This page contains several dozen electrical circuit diagrams and useful links to resources related to the topic of equipment repair. Mainly computer. Remembering how much effort and time sometimes had to be spent searching for the necessary information, a reference book or a diagram, I have collected here almost everything that I used during repairs and that was available in electronic form. I hope this is of some use to someone.
Utilities and reference books.
The program is designed to determine the capacitance of a capacitor by color marking (12 types of capacitors).
startcopy.ru - in my opinion, this is one of the best sites on the RuNet dedicated to the repair of printers, copiers, and multifunctional devices. You can find techniques and recommendations for fixing almost any problem with any printer.
Power supplies.
Power supply circuits for ATX 250 SG6105, IW-P300A2, and 2 circuits of unknown origin.
NUITEK (COLORS iT) 330U power supply circuit.
Codegen 250w mod power supply circuit. 200XA1 mod. 250XA1.
Codegen 300w mod power supply circuit. 300X.
PSU diagram Delta Electronics Inc. model DPS-200-59 H REV:00.
PSU diagram Delta Electronics Inc. model DPS-260-2A.
DTK PTP-2038 200W power supply circuit.
Power supply diagram FSP Group Inc. model FSP145-60SP.
Green Tech power supply diagram. model MAV-300W-P4.
Power supply circuits HIPER HPU-4K580
Power supply diagram SIRTEC INTERNATIONAL CO. LTD. HPC-360-302 DF REV:C0
Power supply diagram SIRTEC INTERNATIONAL CO. LTD. HPC-420-302 DF REV:C0
Power supply circuits INWIN IW-P300A2-0 R1.2.
INWIN IW-P300A3-1 Powerman power supply diagrams.
JNC Computer Co. LTD LC-B250ATX
JNC Computer Co. LTD. SY-300ATX power supply diagram
Presumably manufactured by JNC Computer Co. LTD. Power supply SY-300ATX. The diagram is hand-drawn, comments and recommendations for improvement.
Power supply circuits Key Mouse Electronics Co Ltd model PM-230W
Power supply circuits Power Master model LP-8 ver 2.03 230W (AP-5-E v1.1).
Power supply circuits Power Master model FA-5-2 ver 3.2 250W.
Maxpower PX-300W power supply circuit
A good laboratory power supply is quite expensive and not all radio amateurs can afford it.
Nevertheless, at home you can assemble a power supply with good characteristics, which can cope well with providing power to various amateur radio designs, and can also serve as a charger for various batteries.
Such power supplies are assembled by radio amateurs, usually from , which are available and cheap everywhere.
In this article, little attention is paid to the conversion of the ATX itself, since converting a computer power supply for a radio amateur of average qualification into a laboratory one, or for some other purpose, is usually not difficult, but beginning radio amateurs have many questions about this. Basically, what parts in the power supply need to be removed, what parts should be left, what should be added in order to turn such a power supply into an adjustable one, and so on.
Especially for such radio amateurs, in this article I want to talk in detail about converting ATX computer power supplies into regulated power supplies, which can be used both as a laboratory power supply and as a charger.
For the modification, we will need a working ATX power supply, which is made on a TL494 PWM controller or its analogues.
The power supply circuits on such controllers, in principle, do not differ much from each other and are all basically similar. The power of the power supply should not be less than that which you plan to remove from the converted unit in the future.
Let's look at a typical ATX power supply circuit with a power of 250 W. For Codegen power supplies, the circuit is almost no different from this one.
The circuits of all such power supplies consist of a high-voltage and low-voltage part. In the picture of the power supply printed circuit board (below) from the track side, the high-voltage part is separated from the low-voltage part by a wide empty strip (without tracks), and is located on the right (it is smaller in size). We will not touch it, but will work only with the low-voltage part.
This is my board and using its example I will show you an option for converting an ATX power supply.
The low-voltage part of the circuit we are considering consists of a TL494 PWM controller, an operational amplifier circuit that controls the output voltages of the power supply, and if they do not match, it gives a signal to the 4th leg of the PWM controller to turn off the power supply.
Instead of an operational amplifier, transistors can be installed on the power supply board, which in principle perform the same function.
Next comes the rectifier part, which consists of various output voltages, 12 volts, +5 volts, -5 volts, +3.3 volts, of which for our purposes only a +12 volt rectifier will be needed (yellow output wires).
The remaining rectifiers and accompanying parts will need to be removed, except for the “duty” rectifier, which we will need to power the PWM controller and cooler.
The duty rectifier provides two voltages. Typically this is 5 volts and the second voltage can be around 10-20 volts (usually around 12).
We will use a second rectifier to power the PWM. A fan (cooler) is also connected to it.
If this output voltage is significantly higher than 12 volts, then the fan will need to be connected to this source through an additional resistor, as will be later in the circuits under consideration.
In the diagram below, I marked the high-voltage part with a green line, the “standby” rectifiers with a blue line, and everything else that needs to be removed with red.
So, we unsolder everything that is marked in red, and in our 12 volt rectifier we change the standard electrolytes (16 volts) to higher voltage ones, which will correspond to the future output voltage of our power supply. It will also be necessary to unsolder the 12th leg of the PWM controller and the middle part of the winding of the matching transformer - resistor R25 and diode D73 (if they are in the circuit) in the circuit, and instead of them solder a jumper into the board, which is drawn with a blue line in the diagram (you can simply close diode and resistor without soldering them). In some circuits this circuit may not exist.
Next, in the PWM harness on its first leg, we leave only one resistor, which goes to the +12 volt rectifier.
On the second and third legs of the PWM, we leave only the Master RC chain (in the diagram R48 C28).
On the fourth leg of the PWM we leave only one resistor (in the diagram it is designated as R49. Yes, in many other circuits between the 4th leg and the 13-14 legs of the PWM there is usually an electrolytic capacitor, we don’t touch it (if any) either, since it is designed for a soft start of the power supply. My board simply didn’t have it, so I installed it.
Its capacity in standard circuits is 1-10 μF.
Then we free the 13-14 legs from all connections, except for the connection with the capacitor, and also free the 15th and 16th legs of the PWM.
After all the operations performed, we should get the following.
This is what it looks like on my board (in the picture below).
Here I rewound the group stabilization choke with a 1.3-1.6 mm wire in one layer on the original core. It fit somewhere around 20 turns, but you don’t have to do this and leave the one that was there. Everything works well with him too.
I also installed another load resistor on the board, which consists of two 1.2 kOhm 3W resistors connected in parallel, the total resistance was 560 Ohms.
The native load resistor is designed for 12 volts of output voltage and has a resistance of 270 Ohms. My output voltage will be about 40 volts, so I installed such a resistor.
It must be calculated (at the maximum output voltage of the power supply at idle) for a load current of 50-60 mA. Since operating the power supply completely without load is not desirable, that’s why it is placed in the circuit.
View of the board from the parts side.
Now what will we need to add to the prepared board of our power supply in order to turn it into an regulated power supply;
First of all, in order not to burn the power transistors, we will need to solve the problem of load current stabilization and short circuit protection.
On forums for remaking similar units, I came across such an interesting thing - when experimenting with the current stabilization mode, on the forum pro-radio, forum member DWD I cited the following quote, I will quote it in full:
“I once told you that I couldn’t get the UPS to operate normally in current source mode with a low reference voltage at one of the inputs of the error amplifier of the PWM controller.
More than 50mV is normal, but less is not. In principle, 50mV is a guaranteed result, but in principle, you can get 25mV if you try. Anything less didn’t work. It does not work stably and is excited or confused by interference. This is when the signal voltage from the current sensor is positive.
But in the datasheet on the TL494 there is an option when negative voltage is removed from the current sensor.
I converted the circuit to this option and got an excellent result.
Here is a fragment of the diagram.
Actually, everything is standard, except for two points.
Firstly, is the best stability when stabilizing the load current with a negative signal from the current sensor an accident or a pattern?
The circuit works great with a reference voltage of 5mV!
With a positive signal from the current sensor, stable operation is obtained only at higher reference voltages (at least 25 mV).
With resistor values of 10 Ohm and 10 KOhm, the current stabilized at 1.5 A up to the output short circuit.
I need more current, so I installed a 30 Ohm resistor. Stabilization was achieved at a level of 12...13A at a reference voltage of 15mV.
Secondly (and most interestingly), I don’t have a current sensor as such...
Its role is played by a fragment of a track on the board 3 cm long and 1 cm wide. The track is covered with a thin layer of solder.
If you use this track at a length of 2cm as a sensor, then the current will stabilize at the level of 12-13A, and if at a length of 2.5cm, then at the level of 10A."
Since this result turned out to be better than the standard one, we will go the same way.
First, you will need to unsolder the middle terminal of the secondary winding of the transformer (flexible braid) from the negative wire, or better without soldering it (if the signet allows) - cut the printed track on the board that connects it to the negative wire.
Next, you will need to solder a current sensor (shunt) between the track cut, which will connect the middle terminal of the winding to the negative wire.
It is best to take shunts from faulty (if you find them) pointer ampere-voltmeters (tseshek), or from Chinese pointer or digital instruments. They look something like this. A piece 1.5-2.0 cm long will be sufficient.
You can, of course, try to do as I wrote above. DWD, that is, if the path from the braid to the common wire is long enough, then try to use it as a current sensor, but I didn’t do this, I came across a board of a different design, like this one, where the two wire jumpers that connected the output are indicated by a red arrow braids with a common wire, and printed tracks ran between them.
Therefore, after removing unnecessary parts from the board, I removed these jumpers and in their place soldered a current sensor from a faulty Chinese "tseshka".
Then I soldered the rewound inductor in place, installed the electrolyte and load resistor.
This is what my piece of board looks like, where I marked with a red arrow the installed current sensor (shunt) in place of the jumper wire.
Then you need to connect this shunt to the PWM using a separate wire. From the side of the braid - with the 15th PWM leg through a 10 Ohm resistor, and connect the 16th PWM leg to the common wire.
Using a 10 Ohm resistor, you can select the maximum output current of our power supply. On the diagram DWD The resistor is 30 ohms, but start with 10 ohms for now. Increasing the value of this resistor increases the maximum output current of the power supply.
As I said earlier, the output voltage of my power supply is about 40 volts. To do this, I rewound the transformer, but in principle you can not rewind it, but increase the output voltage in another way, but for me this method turned out to be more convenient.
I’ll tell you about all this a little later, but for now let’s continue and start installing the necessary additional parts on the board so that we have a working power supply or charger.
Let me remind you once again that if you did not have a capacitor on the board between the 4th and 13-14 legs of the PWM (as in my case), then it is advisable to add it to the circuit.
You will also need to install two variable resistors (3.3-47 kOhm) to adjust the output voltage (V) and current (I) and connect them to the circuit below. It is advisable to make the connection wires as short as possible.
Below I have given only part of the diagram that we need - such a diagram will be easier to understand.
In the diagram, newly installed parts are indicated in green.
Diagram of newly installed parts.
Let me give you a little explanation of the diagram;
- The topmost rectifier is the duty room.
- The values of the variable resistors are shown as 3.3 and 10 kOhm - the values are as found.
- The value of resistor R1 is indicated as 270 Ohms - it is selected according to the required current limitation. Start small and you may end up with a completely different value, for example 27 Ohms;
- I did not mark capacitor C3 as a newly installed part in the expectation that it might be present on the board;
- The orange line indicates elements that may have to be selected or added to the circuit during the process of setting up the power supply.
Next we deal with the remaining 12-volt rectifier.
Let's check what maximum voltage our power supply can produce.
To do this, we temporarily unsolder from the first leg of the PWM - a resistor that goes to the output of the rectifier (according to the diagram above at 24 kOhm), then you need to turn on the unit to the network, first connect it to the break of any network wire, and use a regular 75-95 incandescent lamp as a fuse Tue In this case, the power supply will give us the maximum voltage it is capable of.
Before connecting the power supply to the network, make sure that the electrolytic capacitors in the output rectifier are replaced with higher voltage ones!
All further switching on of the power supply should be carried out only with an incandescent lamp; it will protect the power supply from emergency situations in case of any errors. In this case, the lamp will simply light up, and the power transistors will remain intact.
Next we need to fix (limit) the maximum output voltage of our power supply.
To do this, we temporarily change the 24 kOhm resistor (according to the diagram above) from the first leg of the PWM to a tuning resistor, for example 100 kOhm, and set it to the maximum voltage we need. It is advisable to set it so that it is 10-15 percent less than the maximum voltage that our power supply is capable of delivering. Then solder a permanent resistor in place of the tuning resistor.
If you plan to use this power supply as a charger, then the standard diode assembly used in this rectifier can be left, since its reverse voltage is 40 volts and it is quite suitable for a charger.
Then the maximum output voltage of the future charger will need to be limited in the manner described above, around 15-16 volts. For a 12-volt battery charger, this is quite enough and there is no need to increase this threshold.
If you plan to use your converted power supply as an regulated power supply, where the output voltage will be more than 20 volts, then this assembly will no longer be suitable. It will need to be replaced with a higher voltage one with the appropriate load current.
I installed two assemblies on my board in parallel, 16 amperes and 200 volts each.
When designing a rectifier using such assemblies, the maximum output voltage of the future power supply can be from 16 to 30-32 volts. It all depends on the model of the power supply.
If, when checking the power supply for the maximum output voltage, the power supply produces a voltage less than planned, and someone needs more output voltage (40-50 volts for example), then instead of the diode assembly, you will need to assemble a diode bridge, unsolder the braid from its place and leave it hanging in the air, and connect the negative terminal of the diode bridge in place of the soldered braid.
Rectifier circuit with diode bridge.
With a diode bridge, the output voltage of the power supply will be twice as high.
Diodes KD213 (with any letter) are very suitable for a diode bridge, the output current with which can reach up to 10 amperes, KD2999A,B (up to 20 amperes) and KD2997A,B (up to 30 amperes). The last ones are best, of course.
They all look like this;
In this case, it will be necessary to think about attaching the diodes to the radiator and isolating them from each other.
But I took a different route - I simply rewound the transformer and did it as I said above. two diode assemblies in parallel, since there was space for this on the board. For me this path turned out to be easier.
Rewinding a transformer is not particularly difficult, and we’ll look at how to do it below.
First, we unsolder the transformer from the board and look at the board to see which pins the 12-volt windings are soldered to.
There are mainly two types. Just like in the photo.
Next you will need to disassemble the transformer. Of course, it will be easier to deal with smaller ones, but larger ones can also be dealt with.
To do this, you need to clean the core from visible varnish (glue) residues, take a small container, pour water into it, put the transformer there, put it on the stove, bring to a boil and “cook” our transformer for 20-30 minutes.
For smaller transformers this is quite enough (less is possible) and such a procedure will not harm the core and windings of the transformer at all.
Then, holding the transformer core with tweezers (you can do it right in the container), using a sharp knife we try to disconnect the ferrite jumper from the W-shaped core.
This is done quite easily, since the varnish softens from this procedure.
Then, just as carefully, we try to free the frame from the W-shaped core. This is also quite easy to do.
Then we wind up the windings. First comes half of the primary winding, mostly about 20 turns. We wind it up and remember the direction of winding. The second end of this winding does not need to be unsoldered from the point of its connection with the other half of the primary, if this does not interfere with further work with the transformer.
Then we wind up all the secondary ones. Usually there are 4 turns of both halves of 12-volt windings at once, then 3+3 turns of 5-volt windings. We wind everything up, unsolder it from the terminals and wind a new winding.
The new winding will contain 10+10 turns. We wind it with a wire with a diameter of 1.2 - 1.5 mm, or a set of thinner wires (easier to wind) of the appropriate cross-section.
We solder the beginning of the winding to one of the terminals to which the 12-volt winding was soldered, we wind 10 turns, the direction of winding does not matter, we bring the tap to the “braid” and in the same direction as we started - we wind another 10 turns and the end solder to the remaining pin.
Next, we isolate the secondary and wind the second half of the primary onto it, which we wound earlier, in the same direction as it was wound earlier.
We assemble the transformer, solder it into the board and check the operation of the power supply.
If during the process of adjusting the voltage any extraneous noise, squeaks, or crackles occur, then to get rid of them, you will need to select the RC chain circled in the orange ellipse below in the figure.
In some cases, you can completely remove the resistor and select a capacitor, but in others you can’t do it without a resistor. You can try adding a capacitor, or the same RC circuit, between 3 and 15 PWM legs.
If this does not help, then you need to install additional capacitors (circled in orange), their ratings are approximately 0.01 uF. If this doesn’t help much, then install an additional 4.7 kOhm resistor from the second leg of the PWM to the middle terminal of the voltage regulator (not shown in the diagram).
Then you will need to load the power supply output, for example, with a 60-watt car lamp, and try to regulate the current with resistor “I”.
If the current adjustment limit is small, then you need to increase the value of the resistor that comes from the shunt (10 Ohms) and try to regulate the current again.
You should not install a tuning resistor instead of this one; change its value only by installing another resistor with a higher or lower value.
It may happen that when the current increases, the incandescent lamp in the network wire circuit will light up. Then you need to reduce the current, turn off the power supply and return the resistor value to the previous value.
Also, for voltage and current regulators, it is best to try to purchase SP5-35 regulators, which come with wire and rigid leads.
This is an analogue of multi-turn resistors (only one and a half turns), the axis of which is combined with a smooth and coarse regulator. At first it is regulated “Smoothly”, then when it reaches the limit, it begins to be regulated “Roughly”.
Adjustment with such resistors is very convenient, fast and accurate, much better than with a multi-turn. But if you can’t get them, then buy ordinary multi-turn ones, such as;
Well, it seems like I told you everything that I planned to complete on remaking the computer power supply, and I hope that everything is clear and intelligible.
If anyone has any questions about the design of the power supply, ask them on the forum.
Good luck with your design!
Many people assemble various radio-electronic structures, and their use sometimes requires a powerful power source. Today I’ll tell you how with an output power of 250 watts, and the ability to adjust the voltage from 8 to 16 volts at the output, from an ATX unit model FA-5-2.
The advantage of this power supply is output power protection (that is, against short circuit) and voltage protection.
2. We unsolder from the circuit the parts that are in the +3.3v, -5v, -12v circuits (we don’t touch +5 volts yet). What to remove is shown in red, and what to redo is shown in blue in the diagram:
4. We provide power and voltage protection. Add two trim resistors:
Setting up the voltage protection is done as follows: we twist the resistor R4 to the side where the ground is connected, set R3 to maximum (higher resistance), then by rotating R2 we achieve the voltage we need - 16 volts, but set it 0.2 volts more - 16.2 volts, slowly turn R4 before the protection is triggered, turn off the block, slightly reduce the resistance R2, turn on the block and increase the resistance R2 until the output reaches 16 volts. If during the last operation the protection was triggered, then you went overboard with the R4 turn and will have to repeat everything again. After setting up the protection, the laboratory unit is completely ready for use.
How to make a full-fledged power supply yourself with an adjustable voltage range of 2.5-24 volts is very simple; anyone can repeat it without any amateur radio experience.
We will make it from an old computer power supply, TX or ATX, it makes no difference, fortunately, over the years of the PC Era, every home has already accumulated a sufficient amount of old computer hardware and there is probably a power supply there too, so the cost homemade products will be insignificant, and for some masters it will be equal to zero rubles.
I got this AT block for modification.
Look what is written on the case.
There are many options for modifying a standard computer power supply, but they are all based on a change in the wiring of the IC chip - TL494CN (its analogues DBL494, KA7500, IR3M02, A494, MV3759, M1114EU, MPC494C, etc.).
Let's look at several options execution of computer power supply circuits, perhaps one of them will be yours and dealing with the wiring will become much easier.
Scheme No. 1.
Let's get to work.
First you need to disassemble the power supply housing, unscrew the four bolts, remove the cover and look inside.
In my case, a KA7500 chip was found on the board, which means we can begin to study the wiring and the location of unnecessary parts that need to be removed.
Let's disconnect the power and fan, solder or cut out the output wires so that they don't interfere with our understanding of the circuit, leave only the necessary ones, one yellow (+12v), black (common) and green* (start ON) if there is one.
This is done because our modified unit will produce not +12 volts, but up to +24 volts, and without replacement, the capacitors will simply explode during the first test at 24v, after a few minutes of operation. When selecting a new electrolyte, it is not advisable to reduce the capacity; increasing it is always recommended.
The most important part of the job.
We will remove all unnecessary parts in the IC494 harness and solder other nominal parts so that the result is a harness like this (Fig. No. 1).
We will only need these legs of the microcircuit No. 1, 2, 3, 4, 15 and 16, do not pay attention to the rest.
Explanation of symbols.
Some resistors that are already soldered into the wiring diagram can be suitable without replacing them, for example, we need to put a resistor at R=2.7k connected to the “common”, but there is already R=3k connected to the “common”, this suits us quite well and we leave it there unchanged (example in Fig. No. 2, green resistors do not change).
Thus, we review and redo all the circuits on the six legs of the microcircuit.
This was the most difficult point in the rework.
We make voltage and current regulators.
Voltage and current control.
To control we need a voltmeter (0-30v) and an ammeter (0-6A).
IMPORTANT- inside the device there is a Current resistor (Current sensor), which we need according to the diagram (Fig. No. 1), therefore, if you use an ammeter, then you do not need to install an additional Current resistor; you need to install it without an ammeter. Usually a homemade RC is made, a wire D = 0.5-0.6 mm is wound around a 2-watt MLT resistance, turn to turn for the entire length, solder the ends to the resistance terminals, that's all.
Everyone will make the body of the device for themselves.
You can leave it completely metal by cutting holes for regulators and control devices. I used laminate scraps, they are easier to drill and cut.
