Working principle of network cable tester

Introduction to Network Tester
A network tester is usually also called a network tester or a network tester. It is a portable and visual intelligent detection device that can detect the operating conditions of the physical layer, data link layer, and network layer defined by the OSI model. It is mainly suitable for local area network failures. In the inspection, maintenance and construction of integrated wiring, the functions of the network tester cover the physical layer, data link layer and network layer.

Network tester classification
1. Network testers can be divided into wireless network testers and wired network testers according to the network transmission medium.

2. Network testers can be divided into cable testers, multi-function network testers and network performance testers according to their functions.

3. The network tester can be divided into network construction equipment and network maintenance equipment according to its purpose.

The working principle of the network cable tester_how to use the network cable tester

Network tester use range
LAN management

With the rapid development of the network, the stability and security of the network have become important in enterprises and institutions, and the responsibilities of network administrators have also increased, and heavy network failures will follow. Network testers are just such a kind of A good helper who can solve problems for network administrators.

  Integrated wiring

In the construction of network cabling, it is a tedious task to detect the connection quality and length of the network cable and the positioning of the network cable port. The network tester can help the construction staff make a quick and accurate judgment.

  data center

The smoothness of the network in the data center plays an important role, and the network tester can help network maintenance personnel quickly locate the fault.

width business

User broadband failure is a headache for broadband business companies. Whether the failure can be resolved quickly and the stable operation of the network directly affects the company's image and reputation. Network tester is an indispensable tool for technical support personnel.

  Network room

Computer room failures are very frequent. Equipping with a network tester can reduce the time for administrators to troubleshoot.

The working principle of the network cable tester_how to use the network cable tester

The working principle of network tester
According to Yuanjiao NS-468 computer network tester, the electrical schematic diagram is drawn as shown in the attached drawing. The component numbers in the figure are marked by the author for easy reading. The usage method of the network tester will not be explained here, please refer to the instruction manual attached to the tester. The following describes the working principle of the network tester.

The working principle of the network cable tester_how to use the network cable tester

K31 is the power switch. K32 is a fast and slow test switch, K32 is closed for slow test. Transistor T31, T32 and peripheral components form a clock pulse forming circuit to provide a clock signal for U21. Whether the clock pulse forming circuit works normally is reflected by the LED31 display. The integrated circuit U21 (model MC14017B) is a decimal counter. It inputs clock pulses from CLK pin, outputs high and low levels from Q0 to Q7 in turn, and scans the on-off status of the eight cables of the network cable. The on-off, interleaving, and short-circuit of the cables are determined by LED11～LED18 and LED21～LED28 show reflection. For example, at a certain moment Q0 outputs high level (Q1～Q7 output low level), the current goes from Q0→LED21→CN21 (RJ45)→the first cable of the network cable→CN11 (RJ45)→LED11→D12, D13→CN11 ( RJ45)→The third and fourth cables of the network cable→CN21 (RJ45)→D22, D23→Q2, Q3 form a loop. The LED21 of the main tester and the LED11 of the remote test terminal both glow, indicating that the first cable of the network cable is connected. . The principle analysis of other seven routes is similar.

network tester common failure maintenance
One, close the power switch K31, the light-emitting diode LED31 does not flicker and emit light. There are two main situations for this failure:

1. The battery power is insufficient. Measure the battery terminal voltage with a multimeter in the DC10V file. If the battery terminal voltage is too low, replace it with a new 9V stacked battery.

  2 . Most of the time, the transistors T31, T32 and peripheral components have false soldering, and the clock pulse forming circuit stops oscillating. You can test the level of pin 14 of U21 with the DC10V file of a multimeter. If the pointer of the multimeter does not oscillate periodically, it means that the clock pulse forming circuit has stopped oscillating. Find out the virtual solder joints and repair them.

Secondly, when testing a known intact network cable, LED31 flashes and emits light, but neither LED11 to LED18 nor LED21 to LED28 emits light, or only partially emits light. There are two main situations for this failure:

1. Most of the time, part of the components in LED11～LED18 and LED21～LED28 are soldered, and even the pins are separated from the PCB due to the pressure of the light-emitting diodes during installation. Find out the virtual solder joints and repair them.

2. U21 is damaged by static electricity due to improper use; or the live test network cable or telephone line damages U21. Use a multimeter DC10V file to test the levels of pins 3, 2, 4, 7, 10, 1, 5, and 7 of U21. Normally, each pin should have periodic high-level pulse output, otherwise U21 will be damaged. Replace it with an integrated circuit of the same model.

How to use the computer network cable tester
Nowadays, cables are used in all aspects of people's production and life. Therefore, mastering the operation method of network cable tester is the basic requirement of cable users, so how to use network cable tester? Let me introduce to you.

1. Plug the two ends of the network cable above the main and auxiliary measurement lines respectively, you can plug in either end;

2, then turn on the switch of the line measuring instrument;

3. Observe that the 1-8 indicator lights on the main and auxiliary line measuring instruments are not bright, and the order of the lights is correct.

4. For example, light 1 on the main line measuring instrument is on, and light 1 on the auxiliary line measuring instrument should also be on. If the 1 light on the main line measuring instrument is on, and the 2 light on the auxiliary line measuring instrument is on, it means that there is a problem with the network cable and it cannot be used normally;

Among the 5 and 8 lights, as long as the 1, 2, 3, and 6 lights are on, the network cable can be used, because the data is transmitted through these 4 wires, and the remaining 4 wires are not used to transmit data.

There are two standards for the order of the network cable:

1: T568-B standard, the order is orange-white, orange, green-white, blue, blue-white, green, brown-white, brown.

2: T568-A standard, the order is green and white, green, orange and white, blue, blue and white, orange, brown and white, and brown.

Generally used are standards.