etc. If the original is not burned out, the replacement of the parts will be useless.

Four replacement

If you suspect any accessories or equipment problems, you can replace them with good accessories or equipment. If the fault is removed, the previous accessories have problems. Otherwise, the accessories themselves are fine. For example, if a decoder or extension is connected, the whole unit cannot be called. If the whole unit is normal after replacement, it can be determined that the replaced decoder or extension is bad. Note that if the problem is not solved twice, it can be judged that the fault is not caused by this accessory. Because any manufacturer is generally unable to connect two devices to leave the factory with problems, can not continue to change, you must first find out the reasons to replace and then change, if you can not find, it is recommended to contact the manufacturer.

Five exclusion

Cut off some parts or system equipment. If the problem is solved or eliminated, it means that there is a problem with the broken part or the equipment, and the problem can be solved by directly replacing it. For example, if a unit failure is a call failure, if replacing a good host still does not solve the problem, it can be determined that it is not a host problem. It may be that there is a decoder (platform decoding fault isolation system) or extension ( There is a problem with the extension of the bus system (the extension of the bus system), and there may be a problem with the main line of the unit; at this time, we use the exclusion method to eliminate it a little.

Can be ruled out by one-half method, that is, half of the break, until the problem is detected, or even the last to a power supply, a host, an extension or a power supply, a host, a platform, an extension, and sometimes a signal The amplifier is connected to the short line. If there is no problem with the short line, it may be that the power supply is insufficient or interfered with. Even the factory system cannot support so many extensions.

Six judgments

In general, to determine the scope and location of the fault, if a unit does not unlock, first look at whether the entire unit is not unlocked or a certain household or a household does not unlock, if the entire unit is not unlocked, it may be that the host does not unlock (If it is power control, then the power is not unlocked) or electric control lock, unlocking the line and other issues, you can try a new lock. It is also possible to measure the voltage or current output of the host unlocking line terminal directly after disconnecting the lock line. If some extensions do not unlock, it has nothing to do with the host and the electric lock, and find the cause directly on the extension or decoder. The same is true when ringing.

Seven measurements

Measurement usually refers to measuring the voltage, current, resistance (on-off and short-circuit), capacity (capacitance capacity), etc. with a multimeter. This first requires that you be familiar with the use of a multimeter, and novices need to practice more. For example, use a multimeter to measure the continuity of a line; first, make sure that the other line is open, then connect one end of the measured line to the other, and then use the on-off of the table on the other end of the two lines. Whether the wire head of the two wires is open, if it is open, the general resistance of the watch is 0, and both are accompanied by a prompt tone, and vice versa. Use a multimeter to measure the voltage more often; for example, to see if there is power, whether there is output, or so on.