Asus router DIY repair

In detail: do-it-yourself asus router repair from a real master for the site my.housecope.com.

Hello dear forum participants!
I ask for help in connection with the repair of the ASUS RT-G32 WiFi router.
The router was admitted with “does not turn on” symptoms.
Initial diagnostics revealed the presence of an open circuit voltage on the power supply (not shown in the photo) v = 16v, at a nominal value of 12v.
This circumstance was attributed to the low power of the standard power supply in the sense that it should noticeably sink under load.
Powering the device from a 12V stabilized power supply did not change the position - the device showed no signs of life.

A study of the device circuit showed the presence of an input filter for power supply in the form of 20mF 35v capacitors (marked with numbers 1 and 2 in the photo) and inductance (installed next to the capacitors, not numbered in the photo).
The capacitors have an input voltage.

Not having the qualifications to track the 1499 harness for the purpose of reconstructing the circuit and figuring out the pinout card for the 1499, it was decided to power the device from an external source. The supply of an external stabilized voltage of 3.3V allowed the device to start up and find itself on the network by its IP address, that is, the processor is working, the firmware has not crashed and at least one wired interface is working.

In connection with the above, I have questions:
1) Are there any other components that are powered directly from the 12V input voltage? (I do not see them and looking at the circuit I am inclined to believe that they do not exist and cannot be due to the wide range of possible supply voltages, which is indirectly confirmed by the high rated voltage of the input capacitors, but maybe I’m wrong)?
2) whether the 3.3 V power supply is sufficient or 5 V is necessary (my opinion is that there is not much difference between 3.3 V and 5 V, since this voltage, it seems to me, is not directly supplied anywhere, but is reduced by the converter, and 5v will lead only to more heating 1117)?
3) where to find the datasheet for 1499?

Video (click to play).

A router is used to connect to the Internet several devices, a computer, laptop and others, via wired or wireless technology and create a local network between these devices. At the same time, the router implements a barrier between the local network created by it and the Internet. Basically, routers work using NAT - Network Address Translation. Sometimes providers provide routers with the connection, the router can be inside a DSL modem or cable, or purchased separately. But, like any electronic device, routers can fail and many malfunctions can be eliminated at home on their own. Let's consider some common malfunctions of routers and methods of their elimination, repair of a d link router.

Most often, the following reasons lead to router malfunctions:

large voltage surges in the network,
overheating of the router,
router software crashes (firmware crashes),
high-frequency interference of electromagnetic radiation during a thunderstorm (in this case, the wan port most often burns out if the provider does not install lightning protection on its cable),
human factor.

If the router malfunctions, it can lose data packets, work on the Internet and the local network is disrupted, the firmware gets lost, the router can turn off, all indicators blink.

Solving a malfunction related to the impossibility of entering the settings of the router at its network address 192.168.0.1

If, after typing in the address bar of the router's network address, the router settings page does not open, then to eliminate this malfunction, you should perform the following operations:

First, check that you have set in the settings of the network card to automatically obtain for the IP address and DNS address (using a direct connection to the router).

If the settings of the network card are correct, then you must use the Run command (press the key combination Win + R), then enter - cmd and press enter. Now you need to enter ipconfig on the command line.

In the displayed settings, you need to see what value is opposite the inscription - Default gateway. This address is used to enter the settings of the router. If the value of this address does not match the standard value, then the router may have been configured for a specific network with its own requirements. In this case, you need to reset this value to the factory settings. Sometimes this field may not contain the address value at all, and you also need to reset the router. To reset the router, you need to press and hold the Reset button on the router for a while. Usually five or ten seconds are enough. The button hole is narrow enough so you can use a ballpoint pen, needle or paper clip to press it.

If resetting the router does not help, disconnecting the ISP cable from your router may help. Pull out the provider's cable from the router connector and configure the router without a cable connected. After that, you can reconnect the cable to the router.

Also check the firmware version installed in the router. Check the latest firmware version on the manufacturer's website and update it if necessary. You can also check the drivers of your network card on your computer and reinstall them if necessary.

To troubleshoot a problem with not saving the settings of the router or if it is impossible to restore the settings from a separate file, you can try to carry out these operations by opening another browser. This method can help with other router malfunctions.

There can be many reasons for such a malfunction, and they are all approximately equally common. Let's consider the main possible causes.

If the network of your router is not displayed on the laptop in the list of available networks, then you need to check that the wireless network module is turned on. This can be done by looking at the adapter settings in the Network Sharing Center on your laptop. The wireless connection must be turned on. In the off state, it will be grayed out and you will need to turn on the wireless connection. If you cannot turn it on, then you need to check if there is a Wi-Fi switch on your laptop and turn it on.

If, despite the fact that the wireless connection remains on, but shows the status - No connection, then you should check if the correct drivers are installed for the Wi-Fi adapter and, if necessary, install them. The drivers must be downloaded from the website of the manufacturer of your equipment. This avoids possible driver incompatibility issues.

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In addition, you can try to go to the router menu and change the value for the settings there and change the b / g / n parameter to b / g. If this change helps, it means that the 802.11n standard is not supported. You can also see how the wireless network channel is specified in the same settings, and if it is set to Automatic, then select a channel from the list.

If you have frequent connection breaks during work, it is recommended to update the router's firmware. In many cases, this procedure will solve the problem.

Sometimes when working with some Internet providers to access local resources (torrent trackers, game servers), you need to configure static routes in the router settings. Such settings can be found on the forums of the provider that provides you with the Internet.

Surely, many have already come across the fact that the weakest point of many routers is their power supplies. They often break down due to large voltage drops in the power grid and the failure of individual elements as a result of long work.

Defective or low-quality elements, a circuit that is not designed for some margin, can also lead to breakdowns. Some typical faults of power supplies can be distinguished. In this article, we will consider repairing a power supply for a D-Link router. Power supplies such as JTA0302D-E and the like are used for Asus and D-Link routers, designed for an output voltage of 5V and a maximum current of 2-3 A. The appearance of such power supplies can be seen in the figure below.

If we consider the circuit and design of similar power supplies, then this is a diagram of conventional single-ended switching power supplies. In such circuits, a PWM controller is used for control, which controls the operation of a field-effect transistor, which is connected to its output. As a result, the voltage is reduced to the desired value and rectified, and it is supplied to the output. A schematic diagram of such a power supply can be seen in the figure below. In this diagram, depending on the model of the power supply, there may be some minor changes in the ratings of individual components. The power supply delivers a voltage of 5 volts. This voltage should not drop significantly under load (with the router turned on).

To repair the power supply, you may need to use a soldering iron, solder, multimeter, knife and electrical tape. To open the plastic case of the power supply, you need to cut the glued seam of the case. This operation can be done with a knife, but it is more convenient to use a small bur-machine for these purposes.

If you look at the power supply circuit in Fig. 2, you can see that a 2 ampere fuse, a choke, a thermistor and a rectifier bridge of four 1N4007 diodes are installed at the input. If there is a large voltage surge in the network, then all these elements can burn out. They can be easily checked with a multimeter by measuring their resistance. To smooth the rectified voltage at the output, after the diode bridge, a large capacitor is placed - C1 (22 or 33 μF). This capacitor should be 400V, no less. If he is out of order, then this can be determined by his appearance, he swells.

In addition, a positive voltage from the diode bridge is applied to a PWM microcircuit, in this case UC3843B. This microcircuit is used to control the opening and closing of the field-effect transistor P4NK60Z. Often the power circuit of this microcircuit contains a malfunction. In this circuit there is an electrolytic capacitor C6 and a zener diode ZD1, which is designed for a voltage of 20 volts. This capacitor must be of a certain capacity so that during operation the voltage supplying the microcircuit is always within the permissible operating limits. Therefore, the recommended capacitance of the capacitor is 100 μF. If the capacitor is dry, then the capacity will not be enough to start the microcircuit,

It is quite difficult to determine by external signs such an inoperative capacitor. The small size does not allow you to notice some bulge on its lid. You can measure the capacitance of a capacitor, but there is often a large drop in ESR with normal capacitance. To check the ESR, special measuring instruments are needed, this cannot be checked with an ordinary multimeter or tester.

In case of voltage drops, the zener diode ZD1 may fail. This can be seen from the darkened (charred) body of the zener diode.

In rare cases, the P4NK60Z field controller may fail. This transistor is supplied with a voltage of 13-15V. from the PWM output. The efficiency of the field-effect transistor can be checked with a multimeter (tester) switched to the diode test mode. On the drain-source channel, the voltage drop is 0.6-0.8 V.

If the voltage at the output of the power supply is 5 V, and when the load is connected, it drops to about 2 V., then most likely the electrolytic capacitors at the output of the power supply (C9 and C11) have dried up. To eliminate this malfunction, it is necessary to replace the dried electrolytic capacitors with working ones with the same characteristics.

In general, the main steps of the repair can be identified.If there is no voltage at the output of the power supply, then it is necessary to check for breakdown by measuring the resistance F1, TR, rectifier bridge. To provide some starting margin, it is advisable to use the capacitor C6 of 10 μF and designed for 50V, and not 47 μF and 25V. as usual in the diagram.

In cases where the output voltage drops, unstable operation of the power supply is observed, it is necessary first of all to replace the electrolytic capacitors C1, C9, C10, C11.

In addition, you can recommend several recommendations to improve the performance of the power supply. At the output of the power supply, a 220 Ohm 0.125w resistor is usually installed, filled with a special sealant. This resistor operates at its limit values and therefore gets very hot. Heating causes the condenser C9 to dry out. It is advisable, instead of a 220 ohm resistor, to put a 300 ohm resistor and a power dissipation of 0.5 watts. If a capacitor C9 for 10v is installed in the circuit, then it is better to put the same one instead, but designed for 16v.

After repair, the body must be assembled. But you do not need to glue it, but fasten the two halves, for example, with a coupler, so that in the future, if repair is necessary, it can be easily disassembled again.

They brought me an ASUS RT-N16 router with a diagnosis - "it does not turn on, but the power supply is working." The piece of iron is not bad, throwing it away is not good. They asked me to see if the repair was simple.

“A trifle, now I will replace the food containers and that's it! It's even boring! " - I thought, but it was not so ...

All the containers turned out to be normal, and I decided without the help of the Internet, for the sake of training, to figure out what was the matter.

By a cursory examination, I determined that there are 3 secondary power supplies on the board. The measurements revealed the following voltages: +1.3 V, +5 V and ... But with the third, it turned out to be a problem, nothing at the output. Checked the power line, no short circuit. The outgoing choke L51 was soldered off from the power line, weak 3.3 V appeared on it. That's the answer! The 3rd power supply is 3.3 V. I fed it from the laboratory power supply 3.3 V and lo and behold, the router started up, a Wi-Fi network appeared.

I began to check the power supply +3.3 V. The oscilloscope did not show any activity on the Q4 IRF7313 keys, the keys themselves are ringing normally. On the U28 microcircuit, too, only the input voltage of 12 V and silence.

The verdict is clear, U28 is for replacement, but it has no marking, it is invisible even under a microscope. And here the Internet has already helped. I found a photo of the board, where you can see the U28 marking, it's CAT7581CA.

Searches for this microcircuit on the Mitinsky radio market and in other places did not lead to anything, all paths led to Aliexpress. The microcircuit was ordered and at the same time all the containers.

It took 3 weeks, the package arrived. U28 CAT7581CA was installed in place, +3.3 V immediately appeared. The router made fun of sharing the internet. And I decided to go over the power sources and lay out the measurements, suddenly someone will come in handy.

The + 1.3 V source consists of a U32 RT8101A control chip and Q12 FDS6982AS keys.

The +5 V source is made on a single U20 CAT7199CA microcircuit.

The + 3.3 V source, as well as +1.3 V, is made on the U28 CAT7581CA control chip and Q4 IRF7313 keys.

The repair took a long time, of course. All elements: 3 types of capacities (16 V 470 uF, 25 V 470 uF, 16 V 1000 uF) and a microcircuit, were ordered in reserve in 5 times the size, cost less than 500 rubles.

Not expensive, but a good thing is back in the ranks. And I still have spare parts.

There is an indication, the router is loaded and will soon return to its owner.

First, the router is always connected to the network. Consequently, the power supply is constantly overheating, which can inevitably lead to network problems. If there is a strong heating, as well as a deviation of the current-voltage characteristics from the norm, replace the power supply. Of course, if the router is under warranty service, you can neither repair the power supply, nor replace it. Just take the defective item to the store.
Secondly, the quality of the mains voltage in Russia leaves much to be desired.As practice shows, any power surges disable the power supply. If you do not buy high-quality protection against undervoltage or overvoltage, the power supply of the router can easily fail. In this case, you can not count on free repairs under warranty.
Thirdly, do not forget about electromagnetic interference, as well as atmospheric electricity. It is very common when the router fails without smoke, burning - static electricity "kills" the devices gently. If the manufacturer has saved on protection against static electricity, which may occasionally appear on the telephone line, then there is a possibility of failure of the wireless equipment due to the direct or indirect effects of high voltage induced by lightning.
Fourthly, a complete failure of the router is possible due to problems with the firmware. If, during the process of updating the software built into the router via the web interface, at least a slight drop in the network voltage occurs (the light will blink), the power connector will come off, the network cable - the device will definitely become unusable. And the firmware restoration will be possible only in the service center.
And fifth, always remember about the human factor. It is no secret that the vast majority of problems with wireless equipment are provoked by the user himself. Some unique people manage to disable some LAN ports by connecting them inappropriately. There are also devices that have been broken by flashing via Wi-Fi. Naturally, this should never be done. This is written in plain text in all manuals. Only flash the router through the cable.

Many users face the problem when the router refuses to open the main setup menu. Users try in vain to type 192.168.0.1 or 192.168.1.1 in the Internet browser, but there is no result. The configuration interface is not available. In the event of a problem of this kind, it is necessary to perform the simplest manipulations, namely:

First, check the TCP / IPv 4 settings of the network card that is currently being used to connect to the router. It is necessary to set the switches so that both the IP address of the network card and the DNS server address are obtained automatically.
Secondly, if there are no positive changes, then you can restore the factory settings of the router. To do this, you need a ballpoint pen, with the tip of the rod of which you need to poke the hidden RESET button on the router. With the router powered on, hold this button down for 10-15 seconds. After carrying out these simple but effective manipulations, we will get a router with a standard network address 192.168.1.1, a pair of username and password of the standard form (admin, admin), as well as completely erased settings. Unfortunately, the erased network settings will have to be reconfigured, but this is a small price to pay for the ability to bring the router back to life.

Local area network without internet access is the most common problem on TP-Link wireless routers. As practice shows, the problem lies in the imperfection of the router firmware that comes from the factory. The solution to the problem lies in installing a new firmware version, where the above software malfunction is completely eliminated. Simply go to the website of the manufacturer of this technique, find your model of wireless equipment, go to the download section for manuals and software. Then you need to clearly define the version of your router. Please note that routers of the same design may differ significantly in their hardware. Therefore, having flashed the router with the wrong firmware, you, firstly, will lose the warranty for the router, and, secondly, you will receive a faulty device. Firmware recovery certainly takes place, but it is a rather specific and time-consuming procedure. Therefore, be extremely careful. The firmware procedure itself should be carried out only when you are 100% sure of the quality of the mains voltage, the reliability of the contacts, and the quality of the cables.It is best to flash by connecting the router not directly to an outlet, but through an uninterruptible power supply.

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Poor Wi-Fi signal, slow download speed, no router connection? Most likely, you need to configure or repair the device.C1-Technology engineers will be happy to help you solve any problem with ASUS network equipment and return your device to its previous functionality.

The spectrum of network equipment malfunctions is very large, ranging from mechanical damage to connectors or antennas, power supply failure, to the failure of the Wi-Fi module, for example, due to dust or other objects getting into the device. Remember, only specialists certified by Asus are guaranteed to eliminate the device malfunction and extend its life.

We carry out repairs of ACS network equipment, as well as eliminate malfunctions that have arisen during the use of the device.

I decided to prepare instructions for emergency recovery of firmware on ASUS routers. When, after an unsuccessful firmware, or some other action, the router does not turn on, all indicators blink, are constantly on, or only the power indicator blinks. Also, when the firmware fails, it is impossible to enter the settings of the ASUS router. Simply put, if after turning on the power of the router it does not work, does not ping and cannot open the control panel, then there is a chance to restore it.

I thought it would be wrong to write an instruction without checking everything on my own experience. Fortunately, I did not have an ASUS router with the flashed firmware. But unfortunately, I ended up with a practically new ASUS RT-N12 +, which I decided to turn into a brick and restore. Everything for the purity of the experiment Without hesitation, I decided to flash my RT-N12 + with firmware from another model in order to disable it. I downloaded the firmware from RT-N12VP B1, but it was not installed. The router is not "dead"! I tried several firmwares, but they were not installed. Then I decided to use the proven method: I launched a software update and turned off the power by about 15%. I turned on the router, but it did not boot anymore. The power indicator was constantly on, and the rest of the indicators blinked slowly at intervals of about 2 seconds. It was only later that I realized that it automatically went into recovery mode. Now I have a patient, I can restore him.

This instruction should be suitable for any more or less new ASUS router: RT-AC51U, RT-N10, RT-G32, etc. I have not tested it, but this method should also be suitable for restoring the original ASUS firmware after installing DD -WRT.

A small diagram of our actions:

Download the firmware and the Firmware Restoration utility from the official website. Strictly for our router model.
Install the Firmware Restoration utility.
Let's connect the ASUS router to the PC and put it into recovery mode.
Let's start the recovery process through the utility.
Let's wait until the firmware is restored and the router is rebooted.

Before moving on to this not-so-simple procedure, I advise you to reset your router's settings and try to go to its control panel. Perhaps you have a different reason, and you do not need all this.

First, we need to download the Firmware Restoration utility and the firmware for our router. All of this can be downloaded from the official ASUS website. On the page that is dedicated specifically to our router. Therefore, first we need to find out the model of the router. To do this, look at the sticker on the bottom of the device. I have ASUS RT-N12 +.

Follow the link and enter the model of your router in the search bar. For example, “RT-N12”. In the search results we find our model (it is important that the model exactly matches) and next to it we click on the “Drivers and utilities” link.

Next, select the version of Windows that is installed on your computer. Open the “Utilities” tab and download the “ASUS Firmware Restoration” utility by clicking on the “Global” link. We save it to the computer.

Then open the “Firmware” tab, and download the first firmware in the list for our router.

We should have two archives on our computer. The firmware must be extracted from the archive so that the file with the .trx extension is in the folder or on the desktop.

The folder with the Firmware Restoration utility can also be extracted from the archive.

Next you need install the Firmware Restoration utility... To do this, run the Setup.exe or Rescue.exe file in the folder. Installation is very easy, just follow the instructions. Upon completion, the wizard will offer to run the utility. You can agree, as the shortcut will not appear on the desktop. And in order to start it later, you will have to search in the Start menu.

The firmware has been downloaded, the utility is installed. You can go on.

On the computer, in the properties of the network adapter, you need to register a static IP address.

Right-click on the connection icon and select “Network or Sharing Center”. Then we select “Change adapter parameters”.

Right-click on the adapter “Local Area Connection”, or “Ethernet” (this is in Windows 10) and select “Properties”. In the TCP / IPv4 properties, write down the IP address 192.168.1.10 and the subnet mask 255.255.255.0.

Power on the adapter when finished.

Connect the router to a computer or laptop via a network cable.

Further attention!

Turn off the power to the router. You can pull out the adapter from the outlet, plug from the router, or turn off the button. I just pulled the plug from the router.
Press and hold the "RESET" button. It is usually signed “WPS / reset”.
Without releasing the "RESET" button, turn on the power of the router.
Continue to hold the button until the power indicator on the ASUS router starts blinking slowly.

In my case, the power indicator was on all the time, and all the other indicators were blinking slowly. But everything was fine, the router was in recovery mode.

If this happened to you, it means that the router has entered recovery mode. If not, try again.

Farther run the Firmware Restoration utility (if it is not running for you). Click on the "Browse" button and select the firmware that we downloaded. To start, click on the "Download" button.

If everything is successful, then the status should appear: “Loading the system restore file. “.

Further, the status of automatic system recovery.

We are waiting for the router to reboot. Everything, we can customize and use.

This error may appear at the very beginning, when the Firmware Restoration program cannot detect the router in recovery mode.

In this case, you need to check the router itself first. Whether it is in recovery mode. This can be understood by the behavior of the indicators. I wrote about this above. Try to close everything, restart the computer, check the connection of the router and restart it in this mode.Also disable your antivirus and firewall.

If this method did not help you, then on the Internet I found a video showing another interesting, and judging by the comments, a working version of restoring an ASUS router:

Apparently, ASUS routers are not software killable. And if the problem is not in the hardware itself, then there is always a chance to fix the router. Since it is very difficult to break its bay with the wrong firmware (and I checked it), it turns out that most often the firmware flies when the electricity goes out at the time of the software update. My Asus RT-N12 +, which suffered for the sake of this article, now works fine. And a couple of minutes ago, it didn't even boot.

Describe your cases in the comments, share tips and ask questions. I will answer everyone!

Is your TV, radio, mobile phone or kettle broken? And you want to create a new topic about this in this forum?

First of all, think about this: imagine that your father / son / brother has an appendicitis pain and you know from the symptoms that it is just appendicitis, but there is no experience of cutting it out, as well as the tool. And you turn on your computer, access the Internet on a medical site with the question: "Help to cut out appendicitis." Do you understand the absurdity of the whole situation? Even if they answer you, it is worth considering factors such as the patient's diabetes, allergies to anesthesia and other medical nuances. I think no one does this in real life and will risk trusting the life of their loved ones with advice from the Internet.

The same is in the repair of radio equipment, although of course these are all the material benefits of modern civilization and in case of unsuccessful repairs, you can always buy a new LCD TV, cell phone, iPAD or computer. And for the repair of such equipment, at least it is necessary to have the appropriate measuring (oscilloscope, multimeter, generator, etc.) and soldering equipment (hairdryer, SMD-hot tweezers, etc.), a schematic diagram, not to mention the necessary knowledge and repair experience.

Let's consider the situation if you are a beginner / advanced radio amateur who solders all sorts of electronic gizmos and has some of the necessary tools. You create an appropriate thread on the repair forum with a short description of “patient symptoms”, ie. for example “Samsung LE40R81B TV does not turn on”. So what? Yes, there can be a lot of reasons for not switching on - from malfunctions in the power system, problems with the processor or flashing firmware in the EEPROM memory.
More advanced users can find the blackened element on the board and attach a photo to the post. However, keep in mind that you replace this radio element with the same one - it is not a fact that your equipment will work. As a rule, something caused the combustion of this element and it could “pull” a couple of other elements along with it, not to mention the fact that it is quite difficult for a non-professional to find a burned-out m / s. Plus, in modern equipment, SMD radio elements are almost universally used, soldering which with an ESPN-40 soldering iron or a Chinese 60-Watt soldering iron you risk overheating the board, peeling tracks, etc. The subsequent restoration of which will be very, very problematic.

The purpose of this post is not any PR of repair shops, but I want to convey to you that sometimes self-repair can be more expensive than taking it to a professional workshop. Although, of course, this is your money and what is better or more risky is up to you.

If you nevertheless decide that you are able to independently repair the radio equipment, then when creating a post, be sure to indicate the full name of the device, modification, year of manufacture, country of origin and other detailed information. If there is a diagram, then attach it to the post or give a link to the source. Write down how long the symptoms have been manifesting, whether there were surges in the supply voltage network, whether there was a repair before that, what was done, what was checked, voltage measurements, oscillograms, etc.From a photo of a motherboard, as a rule, there is little sense, from a photo of a motherboard taken on a mobile phone there is no sense at all. Telepaths live in other forums.
Before creating a post, be sure to use the search on the forum and on the Internet. Read the relevant topics in the subsections, perhaps your problem is typical and has already been discussed. Be sure to read the article Repair strategy