Very often you have to look under the power supply cover: inspect its components, measure voltages, and sometimes resolder components.

Computer power supplies, being high-voltage power devices, fail much more often than other computer components. Regardless of manufacturer and price, device and principle of operation of the ATX power supply unchangeable. Schematically, the design of a computer power supply can be divided into:

Input circuit (1)
Mains rectifier (2)
Self-generating power supply (3)
Power stage (4)
Secondary rectifiers (5)

IN internal ATX power supply device

The input circuit consists of a network filter that suppresses interference in the network from the operation of the power supply. The network rectifier of the computer power supply includes a diode assembly (bridge) and rectifier capacitors. The self-oscillating power supply works when the computer is turned off (not from the network, of course, but with the Power button), it supplies a standby supply voltage of +5VStb to the motherboard controllers. A voltage of +310V is supplied to the power stage from the rectifier. The transistors of the power stage of the ATX power supply operate in a push-pull circuit together with a power transformer and are controlled by a PWM chip. From the secondary windings of the power transformer, voltage is supplied to secondary low-voltage rectifiers. The PWM chip is triggered by a signal from the motherboard “Power On”, triggering, accordingly, the transistor-transformer converter and applying voltage to its secondary windings. In the secondary windings of the computer power supply, in addition to diode assemblies (on radiators), chokes are used.

Block diagram of a computer power supply

Computer power supply is a pulse device. Unlike linear ones, switching power supplies are more compact and have high efficiency and lower heat losses. The 220V mains voltage is supplied through a surge filter to a rectifier consisting of diodes and two series-connected electrolytic capacitors. The self-generating power supply is also powered, generating a standby voltage of +5v stb. From the rectifier, a voltage of 310V is supplied to a power stage implemented using powerful transistor switches and a transformer. The power stage is controlled by pulses coming from a PWM (Pulse Width Modulation) generator microcircuit through a matching transformer to the key bases. The generated pulse voltage is removed from the secondary windings of the power transformer and rectified by diodes and capacitors. The output voltage is controlled by a special protection circuit that generates a Power-Ok (Power-Good) signal. If the output voltages deviate from the nominal values, the Power-Ok signal is not supplied to the motherboard controller, thereby blocking the computer from starting.

Schematic diagrams of ATX power supplies

ATX power supply output voltages

Pinout of ATX power supply connectors

Repair of computer power supplies

Repair of computer power supplies You should start by checking the supply of ~220V mains voltage to the rectifier. Next, you need to check the presence of +310V at the output of the rectifier (do not forget that the capacitors of the rectifier of the computer power supply are connected in series and the voltage at their terminals will be approximately 150-160V). Make sure there is voltage +5v stb and Power-Ok (pink and green wires). If they are missing, you should check the standby power supply and the PWM chip (if there is no Power-Ok voltage). If the generation of standby voltage +5v stb and Power-Ok is normal, focus your attention on the power switches and the secondary rectifier of the power supply. Do not forget that to test semiconductors and capacitors, it is better to remove them from the circuit.

ATX POWER SUPPLY, CIRCUIT

Computer power supplies are becoming more and more popular among radio amateurs every day.ATX. At a relatively low price, they represent a powerful, compact voltage source of 5 and 12 V 250 - 500 watts. BPATXcan be used in chargers for car batteries, and in laboratory power supplies, and in welding inverters, and many more applications can be found for them with a certain imagination. Moreover, if the power supply circuitATXand is subject to alteration, then minimal.

The circuit design of these power supplies is approximately the same for almost all manufacturers. A small difference applies only to AT and ATX power supplies. The main difference between them is that the AT power supply does not support the advanced power management standard in software. You can turn off this power supply only by stopping the supply of voltage to its input, and in ATX power supplies it is possible to programmatically turn it off using a control signal from the motherboard. As a rule, an ATX board is larger than an AT board and is elongated vertically.

In any computer power supply, the +12 V voltage is intended to power the disk drive motors. The power supply for this circuit must provide a large output current, especially in computers with many drive bays. This voltage is also supplied to the fans. They consume current up to 0.3 A, but in new computers this value is below 0.1 A. +5 volt power is supplied to all components of the computer, therefore it has very high power and current, up to 20 A, and the +3.3 volt voltage is intended exclusively for powering the processor. Knowing that modern multi-core processors have a power of up to 150 watts, it is not difficult to calculate the current of this circuit: 100 watts/3.3 volts = 30 A! Negative voltages -5 and -12 V are ten times weaker than the main positive ones, so there are simple 2-amp diodes without radiators.

The tasks of the power supply also include suspending the functioning of the system until the input voltage reaches a value sufficient for normal operation. Each power supply undergoes internal checks and output voltage testing before being allowed to start the system. After this, a special Power Good signal is sent to the motherboard. If this signal is not received, the computer will not work.

The Power Good signal can be used for manual reset if applied to the clock generator chip. When the Power Good signal circuit is grounded, clock generation stops and the processor stops. After opening the switch, a short-term processor initialization signal is generated and normal signal flow is allowed - a hardware reboot of the computer is performed. In computer power supplies of the ATX type, there is a signal called PS ON; it can be used by the program to turn off the power source.

Here you can download computer power supplies, and here is a very useful description, types and principle of operation of AT and ATX power supplies.To check the functionality of the power supply, you should load the power supply with lamps for car headlights and measure all output voltages with a tester. If the voltage is within normal limits. It is also worth checking the change in the voltage supplied by the power supply with a change in load.

The operation of these power supplies is very stable and reliable, but in the event of combustion, powerful transistors, low-resistance resistors, rectifier diodes on the radiator, varistors, transformer and fuse most often fail.

Quite often, when repairing or converting an ATX computer power supply into a charger or laboratory source, a diagram of this unit is required. Considering that there are a great many models from such sources, we decided to collect a collection of this topic in one place.

In it you will find typical power supply circuits for computers, both modern ATX type and already noticeably outdated ATX. It is clear that newer and more relevant options appear every day, so we will try to quickly replenish the collection of schemes with newer options. By the way, you can help us with this.

Collection of circuit diagrams for ATX and AT power supplies

ATX 310T, ATX-300P4-PFC, ATX-P6; Octek X25D AP-3-1 250W; Sunny ATX-230;
BESTEC ATX-300-12ES on UC3842, 3510 and A6351 chips; BESTEC ATX-400W(PFC) on ICE1PCS01, UC3842, 6848, 3510, LM358 chips
Chieftec computer power supply diagram CFT-500A-12S, CFT-560A-12S, CFT-620A-12S (CM6800G, PS222S, SG6858 or SG6848) APS-1000C, TNY278PN, CM6800TX; Chieftec 850W CFT-850G-DF; 350W GPS-350EB-101A; 350W GPS-350FB-101A; 500W GPS-500AB-A; 550W GPS-550AB-A; 650W GPS-650AB-A and Chieftec 650W CFT-650A-12B; 1000W CFT-1000G-DF and Chieftec 1200W CFT-1200G-DF; CFT-600-14CS, CFT-650-14CS, CFT-700-14CS, CFT-750-14CS on LD7550B

Chip Goal 250W, (with CG8010DX)
Codegen QORI 200xa at 350W on the SG6105 chip
Colors-It computer block diagram 300W 300U-FNM (sg6105 and sg6848); 330W - 330U PWM SG6105 duty station on TDA865; 330U IW-P300A2-0 R1.2 sg6105; 330U PWM SG6105 and duty station M605; 340W - 340U PWM SG6105; 350U-SCE- KA339, M605, 3842; 350-FCH PWM 3842, LM339 and M605; 340U SG6105 and 5H0165R; 400U SG6105 and 5H0165R; 400PT, 400U SCH 3842, LM339 and M605; 500T SG6105 and 5H0165R; 600PT(ATX12V-13), WT7525, 3B0365
ComStars 400W KT-400EX-12A1 on UC3543A circuit
CWT PUH400W
Delta Electronics circuit diagram of a computer power supply DPS-210EP, DPS-260-2A 260W on microassemblies NE556, PQ05RF11, ML4824-1, LM358, LM339D, PQ30R21; DPS-470 AB A 500W, APFC and PWM DNA1005A or DNA1005;
DELUX ATX-350W P4 on AZ7500BP and LP7510 circuit
FSP Epsilon 600W FX600-GLN duty circuit, assembled on the FSDM0265R IC; FSP145-60SP KA3511, duty room KA1N0165R; FSP250-50PLA, APFC on CM6800, field effect transistors STP12NM50, TOP243Y, control PS223; FSP ATX-350PNR DM311 and main PWM FSP3528; FSP ATX-300PAF and ATX-350 on DA311; 350W FSP350-60THA-P And 460W FX500-A FSP3529Z (similar to SG6105; ATX-400 400W, DM311; ATX-400PNF,; OPS550-80GLN, APFC on field-effect transistors 20N60C3, duty on DM311; OPS550-80GLN, APFC+PWM control module on CM6800G; Epsilon 600W FX600-GLN(scheme); ATX-300GTF on field truck 02N60
Green Tech circuit diagram of a 300W computer power supply model MAV-300W-P4 on a TL494CN and WT7510 chip
Hiper HPU-4S425-PU 425W APFC, based on CM6805, VIPer22A, LM393, PS229 chips
iMAC G5 A1058, APFC on 4863G, duty station on TOP245YN, main power supply on 3845B
J.N.C. 250W lc-b250 atx
Krauler ATX-450 450W (m.s. TL3845, LD7660, WT7510)
LWT 2005 on LM339N chip
M-Tech 450W KOB-AP4450XA microassembly SG6105Z
Maxpower PX-300W chip SG6105D
Microlab circuit diagram of a computer power supply 420W, on WT7510, PWM TL3842 duty station - 5H0165R; M-ATX-420W based on UC3842, supervisor 3510 and LM393
PowerLink 300W LPJ2-18 on LPG-899 microassembly
Powerman IP-P550DJ2-0, 350W IP-P350AJ, 350W IP-P350AJ2-0 ver.2.2 on supervisor W7510, 450W IP-S450T7-0, 450W IP-S450T7-0 rev:1.3 (3845, WT7510 and A6259H)
Power Master 230W model LP-8, 250W FA-5-2, 250W AP-3-1, PM30006-02 ATX 300W
Power Mini P4,Model PM-300W. Main micro assembly SG6105
Both 230 and 250 watt power supplies are based on the very popular TL494 chip. The video repair instructions tell you how to troubleshoot and safety precautions when repairing any switching power supplies, which includes computer ones.

SevenTeam ST-200HRK (IC: LM339, UTC51494, UC3843AN)
ShenShon circuit diagram of a computer power supply 400W model SZ-400L and 450W model SZ450L, duty station on C3150, AT2005; 350w on AT2005, aka WT7520, or LPG899
Sparkman SM-400W on KA3842A, WT7510 circuit
SPS: SPS-1804-2(M1) and SPS-1804E

Personal computer power supply - used to supply power to all components and components of the system unit. A standard ATX power supply must provide the following voltages: +5, -5 V; +12, -12 V; +3.3 V; Almost any standard power supply has a powerful fan located at the bottom. On the rear panel there is a socket for connecting a network cable and a button to turn off the power supply, but on cheap Chinese versions it may not be available. From the opposite side comes a huge pile of wires with connectors for connecting the motherboard and all other components of the system unit. Installing the power supply into the case is usually quite simple. Installing a computer power supply into the system unit case To do this, insert it into the upper part of the system unit, and then secure it with three or four screws to the rear panel of the system unit. There are designs of the system unit case in which the power supply is placed in the lower part. In general, if anything, I hope you can get your bearings

Cases of breakdowns of computer power supplies are not uncommon. The causes of malfunctions can be: Voltage surges in the AC network; Poor workmanship, especially for cheap Chinese power supplies; Unsuccessful circuit design solutions; Use of low-quality components in manufacturing; Overheating of radio components due to contamination of the power supply or fan stoppage.

Most often, when a computer power supply breaks down, there are no signs of life in the system unit, the LED indication does not light up, there are no sound signals, and the fans do not spin. In other cases of malfunction, the motherboard does not start. At the same time, the fans are spinning, the indicator lights up, the drives and hard drive show signs of life, but there is nothing on the monitor display, only a dark screen.

Problems and defects can be completely different - from complete inoperability to permanent or temporary failures. As soon as you begin the repair, make sure that all contacts and radio components are visually in order, the power cords are not damaged, the fuse and switch are working, and there are no short circuits to ground. Of course, the power supplies of modern equipment, although they have common principles of operation, are quite different in their circuitry. Try to find a diagram on a computer source, this will speed up the repair.

The heart of any computer power supply circuit, ATX format, is a half-bridge converter. Its operation and operating principle are based on the use of push-pull mode. Stabilization of the device's output parameters is carried out using control signals.

Pulse sources often use the well-known TL494 PWM controller chip, which has a number of positive characteristics:

ease of use in electronic designs
good operating technical parameters, such as low starting current and, most importantly, speed
availability of universal internal protective components

The operating principle of a typical computer power supply can be seen in the block diagram below:

The voltage converter converts this value from variable to constant. It is made in the form of a diode bridge that converts voltage and a capacitance that smoothes out oscillations. In addition to these components, additional elements may be present: thermistors and a filter. The pulse generator generates pulses at a given frequency, which power the transformer winding. HE performs the main work in a computer power supply, this is the conversion of current to the required values and galvanic isolation of the circuit. Next, the alternating voltage from the windings of the transformer goes to another converter, consisting of semiconductor diodes that equalize the voltage and a filter. The latter cuts off ripple and consists of a group of inductors and capacitors.

Since many parameters of such a power supply “float” at the output due to unstable voltage and temperature. But if you carry out operational control of these parameters, for example, using a controller with a stabilizer function, then the block diagram shown above will be quite suitable for use in computer technology. Such a simplified power supply circuit using a pulse width modulation controller is shown in the following figure.

PWM controller, for example UC3843, in this case it regulates the amplitude of changes in the signals following through a low-pass filter, watch the video lesson just below:

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.

- Directory in .chm format. The author of this file is Pavel Andreevich Kucheryavenko. Most of the source documents were taken from the website pinouts.ru - brief descriptions and pinouts of more than 1000 connectors, cables, adapters. Descriptions of buses, slots, interfaces. Not only computer equipment, but also cell phones, GPS receivers, audio, photo and video equipment, game consoles, car interfaces.

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.

Wiring for ATX power supply connectors (ATX12V) with ratings and color coding of wires:

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