How to check for a broken internet cable. Testing cables and wires - methods, diagrams, testers How to check an Internet cable for damage

Did you know that when installing or repairing a computer network and communications, sometimes you need to check the twisted pair to determine its integrity, the absence of short circuits and correct crimping? You can check it with special equipment (using LAN testers and multimeters). But due to the lack of the necessary device, the cable is checked using simple methods at home. In the article we will talk about how to find out the reason for the cable termination and how to correctly check the twisted pair in various ways.

No Internet access: what to do?

What should you do if a window suddenly pops up on your computer monitor informing you that there is no connection and the diode on the network board is not lit? There are a number of options to solve the problem.

First, try inserting and removing the RJ-45 male connector. If there is still no access, then the hope for a poor connection has collapsed, because the reason lies elsewhere. For example, this may be due to a separate network card installed on the PC. Ask why the connection dropped if you didn't do it? User participation in the shutdown may not be necessary. The following factors will handle this for you:

unstable voltage in your network;
use of unlicensed programs (downloading and launching them);
presence of viruses on the PC.

How can I check this? For example, Windows XP users can perform the following sequence of actions: Start – Settings – Control Panel – Network Connections. During the last step, you can find out whether the connection is connected or not. Also, users of this OS can check the correct operation and configuration of network card drivers, because they are often another cause of connection problems. In this case, the sequence of actions is: Start - Settings - Control Panel - System - Hardware - Device Manager - Network Cards. Once you've taken the last step, make sure there are no warning signs.

The problem with this card may be related to lightning or thunderstorms. To do a sanity check, connect it to a working line or install it in a completely different PC. Before doing this, do not forget to install drivers for it. Try moving the card to the nearest slot on the board, as sometimes this helps.

If all these methods do not solve the problem, contact your provider's support team. Perhaps the reason is a glitch on their lines. But if everything is fine with this, then the problem is a malfunction of the twisted pair cable. Among such malfunctions are:

one or a number of wires break completely, which happens very often;
Less often, a short circuit occurs, which can be in one twisted pair between its wires or in the conductors of the pairs themselves, which are closest.

Therefore, the twisted pair needs to be repaired. You can carry out repair work and inspection yourself without the help of specialists. We will talk about how to check a twisted pair further.

Using test programs

People often look for some kind of miracle program that will help them determine the condition of their twisted pair cable. But few people know that such options exist on their computer. This program makes its existence known when you discover that there is no cable connection. The corresponding inscription is a signal about an open circuit or short circuit that occurs in a twisted pair cable. True, it is impossible to find out exactly where the problem occurred using the program. The malfunction can only be determined independently using special testers, which include MicroScanner Pro, the capabilities of which we will return to later.

If there is an unstable or very slow connection, then you should monitor the traffic. We recommend using a free, innovative program called Network Traffic Monitor. With its help you can do the following:

measure data and the speed of its transmission over the network;
analyze speed changes over a certain time;
save all relevant information on the hard drive;
possibility of extensive settings;
support of a large number of languages;
use of various services.

Installing the program will not take much time. All you need to do is launch the EXE file and click on the button that confirms your actions. After downloading and installation, monitoring will be performed and all necessary data will be saved. This program is considered the best in its analyzing and diagnostic kind. This is evidenced by reviews from experienced users.

About connecting a PC to an active network using twisted pair cable

In order to carry out a high-quality, effective test of a twisted pair electrical wire, you need to simply imagine the electrical circuit for connecting a twisted pair cable to a PC together with another device (hub or additional computer). We suggest that you familiarize yourself with the diagram in detail for a general understanding.

Particularly interesting when checking a twisted pair cable is the part with the depicted circuit diagram of the card or hub. The RJ-45 connector is connected to it, which we already mentioned earlier. It can be purchased in Russia at the Allotelecom store. Take a closer look and you will see that the connection of each twisted pair to the transformer itself is carried out in a symmetrical way. This means that there is a middle of the transformer winding, and there is a tap in it. It, in turn, is connected to the common conductor using a resistor and also a capacitor.

This connection guarantees the elimination of interference in the twisted pair that comes in antiphase. Instead, we receive a useful signal, the magnitude of which does not change. Another advantage of a transformer diagram is the protection of your equipment from tangled cable wires and short circuits.

About the swing strength and waveform of twisted pair

Many people ask this question, so we will try to give a comprehensive answer. After analyzing the oscillogram of the information signal, the following conclusions can be drawn:

The presence of signals of Rx and Tx types with the same shape and a swing of two volts.
One pair serves as signal transmission, and the other as reception, which is due to the presence of exactly two twisted pairs.
If any RJ-45 cable connector is removed from the device, the signal stops transmission automatically.
The signal has a circular shape.
Distance restrictions between different signal points (no more than 100 meters).

This suggests that a signal swing of two volts does not pose a danger to humans. In the same way, a short circuit is safe for the operation of network equipment. Therefore, it is quite possible to check twisted pairs without disconnecting the cable from the network. At the same time, you do not need to worry about equipment loss.

Tester is an excellent way to check

First, take a look at the electrical wire along its entire length, namely, look at how well the crimping is done in RJ-45 plugs. In case of poor-quality crimping, contact problems will arise due to the wires not being inserted all the way. Or they may be overlapped in a fixed place with each other, as a result of which the twisted pairs do not close. Couldn't notice the problem at first glance? Then use testers who perform quality testing.

Today there is an innovative cable tester that has an LCD display. We already mentioned it at the beginning of the article. What is MicroScanner Pro? The tester has many different functions and is designed to test twisted pairs. Standard tests performed include:

determining how correctly the wiring is done;
determining the location where the damage is present;
analysis of the nature of the fault (complete breakage of pairs, insufficient length of pairs, reversed conductors in one and two pairs);
determination of segment length;
calculation of 100% distance to the place where the fault is present;
tone-generating mode that traces the electrical wire.

It is, of course, possible to buy such a modern device, but it is not always necessary if you have the necessary funds at hand. This applies to a pointer tester or digital multimeter. With their help, you will measure the resistance of electrical circuits, voltage, and current (DC and AC). You will be surprised, but testing twisted pair cables with a multimeter is the optimal solution, the success of which is guaranteed.

A multimeter is the best way

First you need to turn on the resistance mode. Try to bring the cable ends together to a single point. If you succeed, then the check will be carried out in this order: checking the integrity of all cores separately; testing each cable according to its color; checking for short circuits with the following wires. If it is possible to establish a connection between the probes, resistance will be detected.

However, it often happens that it is impossible to bring both ends of a pair into one single point. Then you need to either cut off the connector or strip the wires at one end, connecting them in pairs to each other. After this, you should use a multimeter to probe each of the pairs at the other end. If time permits, take an old computer socket that has a working connector and short-circuit its internal contacts. Thanks to this, cutting of connectors and stripping of wires can be avoided.

Checking with a switch tester

This method is considered the simplest. With its help, dialing is carried out. Both green and orange pairs are affected. Your actions should occur in this order:

To begin, remove the RJ-45 connector from the PC network card.
Turn on the mode that will determine the resistance.
Touch the orange and white-orange wires using the device's probes.
Wait for the resistance reading to reach 1-2 ohms.
Touch the green and white-green wires.
Monitor for changes in resistance readings.
Measure the indicator between the green and orange wires using probes.
Expect readings from 100 ohms to infinity.

If the measurement was successful and showed results that are completely similar to the example, then the test indicated the working condition of the twisted pairs.

Having completed the check, you need to make a decision on how to proceed. If a pair of green or orange colors breaks, then one pair should be replaced with one that is not in use (brown or blue), but only if it is in working order. To do this, feel free to cut one fork, ring the pairs again, and then cut the second one, performing a second pair check. This is due to the fact that short circuits also occur in the plugs, namely in those places where the clamps are made with clamps. Therefore, if after cutting you find a defect, then inspect the entire length of the electrical wire more carefully. Still can't find the damaged area? Then consider replacing the twisted pair cable with new electrical wire.

About checking in the absence of a tester

What if the tester or multimeter is only available in the store, but checking the cable is necessary? We suggest trying a certain technique. To do this, cut pieces of 10-15 cm in size from each cable end (this includes connectors). Next, free the ends from the sheath by about 5 cm, after which remove the insulation from each conductor to a length of 2 cm.

After preparing the twisted pair, take a small container made of glass, plastic or polyethylene and fill it with water. Before this, you should add salt to the liquid, boiled until completely dissolved in water (there should be a quarter of the salt per volume of water). But keep in mind that if the volume of salt is larger, then this is even better, because with its help electrical water resistance is achieved. Next, place the end of the twisted pair wires into the prepared liquid. Please note that contact between the conductors is excluded, and therefore there must be at least a small distance between them.

What about the ends of the twisted pair, which are on the opposite side, then you need to connect in the correct order to any active power source that has a value greater than 3 V. But if there is too much salt in the water, then a value of 1.5 V is enough. It is possible to obtain voltage from any type of AA battery. You can also use a cellular battery (3.7 V). Use the following equipment as a power source:

a resistor with a nominal value of 50-100 Ohms. With it you will receive protection against twisted pair short circuits;
telephone network. It contains direct current and voltage of 40 V, which is safe for both communication lines and human life. This option is ideal for supplying voltage at the entrance, because there is a telephone box nearby;
mobile phone charger;
a computer USB port that has 5 V at the outer terminals and a load current of 20 A. But note that you can only connect it to the computer with a resistor that limits the current, otherwise the PC will fail.

After voltage has been applied, you will see what will happen to the other ends of the twisted pair in the water. The conductor connected to the negative should emit small white hydrogen bubbles. And the conductor that is connected to the positive will release yellow-green chlorine bubbles. If this happens, then everything is fine with the twisted pair and there is no question of a short circuit. If there is a short circuit, then hydrogen or chlorine bubbles will also come from the other conductor.

This way, you will find the damaged twisted pair and end the inspection process by replacing the damaged pair with a blue or brown sample. Don't know how to do this? If, while checking, you find a break in the orange pair, then connect its place coming from the connectors to the blue cable pair.

Despite this simple method, we still recommend crimping the cable with a new connector instead of splicing it. If you don’t have it, then you can always buy connectors in Moscow at affordable prices in the Allotelecom online store.

If everything is fine with the green and orange pair and you don’t want to crimp, then check the cut pieces of the twisted pair with the connector. To do this, twist together colored conductors that are protected from insulation and separately white wires. After this, insert the connector into the salt solution, completely immersing the contacts in water. Twist the wires and connect them to the battery. Make sure that white bubbles appear one at a time on 4 of the 8 contacts. Next, change the polarity of the battery connection so that bubbles form where they did not appear before and also one after another. If something goes wrong, then this is the first sign of a non-working twisted pair cable. There are no white bubbles on one of the contacts, which means the wire is broken, and if they are absent on all of them, it means a short circuit has occurred.

Potatoes and twisted pairs

First, prepare the twisted pair cable in the same way as you prepared for the salt solution. Next, follow this sequential check:

Take half of the raw potatoes that you need instead of a container.
Insert each twisted pair, one at a time, into the potatoes 1-1.5 cm.
Maintain a minimum distance between wires.
Watch what is happening around the connected wire: if it turns green near the positive terminal, and whitish foam forms near the negative terminal, then everything is fine with the wires. Well, if there were no changes in the cut, then the twisted pair is broken or shorted.

For this experiment, you can use half an apple. Experience has shown that with its help you can also find out about the serviceability of a twisted pair cable, although this does not happen as clearly as with potatoes.

Now you know about all the possible ways to test twisted pair cables, which are carried out by programs, testers, multimeters and traditional methods. This way you can check different electrical wires. We hope that this article was useful to you and you can now easily find out the reason for the failure of the twisted pair cable by carefully checking it.

allo-tele.com

Testing twisted pair cables at home.

When installing and repairing computer networks and communications, there is often a need to check the integrity of the twisted pair, the absence of short circuits, the correct crimping, and so on.

Of course, if you have the appropriate equipment (for example, a LAN tester or at least a multimeter), this task comes down to simply connecting a cable to the appropriate device and checking it using standard methods.

But the required device is not always at hand. Sometimes you need to check the twisted pair at home, so to speak “on the knee”.

Method 1. Checking the twisted pair with a multimeter.

I think that many people at home or in the garage have a multimeter, dial tester or similar device for measuring resistance, voltage and current in a circuit.

With this device you can very easily and quickly check a twisted pair cable for breaks, short circuits and overall performance.

The twisted pair is checked with a device operating in resistance measurement mode.

If it is possible to bring the ends of the cable to one point, then the test will be performed as follows - first, we will check the integrity of each core individually, to do this, we will test each cable one by one by color. Then we’ll check for a short circuit with other wires - to do this, touch one wire on one connector, and touch each one in turn on the opposite connector. Resistance should be shown only in cases where there is contact between the probes (in the first case, it indicates that the wire is in order, in the second, that there is a short circuit with the corresponding wire).

However, it is not always possible to bring both ends of the cable together at one point, so you can use the following trick: either cut off the connector, strip the wires at one end and connect them in pairs, each pair with each other. After this, test each pair at the other end with a multimeter. If you have the time and desire, you can take an old computer socket with a working connector and short-circuit the contacts inside it; this will make it possible not to cut the connector or strip the wires. Additionally, you can not only short-circuit the contacts inside the socket, but also connect them using resistors with different resistance values - then you can see if there is a short circuit between the pairs. (The resistance on the multimeter will correspond to the resistor value + a slight increase due to the length of the wire).

Method 2. Checking twisted pair cables without a multimeter.

If you don’t have a multimeter, but you still need to check the cable, then you can use the “old-fashioned” method: At one end, the wires are stripped to a length of about 5 centimeters and lowered into a glass of warm, highly salted water.

After this, at the other end of the cable, a voltage of more than 3 V is applied to one of the pairs. To do this, you can use a crown battery, a battery from a cell phone, or a battery from the motherboard. If you don’t have any of the listed power sources at hand, then you can use a standard 1.5V AA battery, but then the water needs to be heavily salted.

The container with water must be made of dielectric (plastic, glass).

After power is applied, the following will happen inside the glass: white hydrogen bubbles will be actively released at the cathode (negative pole), while yellow chlorine bubbles will also be actively released at the anode (positive pole). This means that the wires are in good condition, they conduct current and there is no short circuit between them.

Another original way to check is to insert one pair into the potatoes to a depth of 1-1.5 cm. And apply food in the same way as described above. After this, white bubbles should appear on the cathode, and the area around the anode connection will turn green.

In fact, there are a huge number of these “folk” methods for checking different cables. It would be interesting to know what methods you use, which ones you have heard of, etc.

avs-electronics.livejournal.com

How to check for a broken internet cable

If a PC owner encounters problems with the Internet and, when trying to connect to the network, sees the error “network cable not connected,” then most likely there are problems that will be quite difficult to fix on your own. A more reliable sign of cable damage is the absence of an LED signal at the input point of the Internet plug. Unfortunately, not all motherboards have a light indicating that a working wire is connected. This is also true for external network cards inserted into the PCE slot that do not have LED indicators.

You can try to solve this problem on your own. To do this, you need to determine what exactly caused the lack of Internet. Here are some of the most common problems that you can fix yourself:

Unstable mains voltage. This problem leads to many malfunctions in the computer, one of which is problems with the Internet. The solution to the problem is to install an uninterruptible power supply that protects against voltage surges.
Use of unlicensed software. One of the most common sources of problems when operating a PC is the use of unverified programs that can lead to errors or contain malware. Therefore, on computers used for work and containing important data, only licensed software should be used.
Network equipment is turned off. Sometimes internet problems can be caused by something as simple as a disabled network adapter. To check the activity of this device, you need to go to the “Control Panel” in Windows, find the “Network Connections” item, go into it and select the “Network Adapters” tab. In the window that opens, make sure the adapter is active.
There are no drivers for network equipment. This problem is especially relevant when reinstalling the operating system. To make sure you have drivers that match your network equipment, you need to go to the “Control Panel” tab, select “System”, open the “Device Manager” menu, find “Network Adapter” and look at its properties. If there are no warning error messages, then the problem is most likely not with the drivers.

All of the above errors can usually be resolved through the efforts of the computer owner.

Help from specialists

If the above-described causes of the malfunction do not apply or you cannot cope with the problem yourself, then you should use the help of professionals. The first thing you need to do if you have problems with the Internet or the power cord is to call the operator of the provider that provides network access services. Thanks to this, you can quickly find out if there is cable damage or any other breakdowns.

If, after calling the operator, the computer owner found out that there was no problem on the operator’s part, and also checked his PC for serviceability, then we can say that the cable is damaged. You can fix the problem by using the services of specialists from a company that provides Internet access.

In some cases, you can try to fix wire damage yourself. To do this, you need to know the possible types of breakdowns and how to eliminate them. The most common malfunctions that appear due to mechanical damage to the cable are the following:

The most common reason is a complete cable break. It usually occurs due to negative mechanical effects, such as overstraining or operation at temperatures exceeding the norm for a cable of this type.
Short circuit between twisted pair wires. This is also a fairly common cause of problems with the Internet. Also appears due to pressure and impacts.

If you find a cable break, you can try to fix the problem yourself. It is also quite easy to check the functionality of the network card, which is also often the cause of network problems. To do this, just install it in another computer and connect the Internet cable. But this opportunity is relevant if you have access to the network through a working wire.

To accurately determine the malfunction of an Internet cable, you must have knowledge of the correct connection of the wire through a switch, hub or other devices, as well as have general knowledge of the principle of transmitting information through twisted pair cables.

It is also advisable to familiarize yourself with the cable connection diagram. Basically, for wires transmitting any digital data, a transformer connection circuit is used to avoid interference. Thanks to the knowledge of the above-described causes of cable failure, anyone can eliminate the fault or broken conductor.

If you need to find a malfunction of equipment or electrical wiring, one of the operations that is performed first is to test the cables and wires with a multimeter (tester) to check the serviceability of the circuit (no breaks in it), the presence of a short circuit and determine its resistance (if necessary ). In this way, it is possible to easily and quickly check the serviceability of a lamp, iron, switch, fuse, transformer. This article will discuss how to test wires correctly with a multimeter.

What you need to know about the device to connect wires

If you plan to test the wiring in your apartment, you need to know several fundamentally important facts about multimeters. First of all, it is worth noting that you can check the wire with the simplest device. An inexpensive Chinese model with minimal capabilities is quite suitable.

But at the same time, it is most convenient to use a device that has the dialing function itself. In order to set the device handle to the appropriate position, you need to turn it in the direction of the diode icon (as an option, an image of a sound wave can additionally be applied). This means that when checking the integrity of the wire, a sound signal will sound when the contacts are closed.

But the presence of sound is completely optional for testing wires with a multimeter. The fact that the circuit is broken will be indicated by a unit on the display, indicating that the resistance level between the probes is higher than the measurement limit. If there is no damage in the area under study, the resistance value will be displayed on the screen, which ideally should tend to zero (subject to operation in short-distance household networks).

Sequence of actions when calling

Before you test the circuit with a multimeter, you need to turn the handle of the device to the desired position.
Install the ends (measuring leads) into the appropriate sockets. The black wire goes into the socket marked COM (sometimes it can be marked with “*” or a ground sign), and the red wire goes into the socket where the Ω sign is indicated (sometimes it can be marked with an R sign). It is worth noting that the Ω sign can be applied either separately or in combination with the designations of other units of measurement (V, mA). This is the correct position of the test leads, which will allow you to maintain polarity when making further measurements. Although if only the integrity of the wires is checked, their relative position will not affect the result obtained.
Turn on the device. A separate button may be provided for this, or activation may occur automatically when the knob is turned to the desired position when selecting measurement limits or operating modes.
Connect the measuring ends to each other. If a signal sounds, it means that the device is operational and ready for use.
Take the cable or wire being tested (its ends must first be stripped of insulation, stripped to a metallic shine, and dirt and oxides removed from the surface). Touch the test leads to the exposed areas of the conductor.
In case of continuity, a signal will sound, and the device readings will either be 0 or indicate the resistance value. If the display shows 1 and there is no beep, the tested conductor is broken.

Rules for safe calling using a multimeter

testing the network cable with a multimeter

Working with electricity does not allow for unprofessionalism, so a certain list of rules has been developed that make it possible to make it as accurate, fast and safe as possible.

When making calls, it is most convenient to use special tips at the ends of the measuring wires, which are more commonly known as “crocodiles”. They will make the contact stable and free your hands when taking measurements.
When testing, the circuit being tested must always be de-energized (even low-current batteries must be removed). If there are capacitors in the circuit, they must be discharged by short-circuiting. Otherwise, the device will simply burn out during work.
Before checking the integrity of a long length of conductor when taking measurements, it is important not to touch its bare ends with your hands. This is due to the fact that the resulting readings may be incorrect.

When testing a multi-core cable, it is necessary to separate and strip all existing cores from both ends. After this, you need to check the circuit for the presence of short circuits in it: to do this, a “crocodile” is attached to each core in turn, and all the remaining ones are touched with the other measuring end in all possible combinations.

Check to see if there is a short circuit between the cable cores. If the indicator shows “1” and there is no sound signal, then everything is in order, otherwise there is a short circuit.

In this case, a sound signal will indicate the presence of a short circuit between the tested wires. This may not be of practical importance for small cross-section multi-core cables operating in low-current networks, but when working with high voltages it is fundamentally important.

We call the cable cores. There is a sound signal - everything is fine, otherwise the core is damaged.

To determine the integrity of the cores, the same operation is performed, only at one end of the cable all stripped cores are twisted together. When searching for a break, it is important to consider that the absence of a sound signal at either end will indicate a violation of the integrity of the conductor.

We check the wiring in the apartment with a multimeter

Let's take as an example a modern apartment in which the wiring is done in accordance with current requirements and standards. This means that when laying the lighting lines and power outlets, they were separated, and separate wires were laid for them in each of the rooms. Each of these circuits is powered from the apartment panel through a separate circuit breaker.

If the light has gone out in one of the rooms, you should first check that the lamp is working properly. Before starting work, it is necessary to de-energize the room/apartment depending on the power supply. When using an opaque incandescent lamp in a lamp, the integrity of the filament is difficult to visually determine, so you will need a multimeter and its continuity function. Let's figure out step by step how to do this correctly.

First you need to check the shield for triggered circuit breakers. In the first case, they will be in the on position (then the fault may be hidden in the room switch, lamp or socket). The likelihood of damage to the wiring in such a situation is low. If the device works, you will need to check everything except the room switch, including the switchboard itself.

If the machines don't work

We ring the switch. When the switch is on, there should be a sound signal, when off, there should be silence and “1” on the indicator.

Make sure there is voltage at the input and output of the machine. If it is, you can proceed to further verification.
Prepare the device for operation and check its serviceability by short-circuiting the measuring leads.
Unscrew the lamp from the socket.
Touch one of the measuring probes to the base (the metal part of the lamp with threads), and the second to the central contact of the lamp (the insulated center of the end part of the base).
A sound signal and instrument readings that are different from 0 or 1 mean that the lamp is working. If it is faulty, you need to replace it, which will solve the problem.
We check the cartridge for serviceability. To do this, you need to disassemble the lamp, make sure that the connected wires and contacts are intact. If everything is in order, then the cause of the failure is not in the cartridge. If malfunctions are detected, they must be eliminated. The lamp cannot be screwed in yet.
We check the serviceability of the room switch. To do this, remove the plastic cover, unscrew the screws and take it out of the mounting box. We inspect the equipment for the appearance of carbon deposits and check the tightness of the fasteners. If everything is in order, you need to install the measuring ends of the tester on the contacts of the switch. The appearance of a sound signal when dialing in the on position will indicate that the equipment is working properly. The wires do not need to be disconnected.

During such a check, as a rule, a malfunction is identified, which becomes the cause of all the troubles. Eliminating it allows you to quickly solve the problem.

If the machine worked

To ensure electrical safety during work, in this case the voltage is turned off using a general apartment circuit breaker. Next, the serviceability of the socket and the wires connected to the lamp is determined according to the algorithm described above. If there are no faults, you need to check the wiring itself using a multimeter and the continuity function. Such malfunctions happen quite rarely, but they still happen, for example, when installing suspended ceilings or decorative interior elements.

The wiring in this case is performed as follows.

Using a screwdriver, disconnect the connected conductor (if installed correctly, it is located at the bottom) and move it to the side. The “zero” of this group is, as a rule, located at the zero clamp under the machines.
Unscrew the incandescent lamp from the socket. Using a ready-to-use tester, we check the line by connecting one of the measuring probes to “zero” and the other to the disconnected conductor. If the device beeps, it means the wiring is shorted.
In this case, in the room under the ceiling above the switch, we find and open the junction box. We disconnect the wires.
We check all groups of wires for short circuits.
To determine the section of the circuit in which there is a short circuit, we again check the circuits on the apartment panel with a multimeter. If the signal sounds, it means that it is the wire laid from the switchboard to the box in the room that needs to be repaired. Otherwise, the search will need to be continued until a result is obtained.

Video

From all of the above, we can conclude that having a multimeter with a dialing function in the house is an objective necessity for any home craftsman. With such a device, in most cases it will be possible to quickly eliminate minor faults without turning to specialists for help.

A local network with an Internet connection is now available in almost every home. Network problems happen, and unfortunately, it’s not possible to identify the problem right away. It is necessary to check each network component at the software and hardware level.

Algorithm of actions

Let's consider the situation. There is a computer in the room. It is connected via a patch cord to the router, which, in turn, is connected via an Internet cable to the provider’s equipment to access the global network. At one point, the network checker on the computer shows that the connection is unavailable or not connected.

What to do:

Check the local interface of the computer you are working on - rule out software errors in Windows or hardware failure of the network card.
Check the operation of the section from the computer to the router - rule out a network break in the PC - router section, a malfunction of the software or hardware of the router responsible for the local network.
Send requests to one or more remote servers of large companies to check the functionality of the cable or equipment that goes and is located outside your home.

To walk through the troubleshooting algorithm, work with the network commands.

Troubleshooting

A superficial check can be done using the command to ping all hosts on the home network and several remote Internet servers. For these purposes, open a command prompt as an administrator. Next, enter the commands, focusing on the algorithm of actions:

Testing the operation of the network card of the computer itself is done by exchanging test packets with itself. If there are no losses, then everything is in order. Team ping 127.1.1.0.

You can add the -t option to make the packets go on forever until you manually stop them with the Ctrl+C key combination.

Next, ping the area to the router. It is important to ensure that the Internet cable between the computer and the router does not break. If there are packet losses, reboot the router and try pinging again. If the local IP address of the router has not changed, then it is 192.168.0.1 or 192.168.1.1.

When 100% of the number of packets reaches the router, the next step is to ping one of the remote servers. This way you can check if you can access the Internet. It is recommended to ping the IP address of the server of a large corporation, as this eliminates the fact that it is unavailable on the network. It is not necessary to know the IP address; you can ping by domain name.

Analyze the information received.

Fault Analysis

We will start from the losses received when sending packets. It is important to understand that the ping command is a protocol of the fourth level according to the nesting of the OSI model, that is, software, network and hardware errors are excluded, but data levels 5-7 according to the OSI model are not checked.

It turns out that a cable break, if present, can be identified in this way and is the easiest to do. But the programs do not allow you to identify the specific location of the cable failure, but only indicate the area.

How to check an Internet cable or local cable and understand that there is a break? Eliminate other options related to a faulty network card or router. If there were packet losses when scanning the computer itself:

Restart your network connection.
Disconnect from all network add-ons (VPN, proxy).
Do a Network Reset.

Update or reinstall the network card driver.

If packets are lost in the PC-router section:

Reboot your router.
Check that the Ethernet cable connectors are securely seated in the port of the router and the network card (motherboard).
Switch the Ethernet cable to the next port on the router.
Restore the router to factory settings.

Check the connected port indication on the router. If it doesn’t light up, there are two possibilities: the capacitors on the router board have malfunctioned (or another hardware failure of the router) or the cable is faulty.

If packets are lost when accessing the Internet:

Reboot your router.
Free up a dynamic IP address in your router settings.

Turn off VPN and proxies.
Ping other remote servers to ensure that the server is not accessible.
Load Internet pages through another browser.
Restore your router to factory settings.
Call your provider to find out the cause of the problem.

If packets are still not being passed through, there are three possible reasons: a faulty Internet cable, a problem with DNS processing, or problems with the provider’s equipment.

Checking twisted pair breakage and insulation integrity

The following video describes 5 ways to test twisted pair cables:

If all indications are that there is a problem with the cable, it must be identified and corrected. If a short cable is faulty, you can simply replace it. For wires several tens of meters long, you can use special devices to help identify the problem.

Tester

MicroScanner2 is a professional solution for identifying the location of cable faults. By connecting one connector to the port, graphical information about the length of the patch cord to the fault location will be displayed on the tester screen.

Other methods require removing the connector and taking measurements directly on the twisted pair contacts. It would also be a good idea to check the quality of the cable crimp with the connector. If the crimp is weak or the insulation is broken, problems with signal transmission are guaranteed.

Multimeter

In resistance mode, you need to ring the orange and green twisted pair to check the integrity of the cable:

Remove the second connector from the PC's network card or other network equipment.
Remove the connector from the end to be measured and expose the wires.
Apply the tester probes first to the orange and white-orange conductor of the twisted pair. Normal resistance is 1-2 ohms.
Next, apply to green and white-green. The resistance should also be 1-2 ohms. The polarity is not important.
Then attach the multimeter probes to the orange and green conductors. The multimeter should read more than 100 ohms. Multimeters usually indicate infinity.

Regular potatoes

If you don’t have any devices at hand, and you need to find out if the cable is damaged right now, do the following:

Cut the potatoes in half.
Immerse each pair as close together as possible into the potatoes, 1.5 cm deep.
If the wire is connected to the positive, the area around the immersed conductor will begin to turn green.
If the conductor is connected to minus, then white foam will appear near the conductor. If you pull out the negative wire, it will begin to darken.
With zero changes in the state of the potato, the twisted pair is most likely shorted or broken.

Conclusion

If you have problems accessing the global network, you need to identify the cause of the problem. It happens that Internet access is blocked because there is a cable break in a section of the local network or with a patch cord connected to the WAN. It is best to check the integrity of a twisted pair cable using a tester, since it does not require removing the crimped connectors. If there is no such device, use a multimeter or more accessible methods.

You can try to solve this problem on your own. To do this, you need to determine what exactly caused the lack of Internet. Here are some of the most common problems that you can fix yourself:

Unstable mains voltage. This problem leads to many malfunctions in the computer, one of which is problems with the Internet. The solution to the problem is to install an uninterruptible power supply that protects against voltage surges.
Use of unlicensed software. One of the most common sources of problems when operating a PC is the use of unverified programs that can lead to errors or contain malware. Therefore, on computers used for work and containing important data, only licensed software should be used.
Network equipment is turned off. Sometimes internet problems can be caused by something as simple as a disabled network adapter. To check the activity of this device, you need to go to the “Control Panel” in Windows, find the “Network Connections” item, go into it and select the “Network Adapters” tab. In the window that opens, make sure the adapter is active.
There are no drivers for network equipment. This problem is especially relevant when reinstalling the operating system. To make sure you have drivers that match your network equipment, you need to go to the “Control Panel” tab, select “System”, open the “Device Manager” menu, find “Network Adapter” and look at its properties. If there are no warning error messages, then the problem is most likely not with the drivers.

All of the above errors can usually be resolved through the efforts of the computer owner.

Help from specialists

The most common reason is a complete cable break. It usually occurs due to negative mechanical effects, such as overstraining or operation at temperatures exceeding the norm for a cable of this type.
Short circuit between twisted pair wires. This is also a fairly common cause of problems with the Internet. Also appears due to pressure and impacts.