DIY asus laptop network adapter repair

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

It is about him that the conversation will go here. One not very wealthy friend recently stopped working the power supply for an acer laptop. 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 :). Immediately I give here several diagrams of power supplies - click to enlarge.

When the power supply is turned on, nothing happens - the LED does not light up and the voltmeter shows zero at the output. Checking the power cord with an ohmmeter gave nothing. We disassemble the case. Although it's easier said than done: there are no screws or screws provided here, 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. Do not overdo it, or cut the board!

After the case is slightly parted, we insert a flat screwdriver into the formed gap and with force we 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 anything black and charred.

The dialing of the input circuits of the 220V mains voltage revealed a malfunction - this is a self-healing fuse, which for some reason did not want to recover from an overload :)

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 power supply unit. The green LED lit up, indicating the presence of 19V, but there is still nothing on the connector. More precisely, sometimes something slips, as if the wire is bent.

We'll also have to repair the power supply cord to the laptop. Most often, a break occurs at the point where it is inserted into the case or at the power connector.

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

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

We solder the connectors back and carry out the tests. Everything worked - the repair is over.

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

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

In the event of a malfunction, many simply throw it away, and buy a universal power supply unit for laptops for 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 a power supply from an ASUS laptop. It is also an AC / DC power adapter. Model ADP-90CD... Output voltage 19V, maximum load current 4.74A.

The power supply itself was working, which was clear from the presence of a green LED indication. The voltage at the output plug corresponded to that 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 unit beeps. It became clear that the switching power supply was trying to start, but for some reason, either an overload or short-circuit protection was triggered.

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

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

Next, with a manual jigsaw, we cut into the depth of the body by 2-3 mm. in the middle of the body along the connecting seam. The cut must be done carefully. Overdoing it can damage the circuit board or electronics.

Then we take a flat screwdriver with a wide edge, insert it into the cut and unclip the halves of the case. There is no need to rush. When separating the halves of the case, a characteristic click should occur.

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

To inspect the elements on the printed circuit board, you will need to remove the aluminum radiator bar. In my case, the bar was attached to other parts of the radiator with latches, and was also glued to the transformer with some kind of silicone sealant. I managed to separate the bar from the transformer with a sharp blade of a pocket knife.

The photo shows the electronic filling of our block.

The fault itself did not take long to look for. Even before opening the case, I was doing test turns. After a couple of connections to the 220V network, something crackled inside the block and the green indicator indicating work was completely extinguished.

When inspecting the case, a 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 unit ceased to function normally due to the fact that the electrolytic capacitor 120 uF * 420V “slammed” due to exceeding the operating voltage in the 220V power grid. Quite an ordinary and widespread malfunction.

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

The safety valve at the top of the housing is "swollen" - this is a sure sign of a defective condenser.

Here's another example with a faulty capacitor. This is a different laptop power adapter. Pay attention to the protective notch on the top of the condenser housing. It broke open from the pressure of the boiling electrolyte.

In most cases, bringing the PSU back to life is pretty 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 a 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 if you consider that the power supply case is compact and not ventilated, then the temperature inside it can be very high.

Long-term heating is very bad for the reliability of electrolytic capacitors. Therefore, I installed a Jamicon capacitor with a capacity of 68 μF * 450V, which is designed for operating temperatures up to 105 0 С.

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

In the process of repairing laptop power supplies, I encountered the fact that it is very difficult to find a replacement for the capacitor. And the point is not at all in the 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 of suitable size, albeit 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 sealing a new electrolytic capacitor, you must strictly observe the polarity connect the pins! Typically, the PCB has a “+" or "–“. In addition, a minus can be marked with a black bold line or a mark in the form of a spot.

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

When turning on for the first time after repair, keep a distance from the power supply, because if the polarity of the connection is reversed, the capacitor will "pop" again. This can cause the electrolyte to get into the eyes. This is extremely dangerous! Wear protective goggles if possible.

And now I’ll tell you about the "rake" that it is better not to step on.

Before you change anything, 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 slams, the electrolyte inside it breaks out under great pressure in the form of splashes and steam. It, in turn, instantly condenses on the nearby parts, as well as on the elements of the aluminum radiator.

Since the installation 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 electric current well. I was convinced of this from my own experience. And although I cleaned the power supply very carefully, I did not begin to solder the choke 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, it turned out that the remaining electrolyte under the throttle closed the circuit. The fuse has blown because of this. T3.15A 250V on the input circuit 220V. In addition, in the place of the short circuit, everything was covered with soot, and the wire of the choke burned out, which connected its screen and the common wire on the printed circuit board.

The same choke. The burned-out wire was restored.

Soot from a short on the printed circuit board just below the choke.

As you can see, it jumped out decently.

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 this is what he has inside. It can be easily disassembled, you just need to squeeze 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 your own. Then assemble the fuse.

Someone will say that this is a "bug". But I disagree. In the event of a short circuit, the thinnest wire in the circuit burns out. Sometimes even the copper tracks on the PCB will burn out. So in which case our self-made fuse will do its job. Of course, you can also do with a thin wire jumper by soldering it to the contact dimes on the board.

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

As you can see, liquid electrolyte can also remain under coil products, such as chokes. Even if it dries out, in the future, due to it, corrosion of the leads may begin. An illustrative example is in front of you. Due to electrolyte residues, one of the capacitor leads in the input filter completely corroded and fell off. This is one of the power adapters from the laptop that I have been repaired.

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

I must say that this is a very time-consuming business. First.

The PSU cooling heatsink consists of multiple aluminum fins. Between themselves, they are fastened with latches, and are also glued with something resembling a silicone sealant. It can be removed with a pocket knife.

The upper radiator cover is fastened to the main part with latches.

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

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 melt glue to glue the two plastic halves together. Since I don't have a thermal 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 he heated pieces of hot melt glue with a hair dryer until they melted. I removed the excess glue with a toothpick and once again blew it with a hairdryer on the soldering station.

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

Despite this, it turned out very soundly.

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 circuit in the choke output in the line filter circuit. Here is a photo.

It would seem that the matter is trifling, I rewound the coil and sealed it in place. But it takes a lot of time to find such a malfunction. It is not possible to detect it immediately.

Surely you have already noticed that large-sized elements, like 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 is clear that with its help large parts are fixed, which can fall off from shaking and vibrations, like this very choke, 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 pulsed 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, but also quite powerful. Typically, the wattage of power adapters is 40

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

It is not even possible to find a datasheet for a specific microcircuit. 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 overwhelming majority of laptop power adapters are made of very high quality. This can be seen at least by the presence of winding parts and chokes that are installed in the network filter circuit. It suppresses electromagnetic interference. In some low-quality power supplies from stationary PCs, such elements may be absent altogether.

The ADP-90YD power supply unit from an ASUS laptop was brought in for repair. It charges the laptop, then it doesn't. Unplug it from the socket, plug it in like normal, maybe something goes off.

I plug it into the network, check it with a tester that 19.35 V is there, I moved the wires and began to fall smoothly, as if the capacity was discharging, but maybe it was moving away. It is necessary to open the power supply unit. I inserted the knife into the joint of 2 halves of the case, gently tapped the knife with a hammer, the case and opened.

The board is in three layers of screens. All soldered, removed. The power supply is plump, and a lot of sealant is also poured.

A cursory examination revealed a torn-off leg of the filtering choke along the 220 V input circuit. "This is what 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 hammering with a hammer on the power supply housing, 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 finally discharged and the power supply unit 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 collected a small load from 5 watt resistors, the current consumption was only 0.07 A and the power supply unit started up normally. It's not clear at all ... but does the current consumption of the laptop mean not enough for him? I didn't want to, but I would have to go online, remove all the sealant to check everything.

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

An internet search returned the following:

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

Indeed, the voltage across the network capacitance is 496 V, everything fell into place. Such a voltage at idle is very high, the PWM controller sees it and goes into protection, and if you turn off the mains voltage, then the capacity gradually discharges, reaching normal values ​​and the power supply starts up for a short time. This is where 19 V came from if you turn off 220 V. And when I started the power supply unit even under a small load, the voltage did not jump so much and the PWM did not go into protection.

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

But it became interesting where almost 500 V came from on the hot side of the power supply and what does this have to do with these two capacities. The Internet helped again, I didn't want to pick out the entire power supply unit in search of an answer. The information was found on the forum, the phrase clarified everything:

There is a passive power corrector. in case of failure of metal-paper capacitors in the corrector circuit, and the corrector goes into spacing, 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 containers, but everything is not so simple here either.

The Chinese had containers with such a rating and dimensions, but we do not. 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 room 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 high-quality product, which is why they were out of order. I had to choose by size. The right-hand tank was a good fit, but it was 330 nF 400 V, so we had to install them.

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

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

Laptop power supplies. Scheme.

Schematic diagrams of laptop power supplies

Any craftsman who is faced with the repair of electronic equipment is faced with difficulties due to the lack of schematic diagrams, and it is not always possible to find the one you need on the Internet.

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

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

Schematic diagram of the power supply unit of the laptop LITEON 19V 3.42A:

Schematic diagram of the power supply unit of the laptop ADP-90SВ VV 19V 4.74A:

Schematic diagram of the power supply unit of the laptop ADP-36EN 12V 3A:

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

And one more power supply circuit, unfortunately its brand is not known, but maybe someone will come in handy:

We hope you find this article helpful. An archive with diagrams is available for download.

More notebook power supply diagrams in the articles:

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

Before taking up the tools and getting down 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 power supply unit at home. Without proper understanding, you can do more harm to the component, as well as your health!

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

• The problem is in the cable. In this case, performance is disrupted due to a break in the wiring or because of 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 have forgotten about the wires, then you risk getting acquainted with the plug pulled out from the laptop socket.
• The problem is in the power supply element. This damage can result from power surges, short circuits and mechanical damage.

If any of the points are familiar to you firsthand, then you can familiarize yourself with repairing 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 at least a little electrical diagrams, then you can safely take on the restoration work of the adapter. Let's take a look at two of the most common causes of breakdowns.

Do-it-yourself laptop power supply 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 yourself a thin blade or flat screwdriver. Find the longitudinal seam on the body of the device and slide the selected tool into the gap between the halves. Use a little force and carefully separate the body parts.
2. Now you can start extracting the "filling", 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 full extent of the breakdown. For the next part of the repair, you will need to get a diagram of your power supply unit, on which all circuit elements and their parameters will be marked.
4. The next step is to identify the broken element and carefully dismantle it with a soldering iron.To replace the old one, you will need a new serviceable part, which must fully meet 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 power supply unit.
5. If the glue is dry, you can charge your laptop using the repaired unit.

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

How to fix a laptop power supply if all the components inside the case are working properly? 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 goes from the PSU.
• Strip 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.

• To avoid short circuits, insulate the connected elements.
• Now plug the charger into your laptop and plug it into a power outlet.

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