Refinement of power supplies. Refinement of computer power supplies ATX, upgrading, improvement, improve reliability, reducing interference and ripples Improvement of the computer power supply

How to make a full-fledged power supply with a range of adjustable voltage 2.5-24 volts, it can be very simple, can repeat each without having a radio amateur experience.

We will do from the old computer unit, TX or ATH without a difference, good, over the years of the PC, each house has already accumulated enough of the old computer iron and the BP probably there is also there, therefore the cost of homemade will be insignificant, and for some masters equal to zero rubles .

I got for the alteration of which AT block.

The more powerful will be used by the BP, the better the result, my donor is only 250W with 10 ampere on the tire + 12V, and in fact, with a load of only 4 and it does not cope, there is a complete output drawdown.

See what is written on the case.

Therefore, look at what current you are planning to receive from your adjustable BP, such a donor potential and lay down immediately.

The options for finalizing the standard computer BP set, but they are all based on the change in the blocking of the IC-TL494CN chip (its analogues of DBL494, ka7500, IR3M02, A494, MV3759, M1114EU, MPC494C, etc.).

Figure No. 0 TL494CN chip and analogs.

Let's see several options The execution of computer BP schemes, perhaps one of them will be your and deal with the strapping will be much easier.

Scheme number 1.

We will start work.
First, it is necessary to disassemble the BP housing, unscrew the four bolts, remove the lid and look inside.

We are looking for on the board the chip from the list above, if it does not turn out to be, then you can search the version of the Internet for your IS.

In my case, the KA7500 chip was discovered on the board, which means you can begin to study the strapping and the location of unnecessary parts to us that you want to delete.

For the convenience of work, first completely unscrew the entire board and take out from the case.

In the photo 220V power connector.

Disconnect the power and fan, drop or whining the output wires so that you do not interfere with us to understand in the scheme, leave only the necessary, one yellow (+ 12V), black (general) and green * (Start ON) if there is such.

There is no green wire in my AT block, so it starts immediately when turning on the outlet. If the ATH block, then it should have a green wire, it must be soldered to the "common", and if you wish to make a separate power on the case, then simply put the switch to the break of this wire.

Now we need to look at how much Volts are weekend large capacitors, if less than 30V is written on them, then it is necessary to replace them with similar, only with a working voltage at least 30 volts.

In the photo - black capacitors as a replacement option for blue.

This is done because our final block will not give out +12 volts, but to +24 volts, and without replacing the capacitors will simply explode at the first 24V test, after a few minutes of work. When selecting a new electrolyte, it is not desirable to reduce the container, it is always recommended to increase.

The most responsible part of the work.
We will delete everything excess in the IC494 strapping, and solder other nominal details so that the result is such a blockage (Fig. No. 1).

Fig. №1 Change in the strapping of the IC 494 chip (refinement scheme).

We will need only these legs of chips №1, 2, 3, 4, 15 and 16, do not pay for other attention.

Fig. №2 Option of refinement on the example of scheme number 1

Decoding designations.

It is necessary to do about so, we find the leg number 1 (where the point is on the case) of the chip and study that it is connected to it, all chains must be removed, disconnect. Depending on how you have in a specific modification of the board, the tracks will be located and the parts are created, the optimal finalization option is selected, it can be dropping and lifting one feet of the part (breaking the chain) or it will be easier to cut the track with a knife. Deciding with the plan of action, we begin the process of reworking according to the refinement scheme.

In the photo - replacement of resistors to the desired nominal.

In the photo - raising the legs of unnecessary parts, tearing chains.

Some resistors who are already in the scheme of the strapping can approach without replacing them, for example, we need to put a resistor on R \u003d 2.7K with a connection to "common", but there is already a R \u003d 3K connected to "general", it is quite suitable for us. And we leave it there without change (an example in fig. No. 2, green resistors do not change).

On the picture- Curl tracks and added new jumpers, old nominal nominations are written by a marker, it may be necessary to restore everything back.

Thus, we look at and remake all the chains on six legs of the chip.

It was the most difficult point in the alteration.

We make voltage and current controls.

We carry out variable resistors on the 22k (voltage regulator) and 330Ω (current regulator), we solder two 15 cm wires to them, other ends are soldered according to the circuit (Fig. No. 1). Install on the front panel.

Voltage control and current.
For control, we will need a voltmeter (0-30V) and an ammeter (0-6a).

These devices can be purchased in Chinese online stores at the best price, my voltmeter cost me with the delivery of only 60 rubles. (Voltmeter :)

Ammeter I used my own, from the old stocks of the USSR.

IMPORTANT - inside the device there is a current resistor (current sensor), which we need according to the scheme (Fig. No. 1), therefore, if you use an ammeter, then the current resistor is additionally not necessary, it is necessary to install without an ammeter. Usually it is done homemade, the wire d \u003d 0.5-0.6 mm, the turn to the turn to the entire length is wound on the 2-won't resistance of MLT, the ends are screwed to the conclusions of the resistance, that's all.

The body of the device will be done for themselves.
You can leave completely metallic, cutting holes for regulators and control devices. I used the trimming of the laminate, they are easier to drill and cut down.

But the best of these BPs, unfortunately, is far from the ideal of "blocking". For example, the problem of "noise" sound card known to many when the power saving mode is on. Or another problem - accustomed to the old standard AT users at first negatively reacted to the need to separately turn off the system unit and monitor. Many were bought with such a necessity, part leaves the monitor constantly on, and part turns off the computer using a shared network filter.

That's the solution to these problems, we will fight in this part of the article. It should be recalled that any interference in the power supply is fraught with a guarantee loss, and especially difficult cases, and spurry equipment. So with any change, you must understand what you do, and be completely confident.

Voltage oscillograms with changing load have very noticeable ripples. That is this signal you hear in your columns. How can you get rid of it? Well, first, choose a power supply with the smallest pulsations. Or modify the existing one. For this, it is obvious that additional filtering containers must be added. The simplest and most convenient attack on the reverse side of the power supply board of a large number of inanctuous tanks.

Dimensions They are very small with a sufficient par value (1MKF), the price of them is low and almost anyone can afford to buy several dozen of such capacitors at a price close to the price of one - two bottles of beer. Let you not frighten the dimensions of capacitors in the photo. They are and a little more.

By attacking between the tracks with all the output voltages and the power of the power supply of these capacitors (if you look closely, everything becomes noticeable, and not only circled):

You can significantly reduce interference listened at the output of the sound card. In addition, a significant reduction in the level of high-frequency components in the output voltage extends the life of standard electrolyte power supply capacitors. Yes, and the stability of the computer work will not suffer from this ...

When attacking capacitors in the power supply, it is necessary to ensure that there are no closures between the tracks, which is powered and common tires.

Now consider how you can refine ATX power supply in order for it to independently turn on and disable the monitor when the computer is turned on.

Obviously, the most convenient option will be the installation of a relay of small dimensions, but sufficient switching power:

(These are now selling a lot in the nearest radio component store) to control the voltage to the monitor. You can save the control winding from +5 or from + 12V, depending on the relay applied. The inclusion scheme is as follows:

The diode is enabled in order to accumulated in the relay control coil energy, when the computer is turned off, the glass on it to the ground. The choice of diode is easy - any medium-high silicon diode. For example, KD105 or 1N40007. The resistor and the condenser are needed to prevent the spark when switching the monitor. The capacitor is selected with a rating of 0.05μF per 400V. Resistor - 1kom to 1W.

Here is the simplest scheme. It is extremely desirable to include a pair of control relays that open both network monitor wires. It is necessary because if your computer is turned on, where your computer is turned on, have a grounded contact (i.e., connected to zero network of power supply), then an option is possible when you blur with a relay exactly zero. And he, filed on the computer case (due to the very reassembly), will go along the earthen lines of the signal wires and the power on the monitor will not be removed. Will your signal wires sustain such a current? I doubt. So from sin away - put a couple of relays. At least, you can carry your computer and stick it into any socket, without concerning the grounding scheme.

Unfortunately, in most ATH Power Blocks connector for connecting the monitor (even uncontrollable) is usually absent. Therefore, you will have to take a drill, a hacksaw and a file, so that you can do the appropriate hole and put the connector on it (or purchased in the store).

Here you can see the riveted grille on the rear wall of the power supply. To improve the aesthetic perception, this hole can be covered with a wire lattice, which will be discussed in the second part of the article.

Now it remains only to connect the monitor to the resulting connector and enjoy it automatically turn on and off. However, in this case, a nuisance appears - in the case of replacing the old low-power BP on a new one (and it does not prevent modern glands at all), it becomes lazily to sleep. It is easier to replace the filling in the old package to take from the new power supply. But here is the full detriment for your brown fantasy.

I needed a lightweight power supply, for different cases (expeditions, nutrition of different kV and VHF transceivers or to move to another apartment not to carry with a transformer BP). After reading the available information on the network, about the alteration of computer BP - I realized that it would be necessary to deal with himself. I found everything, it was described by somehow calm and not quite understandable (for me). Here I will tell, in order, as I reworked several different blocks. Differences will be described separately. So, I found several BP from the old PC386 with a capacity of 200W (in any case, it was written on the lid). Usually, such as the following are written on the housings of such BP: + 5V / 20A, -5V / 500MA, + 12V / 8A, -12V / 500MA

The currents indicated over the tires +5 and + 12V are impulse. It is impossible to constantly load with such currents of BP, high-voltage transistors will also be tested. Take 25% from the maximum pulse current and get the current that the power supply can keep constantly, in this case it is 10a and up to 14-16a briefly (no more than 20s). Actually, it is necessary to clarify that 200W bp is different, there are those who came across not everyone could keep 20a even briefly! Many have dragged only 15a, and some up to 10a. Keep it in mind!

I want to note that the specific model of the BP role does not play, since all of them are made in almost one scheme with small variations. The most critical moment is the presence of the DBL494 chip or its analogues. I came across a BP with one microcircuit 494 and with two chips 7500 and 339. Everything else, it does not matter much. If you have the opportunity to choose BP from several, first of all, pay attention to the size of the pulse transformer (the bigger, the better) and the presence of a network filter. Well, when the network filter is already smoky, otherwise it will have to penetrate himself so that there is no interference. It is easy, wrap 10 turns on the ferrite ring and put two capacitors, the places for these parts are already provided on the board.

Priority modifications

To begin with, we will make some simple things, after which you will receive a well-working power supply with an output voltage of 13.8V, direct current up to 4 to 8a and short-term up to 12a. You will make sure that the BP works and decide whether to continue the modifications.

1. We disassemble the power supply and pull out the board from the housing and carefully clean it, brush and vacuum cleaner. Dust should not be. After that, we drop all the beams of the wires going to the tires +12, -12, +5 and -5v.

2. You need to find (on the board) DBL494 chip (in other boards costs 7,500, this is analog), switch the priority of protection from the tire + 5V to + 12V and install the voltage you need (13 - 14V).
From the 1st leg of the DBL494 chip departs two resistors (sometimes more, but it's not fundamentally), one goes to the housing, the other to the + 5B bus. He needs us, gently disappear one of his legs (break the connection).

3. Now, between the bus + 12V and the first knife chip DBL494 we solder a resistor 18 - 33k. You can put a stroke, set the voltage + 14V and then replace it with constant. I recommend installing not 13.8V, namely, on 14.0V, because most of the company square meters of equipment works better at this voltage.

Setup and adjustment

1. It's time to turn on our BP to check whether we did everything right. The fan can not be connected and the board itself does not insert into the housing. Turn onboard, without load, to the bus + 12V we connect a voltmeter and see what voltage is there. The trimming resistor, which stands between the first leg of the DBL494 chip and the + 12B china chip, set the voltage from 13.9 to + 14.0V.

2. Now check the voltage between the first and seventh feet of the DBL494 chip, it must be at least 2V and not more than 3B. If this is not the case, pick up the resistor resistance between the first leg and the housing and the first leg and the + 12V tire. Pay special attention to this item, this is a key point. At voltage above or below the specified, the power supply will work worse, unstable, to keep less load.

3. Rock up the thin wire of the tire + 12V on the body, the voltage should be the abyss so that it is restored - turn off the BP for a couple of minutes (It is necessary that the tanks are discharged) And turn on again. Voltage appeared? Okay! As you can see, protection works. What, not worked?! Then throw out this BP, it does not fit and take the other ... hee.

So, the first stage can be considered completed. Insert the board into the case, output the terminals for connecting the radio station. Power supply can be used! Connect the transceiver, but it is impossible to give the load of more than 12a! Automotive VHF station, will work at full power (50W)And in the kV transceiver will have to install 40-60% of power. What will happen if you load the BP with a big current? Nothing terrible, usually triggers protection and disappears the output voltage. If the defense does not work, high-voltage transistors overheat and burst. In this case, the voltage simply disappears and there will be no consequences for the equipment. After their replacement, the BP is operational again!

1. I turn over the fan on the contrary, it should blow inside the housing. Under the two fan screws, put the washers to deploy it slightly, and then blows only on high-voltage transistors, it is incorrectly, it is necessary that the air flow is directed to diode assemblies and on the ferrite ring.

Before that, the fan is preferably lubricated. If it is very noise, put a resistor 60 - 150Ω 2W resistor sequentially with it. Or make the rotational regulator depending on the heating of the radiators, but about it is slightly lower.

2. Display two terminals from BP to connect the transceiver. From the 12V bus to the terminal, run 5 wires from that beam which you dropped first. Between the terminals, place a non-polar capacitor for 1MKF and a LED with a resistor. Minus wire, also bring five wires to terminal.

In some BP, parallel to the terminals to which the transceiver is connected, put the resistor with resistance 300 - 560. This is the load, in order not to have triggered protection. The output chain should look something like that, as shown in the diagram.

3. Clean the tire + 12V and get rid of excess trash. Instead of diode assembly or two diodes (which often put instead of it), I put the 40cpq060, 30cpq045 or 30CTQ060 assembly, any other options will deteriorate efficiency. Nearby, on this radiator, it is an assembly of 5V, we drop it and throw it away.

Under the load, the following parts are most hot: two radiator, a pulse transformer, a throttle on a ferrite ring, choke on a ferrite rod. Now our task is to reduce the heat transfer and increase the maximum load current. As I said earlier, he can reach 16a (for BP power 200W).

4. Flow out the throttle on the ferrite rod from the bus + 5V and put it on the bus + 12V, which is previously the throttle (It is higher and wound with thin wire) Drop and throw away. Now the throttle to warm up almost will not be or will, but not so much. On some choke charges, it is simply no, you can do without it, but it is desirable that it was for better filtering of possible interference.

5. On a large ferrite ring, throttle to filter pulse interference is wound. The tire + 12V is wound on it with a thinner wire, and the tire + 5 in the most thick. Blow out gently this ring and swap winding places for tires + 12V and + 5V (or turn on all windings in parallel). Now the tire + 12V passes through this throttle, the thick wire. As a result, this throttle will heat up significantly less.

6. In BP, two radiator are installed, one for powerful high-voltage transistors, another, for diode assemblies by +5 and + 12V. I came across a few varieties of radiators. If, in your BP, the sizes of both radiators are 55x53x2mm and in the upper part they have edges (as in the photo) - you can count on 15a. When radiators have a smaller size - it is not recommended to load the BP current of more than 10a. When the radiators are thicker and have an additional platform at the top - you are lucky, it is the best option, you can get 20a for a minute. If small radiators, to improve heat transfer, can be fixed on them a small plate of duralumin or half from the radiator of the old processor. Please note that high-voltage transistors to the radiator are well screwed, sometimes they hang.

7. We drop electrolytic capacitors on the bus + 12V, they put 4700x25V in their place. Capacitors on the + 5B bus are desirable to fall, just to ensure that the places of free more and air blew air from the fan better.

8. On the board you see two high-voltage electrolytes, usually it is 220x200V. Replace them for two 680x350v, in the extreme case, connect parallel to two to 220 + 220 \u003d 440MKF. This is important and the matter is not only in filtration, impulse interference will be weakened and resistance to maximum loads will increase. The result can be viewed with an oscilloscope. In general, it must be done!

9. It is desirable that the fan changed the speed depending on the heating of the BP and did not spin when there is no load. It will extend the life to the fan and reduce noise. I offer two simple and reliable schemes. If you have a thermistor, see the scheme in the middle, the trimming resistor set the temperature of the thermistor of approximately + 40c. The transistor, you need to put the KT503 with a maximum current gain (this is important), other types of transistors work worse. The thermistor of any type of NTC, this means that when heated, its resistance should decrease. You can use a thermistor with another face value. The rapid resistor must be multiple, so easier and more accurately configure the fan response temperature. Fight with a scheme screw to the free fan's hand. The thermistor is fastened to the choke on the ferrite ring, it heats up faster and stronger than the rest of the parts. You can glue the thermistor to the diode assembly by 12V. It is important that none of the conclusions of the thermistor do not have a radiator !!! In some BP, there are fans with a lot of consumption current, in this case, after KT503, you need to put KT815.

If you do not have a thermistor, do the second scheme, see the right, two diodes d9 are used as a thermoelement. With transparent flasks, glue them to the radiator on which the diode assembly is installed. Depending on the transistors used, it is sometimes necessary to choose a resistor 75 com. When the BP works without load, the fan should not spin. Everything is simple and reliable!

Conclusion

From the computer power supply unit 200w, really get 10 - 12a (if there will be large transformers and radiators in the BP) With constant load and 16 - 18a briefly at an output voltage of 14.0V. This means that you can safely work in SSB and CW modes at full power (100W) transceiver. The SSTV, RTTY, MT63, MFSK and PSK modes will have to reduce the transmitter power to 30-70W., Depending on the duration of work on the transfer.

The weight of the converted BP, approximately 550g. It is convenient to take with you in radio applections and various trips.

When writing this article and during experiments, three BP were ruled (as you know, experience does not come immediately) And successfully redone the five BP.

A large plus computer BP is that it works stably when changing the mains voltage from 180 to 250V. Some copies work and with greater stress scattering.

See photos of successfully converted pulse power supplies:

Igor Lavrushov
Kislovodsk

The best option is the acquisition and use of a high-quality power supply. But if there is no possibility and / or there is a desire to improve the block you have already existed, then quite good results can be obtained when you refine a cheap (budget) power supply. Chinese designers tend to make printed circuit boards by the criterion of maximum versatility, i.e., so that, depending on the number of elements installed, it would be possible to vary with quality and, accordingly, the price.

Therefore, if you install those details on which the manufacturer saved, and something else to change - the unit of the average price category will be. Of course, it cannot be compared with expensive specimens, where the topology of printed circuit boards, circuitry, and all the details were originally calculated to obtain high quality.
But for the average computer, this is a completely acceptable option.

All you will do with your BP - you do at your own risk!

If you do not have enough qualifications, do not read what is written here and all the more do nothing!

First of all, you need to open the BP and evaluate the size of the largest transformer, if it has a tag, at which the numbers 33 or higher are at first and has dimensions of 3x3x3 cm and more - it makes sense to mess around. Otherwise, you hardly have to achieve an acceptable result.

In the photo 1 - a transformer of a normal power supply, in photo 2 - a transformer of a frank Chinese.

It should also be paid attention to the dimensions of group stabilization choke. The larger the size of the cores of the transformer and the choke, the greater the stock of saturation currents.
For the transformer, the falling into saturation is fraught with a sharp drop in the efficiency and the probability of failure of high-voltage keys, for the throttle - a strong spread of stresses in the main channels.

Fig. 1 Typical Chinese ATX power supply, no network filter.

The most critical items in the BP are:
Capacitors
. Volocked transistors
Equalized rectifier diodes
. High frequency power transformer
. Olight diode rectifier assemblies

Refinement:
1. For a start, it is necessary to replace the input electrolytic capacitors, change to the capacitors of a greater container that can fit on the seats. Usually in cheap blocks of their ratings 220μF x 200V or at best, 330μF x 200V. We change to 470μF x 200V or better at 680μF x 200V. These are condensed with a block's ability to keep the short-term disappearance of the network voltage and the power output by the power supply.

Fig. 2 Input electrolytic capacitors and high-voltage part of the power supply, including a rectifier, a half-lit-up inverter, electrolytes for 200V (330μF, 85 degrees).

Next, it is necessary to put all the chokes to the low-voltage part of the BP of the Method of the Network Filter (place for its installation).
These chokes can be coated on a ferrite ring with a diameter of 1-1.5 cm with a copper wire with a lacquer insulation by a cross section of 1.0-2.0 mm 10-15 turns. You can also take chossels from faulty BP. You still need to reconstruct smoothing capacitors to the empty places of the low-voltage part. Capacitance capacitors should be chosen maximum, but so that it can fit on a regular place.
It is usually enough to put 2200μF capacitors on 16V series ESR 105 degrees, in the chain + 3.3V, + 5V, + 12V.

In rectifier modules of secondary rectifiers, we replace all diodes to more powerful.
The power consumption of computers in recent times, to a greater extent increased over the tire + 12V (motherboards and processors), so first of all you need to pay attention to NaTOT module.

Typical view of straightening diodes:

1. - MBR3045PT (30a) diode assembly - are installed in expensive power supplies;

2. - UG18DCT (18a) diode assembly - less reliable;

3. - Diodes instead of assembly (5a) - the most unreliable version subject to mandatory replacement.

Channel + 5V StBy- The diode of the FR302 duty mode is changed to 1N5822. We also put the missing filtering choke, and the first filter condenser is increasing to 1000μF.

Channel + 3.3V - Assembly S10C45 Change on 20C40 (20A / 40V), to the existing capacity of 2200UF / 10V, add another 2200UF / 16V and the missing choke. If the channel + 3.3V is implemented on the bevel, then we put the transistor with a power of at least 40a / 50V (IRFZ48N).

Channel + 5V. - S16C45 diode assembly by 30c40s. Instead of 1000UF / 10V single electrolyte, we set 3300UF / 10V + 1500UF / 16V.

Channel + 12V. - Diode assembly F12C20 change to two in the UG18DCT parallel (18a / 200V) or F16C20 (16A / 200V). Instead of one condenser 1000UF / 16V, we put - 2pcs 2200μF / 16V.

Channel -12V. - instead of 470μF / 16V, we put 1000μF / 16V.

So, we put 2 or 3 diode assemblies of the MOSPEC S30D40 (digit after D - voltage - the more, the more calmer) or F12C20C - 200V and the same in the characteristics, 3 condenser 2200 μF x 16 volt, 2 of the condenser 470μF x 200V. Electrolytes, put only low-impedance from a series of 105 degrees! - 105 * p.

Fig. 3 low-voltage part of the power supply. Rectifiers, electrolytic capacitors and chokes, some are missing.

If the power supply radiators are made in the form of plates with cutting petals, weighed these petals in different directions to maximize their efficiency.

Fig. 5 ATX power supply with modified cooling radiators.

Further finalization of the BP is reduced to the following ... As is known in the BP channels +5 volts and +12 volts stabilize and manage simultaneously. With the +5 volt, the actual voltage on the +12 channel is 12.5 volts. If the computer is a strong load on the channel +5 (system based on AMD), then the voltage drops up to 4.8 volts, and the voltage over the channel +12 becomes 13 volt. In the case of the Pentium base system, the channel +12 volt is stronger and everything happens there on the contrary. Due to the fact that the +5 volt channel in BP is much better, then even a cheap block will be without any problems to feed the system based on AMD. Whereas Pentium power consumption is much more (especially by +12 volt) and cheap BP must be refined.
The overestimated voltage via channel 12 volts is very harmful for hard drives. Mostly heating HDD occurs due to increased voltage (more than 12.6 volts). In order to reduce the voltage of 13 volts, it is sufficient to break the yellow wire that feeds the HDD, to have a powerful diode, such as KD213. As a result, the voltage will decrease by 0.6 volts and will be 11.6 - 12.4V, which is quite safe for the hard disk.

As a result, upgrading, thus, a cheap ATX power supply, you can get a good BP for a home computer, which will be much less warm.

Hello, now I will tell about the alteration of the ATX power unit of the Codegen 300W 200xa model in the laboratory power supply with voltage adjustment from 0 to 24 volts, and the current limit from 0.1 a to 5 amps. I will lay out the scheme that I turned out, maybe someone will improve or add. The box itself looks like this, although the sticker may be blue or other color.

And the 200XA and 300x models and 300x boards are almost the same. Under the board, there is an inscription CG-13C, it can be CG-13A. Perhaps there are other models similar to this, but with other inscriptions.

Drop out unnecessary parts

Initially, the scheme looked like this:

It is necessary to remove everything unnecessary, the ATX wire connectors, dig and wind the unnecessary windings on the stabilization throttle group. Under the throttle on the board, where it is written +12 volts of that winding and leave, the rest are chatting. Sweep the braid from the board (the main power transformer), in no case bite it. Remove the radiator along with Schottky diodes, and after removing everything too much, it will look like this:

The ultimate scheme after rework, it will look like this:

In general, we drop all the wires, details.

Making Shunt

We make a shunt from which we will remove the voltage. The meaning of the shunt is that the voltage drop on it, says Shim-y on how loaded over the current - the output of the BP. For example, the spun resistance from us turned out 0.05 (OM), if you measure the voltage at the shunt at the time of passage 10 and then the voltage on it will be:

U \u003d I * R \u003d 10 * 0.05 \u003d 0.5 (volts)

I will not write about the manganin shunt, because I did not buy it and I did not have it, I used two tracks on the board itself, closing the tracks on the board as in the photo, to obtain Shunts. It is clear that it is better to use manganin, but also works more than normal.

Put choke L2 (if any) after Shunts

In general, it is necessary to count on, but if that - on the forum somewhere slipped the program for calculating chokes.

Apply a total minus on PWM

You can not serve if it is already ringing on the 7 leg of PWM. Just on some boards on 7 output there was no total minus after the smelting of parts (why - I do not know, I could not make mistakes that was not :)

Solder to 16 output PWM wire

We solder to 16 with PWM - wire, and this wire is supplying for 1 and 5 leg LM358

Between the 1st leg of PWM and the output plus, we solder the resistor

This resistor will limit the voltage issued by the BP. This resistor and R60 forms a voltage divider, which will share the output voltage and feed it to 1 leg.

OU (PWM) inputs on the 1st and 2nd legs with us serve to task the output voltage.

A task on the output voltage of BP comes to the 2nd leg, since 5 volts (VREF) can come to the second leg as possible, then the reverse voltage should come to the 1st leg also not more than 5 volts. For this, we need a voltage divider from 2 resistors, R60 and the one that we will install from the output of BP on 1 leg.

How it works: let's say the variable resistor put 2,5 volts on the second leg, then the PWM will produce such pulses (increase the output voltage from the power supply of the BP) until 2,5 (volts) will arrive at 1 foot. Suppose if this resistor is not, the power supply will be released on the maximum voltage, because there is no feedback from the OPP output. Nominal resistor 18.5 com.

We install condensers and load resistor

Load resistor can be supplied from 470 to 600 Ohm 2 watts. Capacitors 500 μF for voltage of 35 volts. I did not have capacitors with the required voltage, I installed 2 consistently 16 volts 1000 μF. We solder capacitors between 15-3 and 2-3 PWM feet.

Shipping a diode assembly

We put a diode assembly of the one that also stood 16C20C or 12C20C, this diode assembly is designed for 16 amps (12 amps, respectively), and 200 volts of reverse peak voltage. The diode assembly of 20c40 will not fit us - do not think to put it - it burns (checked :)).

If you have any other diode assemblies, see the reverse peak voltage was at least 100 V and on the current, which is more. Ordinary diodes will not fit - they burn, it is ultra-rapid diodes, just for a pulsed power supply.

Put a jumper to power PWM

Since we removed a piece of schema that was responsible for the power supply to PWM PSON, we need to power the PWM from the duty unit of the power supply 18 V. Actually, we install the jumper instead of the Q6 transistor.

Sold down the output of the power supply +

Then cut the total minus which goes to the case. We do so that the total minus does not touch the corps, otherwise the stroke plus, with the BP body, everything burns.

Solder wires, total minus and +5 volts, output of the BP duty

This voltage will be used to power the volt ammeter.

Solder wires, total minus and +18 volts to fan

This wire through a 58 ohm resistor will be used to power the fan. And the fan must be deployed so that it is blowing on the radiator.

Solder wire from the transformer braid to the total minus

Sold 2 Wires from Shunts for OU LM358

We solder wires, as well as resistors to them. These wires will go to the LM357 OU through resistors 47 ohms.

Solder wire to 4 legs shim

With a positive +5 volt voltage at this PWM input, it is limited to the regulation limit on C1 and C2 outputs, in this case, with an increase in the DT input, an increase in the filling coefficient on C1 and C2 (you need to see how the output transistors are connected). In a word - stop the exit of BP. This 4th input of PWM (let's give +5 c) we will use to stop the BP output in the case of KZ (above 4.5 A) at the output.

We collect current gain and protection against KZ

Attention: this is not a complete version - details, including photographs of the process of rework, look at the forum.

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