Do-it-yourself asus laptop network adapter repair

When buying a laptop or netbook, more accurately calculating the budget for this acquisition, we do not take into account further related costs. The laptop itself costs, say, $500, but another bag is $20, a mouse is $10. When replacing a battery (and its warranty life is only a couple of years), it will cost $ 100, and the power supply will cost the same amount if it burns out.

It is about him that the conversation will go here. One not very wealthy friend, the power supply for an acer laptop has recently stopped working. You will have to pay almost a hundred dollars for a new one, so it would be quite logical to try to fix it yourself. The PSU itself is a traditional black plastic box with an electronic pulse converter inside, providing a voltage of 19V at a current of 3A. This is the standard for most laptops and the only difference between them is the power plug :). I immediately give here several power supply circuits - click to enlarge.

When you turn on the power supply to the network, nothing happens - the LED does not light up and the voltmeter shows zero at the output. Checking the power cord with an ohmmeter did not give anything. We disassemble the body. Although it’s easier said than done: there are no screws or screws, so we’ll break it! To do this, you need to put a knife on the connecting seam and hit it lightly with a hammer. Look, do not overdo it, otherwise you will cut the board!

After the case slightly diverges, we insert a flat screwdriver into the gap formed and forcefully draw along the contour of the connection of the halves of the case, gently breaking it along the seam.

Having disassembled the case, we check the board and parts for something black and charred.

The continuity of the input circuits of the 220V mains voltage immediately revealed a malfunction - this is a self-restoring fuse, which for some reason did not want to recover when overloaded :)

We replace it with a similar one, or with a simple fusible one with a current of 3 amperes and check the operation of the PSU. The green LED lit up, indicating the presence of a voltage of 19V, but there is still nothing on the connector. More precisely, sometimes something slips, like when a wire is bent.

You will also have to repair the cord connecting the power supply to the laptop. Most often, a break occurs at the point of its entry into the case or at the power connector.

We cut off at the body first - no luck. Now near the plug that is inserted into the laptop - again there is no contact!

A hard case is a break somewhere in the middle. The easiest option is to cut the cord in half and leave the working half, and throw out the non-working one. And so he did.

Solder the connectors back and test. Everything worked - the repair is completed.

It remains only to glue the halves of the case with “moment” glue and give the power supply to the customer. The entire repair of the PSU took no more than an hour.

An ordinary laptop power supply is a very compact and fairly powerful switching power supply.

In the event of a malfunction, many simply throw it away, and buy a universal PSU for laptops as a replacement, the cost of which starts from 1000 rubles. But in most cases, you can fix such a block with your own hands.

It's about repairing the power supply from an ASUS laptop. It's an AC/DC power adapter. Model ADP-90CD. Output voltage 19V, maximum load current 4.74A.

The power supply itself worked, which was clear from the presence of a green LED indication. The voltage at the output plug corresponded to what is indicated on the label - 19V.

There was no break in the connecting wires or breakage of the plug.But when the power supply was connected to the laptop, the battery did not start charging, and the green indicator on its case went out and glowed at half the original brightness.

It was also heard that the block beeps. It became clear that the switching power supply was trying to start, but for some reason either an overload occurs, or the short circuit protection is triggered.

A few words about how you can open the case of such a power supply. It is no secret that it is made airtight, and the design itself does not involve disassembly. To do this, we need several tools.

We take a manual jigsaw or a canvas from it. It is better to take a canvas for metal with a fine tooth. The power supply itself is best clamped in a vice. If they are not, then you can contrive and do without them.

Next, with a manual jigsaw, we make a cut deep into the body by 2-3 mm. in the middle of the body along the connecting seam. The cut must be done carefully. If you overdo it, you can damage the printed circuit board or electronic stuffing.

Then we take a flat screwdriver with a wide edge, insert it into the cut and split the body halves. No need to hurry. When separating the halves of the body, a characteristic click should occur.

After the power supply housing is opened, we remove the plastic dust with a brush or brush, we take out the electronic filling.

To inspect the elements on the printed circuit board, you will need to remove the aluminum heat sink bar. In my case, the bar was fastened to other parts of the radiator with snaps, and was also glued to the transformer with something like silicone sealant. I managed to separate the bar from the transformer with a sharp blade of a penknife.

The photo shows the electronic filling of our block.

It didn't take long to find the problem. Even before opening the case, I did test inclusions. After a couple of connections to the 220V network, something crackled inside the unit and the green indicator, signaling the operation, completely went out.

When examining the case, liquid electrolyte was found, which leaked into the gap between the network connector and the elements of the case. It became clear that the power supply stopped functioning properly due to the fact that the electrolytic capacitor 120 uF * 420V “slammed” due to the excess of the operating voltage in the mains 220V. Pretty common and widespread problem.

When dismantling the capacitor, its outer shell crumbled. Apparently lost its properties due to prolonged heating.

The safety valve at the top of the case is "bulging", a sure sign of a failed capacitor.

Here is another example with a faulty capacitor. This is another laptop power adapter. Pay attention to the protective notch in the upper part of the capacitor case. It opened from the pressure of the boiled electrolyte.

In most cases, bringing the power supply back to life is quite easy. First you need to replace the main culprit of the breakdown.

At that time, I had two suitable capacitors at hand. I decided not to install the SAMWHA 82 uF * 450V capacitor, although it was ideally sized.

The fact is that its maximum operating temperature is +85 0 C. It is indicated on its body. And given that the power supply housing is compact and not ventilated, the temperature inside it can be very high.

Prolonged heating has a very bad effect on the reliability of electrolytic capacitors. Therefore, I installed a Jamicon capacitor with a capacity of 68 uF * 450V, which is rated for operating temperatures up to 105 0 C.

It is worth considering that the capacitance of the native capacitor is 120 microfarads, and the operating voltage is 420V. But I had to put a capacitor with a smaller capacity.

In the process of repairing power supplies from laptops, I encountered the fact that it is very difficult to find a replacement for the capacitor. And the point is not at all in capacity or operating voltage, but in its dimensions.

Finding a suitable capacitor that would fit into a cramped case proved to be a daunting task.Therefore, it was decided to install a product that is suitable in size, albeit with a smaller capacity. The main thing is that the capacitor itself is new, of high quality and with an operating voltage of at least 420

450V. As it turned out, even with such capacitors, the power supplies work properly.

When soldering a new electrolytic capacitor, strictly observe the polarity terminal connections! As a rule, on the printed circuit board, next to the hole, there is a sign “+" or "–“. In addition, the minus can be marked with a black thick line or a mark in the form of a spot.

On the capacitor case on the side of the negative terminal there is a mark in the form of a strip with a minus sign “–“.

When you turn it on for the first time after repair, keep a distance from the power supply, because if you reverse the polarity of the connection, the capacitor will “pop” again. The electrolyte may get into the eyes. This is extremely dangerous! If possible, wear protective goggles.

And now I’ll tell you about the “rake”, which is better not to step on.

Before changing something, you need to thoroughly clean the board and circuit elements from liquid electrolyte. This is not a pleasant occupation.

The fact is that when an electrolytic capacitor pops, the electrolyte inside it breaks out under great pressure in the form of spray and steam. It, in turn, instantly condenses on the adjacent parts, as well as on the elements of the aluminum radiator.

Since the mounting of the elements is very tight, and the case itself is small, the electrolyte gets into the most inaccessible places.

Of course, you can cheat and not clean out all the electrolyte, but this is fraught with problems. The trick is that the electrolyte conducts electricity well. I have seen this from my own experience. And although I cleaned the power supply very carefully, I didn’t solder the throttle and clean the surface under it, I hurried.

As a result, after the power supply was assembled and connected to the mains, it worked properly. But after a minute or two, something crackled inside the case, and the power indicator went out.

After opening, it turned out that the remains of the electrolyte under the throttle closed the circuit. This caused the fuse to blow. T3.15A 250V on the input circuit 220V. In addition, everything was covered with soot at the short circuit, and the wire that connected its screen and the common wire on the printed circuit board burned out at the throttle.

The same throttle. Burnt wire repaired.

Short circuit soot on the PCB just below the throttle.

As you can see, it hit pretty hard.

The first time I replaced the fuse with a new one from a similar power supply. But when it burned down a second time, I decided to restore it. This is what the fuse looks like on the board.

And here's what's inside. He himself is easily disassembled, you just need to press the latches at the bottom of the case and remove the cover.

To restore it, you need to remove the remnants of the burnt wire and the remnants of the insulating tube. Take a thin wire and solder it in place of the native. Then assemble the fuse.

Someone will say that this is a "bug". But I don't agree. In the event of a short circuit, the thinnest wire in the circuit burns out. Sometimes even the copper tracks on the printed circuit board burn out. So in which case our self-made fuse will do its job. Of course, you can get by with a thin wire jumper by soldering it onto the contact pads on the board.

In some cases, to clean out all the electrolyte, it may be necessary to remove the cooling radiators, and with them active elements such as MOSFETs and dual diodes.

As you can see, liquid electrolyte can also remain under winding products, such as chokes. Even if it dries, then in the future, because of it, corrosion of the terminals may begin. A good example is in front of you. Due to electrolyte residues, one of the capacitor terminals in the input filter completely corroded and fell off. This is one of the laptop power adapters that I had for repair.

Let's go back to our power supply.After cleaning from electrolyte residues and replacing the capacitor, it is necessary to check it without connecting it to the laptop. Measure the output voltage at the output plug. If everything is in order, then we assemble the power adapter.

Needless to say, this is a very difficult task. First.

The cooling radiator of the power supply consists of several aluminum plates. Between themselves, they are fastened with latches, and also glued with something resembling silicone sealant. It can be removed with a penknife.

The upper radiator cap is attached to the main body with latches.

The bottom plate of the heatsink is fixed to the printed circuit board by soldering, usually in one or two places. An insulating plastic plate is placed between it and the printed circuit board.

A few words about how to fasten the two halves of the body, which at the very beginning we sawed with a jigsaw.

In the simplest case, you can simply assemble the power supply and wrap the halves of the case with electrical tape. But this is not the best option.

I used hot glue to glue the two plastic halves together. Since I don’t have a hot-melt gun, I cut off pieces of hot-melt glue from the tube with a knife and put them in the grooves. After that, I took a hot air soldering station, set about 200 degrees

250 0 C. Then I heated the pieces of hot glue with a hair dryer until they melted. I removed the excess glue with a toothpick and once again blew it with a soldering station hairdryer.

It is advisable not to overheat the plastic and generally avoid excessive heating of foreign parts. In my case, for example, the plastic of the case began to lighten with strong heating.

Despite this, it turned out very well.

Now I will say a few words about other malfunctions.

In addition to such simple breakdowns as a slammed capacitor or an open in the connecting wires, there are also such as an open inductor output in the line filter circuit. Here is a photo.

It would seem that it is a trifling matter, unwound the coil and soldered it into place. But it takes a lot of time to find such a malfunction. It is not immediately possible to find it.

Surely you have already noticed that large-sized elements, such as the same electrolytic capacitor, filter chokes and some other parts, are smeared with something like a white sealant. It would seem, why is it needed? And now it’s clear that with its help large parts are fixed, which can fall off from shaking and vibrations, like this very throttle, which is shown in the photo.

By the way, initially it was not securely fixed. Chatted - chatted, and fell off, taking the life of another power supply from the laptop.

I suspect that thousands of compact and rather powerful power supplies are sent to the landfill from such banal breakdowns!

For a radio amateur, such a switching power supply with an output voltage of 19 - 20 volts and a load current of 3-4 amperes is just a godsend! Not only is it very compact, it is also quite powerful. Typically, power adapters are rated at 40

Unfortunately, with more serious malfunctions, such as the failure of electronic components on a printed circuit board, the repair is complicated by the fact that it is quite difficult to find a replacement for the same PWM controller chip.

I can't even find a datasheet for a specific chip. Among other things, the repair is complicated by the abundance of SMD components, the marking of which is either difficult to read or it is impossible to purchase a replacement element.

It is worth noting that the vast majority of laptop power adapters are made very high quality. This can be seen at least by the presence of winding parts and chokes that are installed in the surge protector circuit. It suppresses electromagnetic interference. In some low-quality power supplies from stationary PCs, such elements may not be available at all.

They brought the ADP-90YD power supply from an ASUS laptop for repair. Either it charges the laptop or it doesn't. You take it out of the socket, you insert it like normal, maybe something is moving away.

I plug it into the network, I check 19.35 V with a tester, I moved the wires, it began to fall smoothly, as if the capacity was discharging, well, maybe it’s leaving. You need to open the power supply. He inserted the knife into the joint of 2 halves of the body, gently tapped the knife with a hammer, the body opened.

Board in three layers of screens. Soldered everything, took it off. The power supply is plump, and a lot of sealant is also poured.

During a cursory examination, a torn off leg of the filtering inductor was found along the 220 V input circuit. “Here it was that caused such a strange voltage drop,” I thought. I restored the throttle, I check - the result is the same. When 19.35 V is turned on, after 1 second it begins to smoothly fall to zero. Apparently from my swotting with a hammer on the PSU case, the throttle fell off. But here's what I noticed, if you turn off the power supply from the 220 V network, after a few seconds, 19.35 V appears at the output and even the charge lamp lights up on the laptop, but then the network capacity is completely discharged and the PSU turns off. It is very strange, apparently some kind of protection is triggered and does not allow the power supply to work, but what is the reason ...?

I assembled a small load from 5 watt resistors, the current consumption was only 0.07 A and the power supply started up normally. It’s not clear at all ... but does the laptop’s current consumption mean it’s not enough for him? I didn’t want to, but I’ll have to surf the Internet, remove all the sealant in order to check everything.

I measured the PWM controller, the protection obviously worked there, but the protection turned off when the network capacity started to discharge, but I was not even twitched to check the voltage on it.

An internet search turned up the following:

check the voltage on the mains electrolyte if it is more than 450 V (and where are there so many?), urgently change 2 film capacitors 474 nF 450 V and you will be happy

So it is, the voltage on the mains capacity is 496 V, everything fell into place. Such an idle voltage is very high, the PWM controller sees this and goes into protection, and if the mains voltage is turned off, the capacity is smoothly discharged, reaching normal values ​​and the power supply starts up for a short time. That's where 19 V came from if you turned off 220 V. And when I started the PSU even under a small load, the voltage did not jump up like that and the PWM did not go into protection.

It was possible to finish this, to replace the film containers, with which, as it turned out, there were serious problems.

But it became interesting where almost 500 V came from on the hot side of the power supply and where did these two capacities come from. The Internet helped again, I did not want to open the entire BP in search of an answer. Information found on the forum, everything was explained by the phrase:

There is a passive power corrector. if the metal-paper capacitors in the corrector circuit fail, and the corrector goes into overdrive, the voltage on the network bank drops above 500 volts. Therefore, if you just replaced the network bank, then it will not work for long. It is necessary to bring the voltage of the corrector back to normal or completely eliminate it.

It remains to buy and replace the containers, but here, too, not everything is so simple.

The Chinese had containers with such a denomination and dimensions, but we don’t. There were only 400 or 600 V. More - no less, but the left capacitance is just 474 nF 600 V, but how to put it in instead of those in the middle. There is not so much space there, and at 400 V it was no less in size. Moreover, the sellers assured that in such small dimensions, the Chinese were unlikely to be able to shove a quality one, which is why they failed. I had to choose the size. The right tank was well suited in size, but it was 330 nF 400 V, so I had to install them.

After installing new capacitors, the power supply immediately started up, the voltage stabilized, and there were no more problems with powering and charging the laptop.

The power supply is again wrapped in its screens, the case is glued together and returned to the customer.

Laptop power supplies. Scheme.

Schematic diagrams of laptop power supplies

Any master who is faced with the repair of electronic equipment faces difficulties due to the lack of circuit diagrams, and it is not always possible to find the right one on the Internet.

In this article, we want to share with you the schematic diagrams of some laptop power supplies, for sure they will be useful when repairing these devices.

The following image shows a schematic diagram of a Chinese-made power supply China Hp 19V 3.16A:

Schematic diagram of the laptop PSU LITEON 19V 3.42A:

Schematic diagram of the PSU laptop ADR-90SB VV 19V 4.74A:

Schematic diagram of the PSU laptop ADP-36EN 12V 3A:

The following diagram of the power supply DELL PA-1900-02 SMPS ADAPTÖR 19.5V 4.62A:

And one more power supply circuit, unfortunately its brand is not known, but it may come in handy for someone:

We hope that the article will be useful to you. The archive with schemes is available for download.

More laptop power supply diagrams in the articles:

Often in technology, the power adapter breaks. Typically, a laptop power supply becomes unusable due to incorrect use or a sharp surge in the voltage amplitude in the power supply. If you find a lack of power in this charging component, you can immediately use the services of a service center or even buy yourself a brand new device. Both options are unlikely to cost you cheap, and who likes extra costs? You can try to restore the former performance of the PSU yourself. Let's take a step-by-step look at repairing a laptop power supply today and pay attention to the main nuances.

Before you take up the tools and get to work, you should evaluate your abilities in this area several times.

Important! If you do not have basic skills in working with electrical appliances, we recommend that you refuse to repair the PSU at home. Without proper understanding, you can cause more harm to the component, as well as to your health!

You can immediately identify several of the most common types of faults:

• The problem is in the cable. In this case, the performance is impaired due to a break in the wiring or due to its crease. Such damage can be caused by pets who are very fond of chewing on something.
• The problem is in the connector. If you decide to move your device from one room to another and forget about the wires, then you run the risk of getting acquainted with the torn plug from the laptop socket.
• The problem is in the power supply unit. These damages can occur due to power surges, short circuits and mechanical damage.

If any of the points is familiar to you firsthand, then you can familiarize yourself with the repair of a laptop power supply with your own hands step by step and take the initiative into your own hands.

If you have ever held a soldering iron in your hands and know how to read electrical circuit diagrams at least a little, then you can safely take on the restoration work of the adapter. Let's look at the two most common causes of breakdowns.

Do-it-yourself laptop PSU repair is carried out as follows:

1. In order to bring the electronic converter back to life, it is necessary to start by opening the plastic case. To do this, you will need to get a thin blade or a flat screwdriver. Find the longitudinal seam on the body of the device and insert the selected tool into the gap between the halves. Apply a little force and carefully separate the parts of the case.
2. Now you can start extracting the “stuffing”, which is usually covered with plates made of metal. You will need to carefully remove or unsolder these plates.
3. After these steps, you will already be able to assess the extent of the breakdown. To carry out the next part of the repair, you will need to get a diagram of your PSU, on which all the elements of the circuit and their parameters will be marked.
4. Next, you have to determine the broken element and carefully dismantle it with a soldering iron.To replace the old one, a new serviceable part will be required, which must fully satisfy the characteristics of the chain. Solder the new component to the circuit and install the board back into the device case, remembering to carefully glue both parts of the PSU.
5. If the glue is dry, you can charge your laptop using the repaired block.

Important! If you think that this procedure is very complicated, then we do not recommend that you undertake the work yourself. Better - get a new adapter.

How to fix a laptop power supply if all the components inside the case are working? You can find the answer below.

The cord that comes from the power supply often suffers from various mechanical influences. If the problem lies in the wiring, then you can resort to the following instructions for carrying out restoration work:

• Cut off the wire that comes from the PSU.
• Clean up the wiring.
• Get a new plug. Next, cut the cable and screw the plug parallel to the center wire.
• Use a special technical hair dryer to solder the junction of the elements. Also, no one forbids you to use electrical tape or heat shrink tubing.

Important! If you want to use the latter, we recommend that you put this component on your cord in advance.

• In order to avoid short circuits, insulate the connected elements.
• Now plug the charger into your laptop and connect it to the mains.

back to content ↑