SONY PLAYSTATION, or 32-bit video set-top box circuitry features. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Телевидение

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For video game lovers, a wide range of video game consoles (VVP) is being produced today: from "Dendy" to "Nintendo Ultra-64". Continuing a series of articles about the circuitry of such devices, the author talks about the "Sony PlayStation" - a Japanese 32-bit IVP that conquered the entire gaming world. The information presented will not only facilitate its competent operation and self-repair, but also expand the technical horizons of readers.

Despite the short history of the development of 32-bit IVP, it has already been marked by the competitive struggle of transnational corporations producing computer equipment. Comparative characteristics of the most famous set-top boxes of this class are given in Table. 1. They can be conditionally divided into "exotic" and "standard" The former include less common or narrow-profile IVP: "Sega32X" - the original "prefix to the prefix", expanding the capabilities of the 16-bit "Sega Mega Drive-2"; "Philips CD-i" - a multifunctional TV set-top box for playing information from interactive optical discs in CD-i format; "Commodore CD32" or "CDTV" - a project ahead of its time, contributed to the beginning of the distribution of game programs on CD-ROM, but the developer did not have the persistence and funds to conquer the market.

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"Standard" 32-bit IVP can be considered "3DO" [1], "Sega Saturn", "Sony PlayStation" and their numerous clones. General characteristics of these products: game programs are stored on laser compact discs (CD), television image is formed in NTSC or PAL standards with stereo sound, a variety of peripheral devices are provided (from a "laser" gun to a car steering wheel with pedals), it is possible to listen to ordinary music CD, work with Photo-CD and Video-CD formats. The prefix "3DO", having rather modest technical characteristics, is a success, as it appeared on the market a little earlier than its competitors. IVP "Sega Saturn" is prevented from becoming popular by unsuccessful pricing and insufficient software support. Nevertheless, for some time it was considered the main competitor of the "Sony PlayStation" (hereinafter we will simply call it "PlayStation"), which is considered by many to be the best of the 32-bit IVPs. This is confirmed by a large number (more than 600 are known) of game programs for it, created by such well-known companies as Electronic Arts, Mindscape, Capcom, Konami, Lucas Arts, Disney Software. High-speed XNUMXD games with a "live" image and a virtual view camera are close in level to those implemented on computers with a Pentium processor of younger models.

The first "PlayStation" models designed for Japanese, American or European TV standards were not fully compatible. Later ones became universal and work with CDs of both branded and South Asian production. Circuitry and constructive-technological design of "PlayStation" are thought out very carefully. The relatively high price pays off with increased quality and reliability.

HOW PLAYSTATION IS WORKED

Next, we will talk about one of the latest models of "PlayStation" - SCPH5502. Considering its device, we will, if possible, use the reference designations of the elements marked on printed circuit boards, although they do not always correspond to our standards (for example, transistors are denoted by the letter Q, not VT, microcircuits - IC, not DD or DA, connectors are CN, not X). The branded numbering of the elements is three-digit, and the digit in the most significant digit indicates belonging to a certain subsystem of the set-top box. Unfortunately, many items are not marked. If their designations were still found from other sources, they are given with an apostrophe on the diagrams and in the text (for example, IC105'). The rest are designated according to ESKD with one-two-digit serial numbering within each of the diagrams. For convenience, the types of most transistors and diodes are indicated according to the Siemens catalog [2]. In reality, the "PlayStation" in many cases has elements of Asian production, the type of which cannot be determined due to the lack of marking.

The standard delivery set of "PlayStation" includes a system unit (console), a joystick, a power cord, a cable for connecting to a TV set, and a demo CD. The connection diagram of the system unit is shown in fig. 1. Its heart is the processor board, on which there are almost all the main nodes of the set-top box and seven connectors:

• CN102 - socket for connection with the switching board;
• CN103, CN104 - plugs for parallel and serial ports, respectively;
• CN502 - TV plug (low frequency);
• CN602 - plug for connecting to the power board;
• CN701, CN702 - plug and socket for connecting the power and information circuits of the CDROM drive, respectively.

Said drive contains electromechanical units of CD rotation systems and reading head movement with infrared semiconductor laser and receiving photomatrix. Pressing the "OPEN" button opens access to the disk container for its installation or removal.

The breakout board distributes the circuits of connector CN102 of the processor board to four outlets. Two of them (nine-pin) are designed to connect the main ("1") and additional ("2") joysticks to the console, and the rest (eight-pin) - for other peripherals.

The IVP is powered from the 220 V mains through a pulse voltage converter located on the power board. The purpose of the "POWER" and "RESET" buttons is standard: turning on the power and setting the processor system to its initial state, respectively. The converter works all the time while the mains plug is inserted into the socket. At idle, power consumption does not exceed 2,3 watts. After turning on the set-top box with the "POWER" button, it increases to 6 ... 11 watts.

Board-to-board connections of power circuits are made with ordinary wires, and high-frequency (information) ones - with an elastic ribbon cable. In the manufacture of attachments, modern technology of automated mounting of elements on the surface of printed circuit boards is widely used. Almost all elements installed on the processor board are the so-called SMD (Surface Mounting Device). In this design, today not only resistors, capacitors, transistors and microcircuits are produced, but also inductors, fuse links, connectors and much more.

POWER BOARD

Unlike 8- and 16-bit IVPs, which have linear power supplies, the "PlayStation" uses a pulsed one. Its advantages are efficiency, low heat generation, high stability of output voltages during mains fluctuations and changes in load currents. In various operating modes, the set-top box consumes a current of 180 ... 800 mA from the source along the +7,6 V circuit and 360 ... 500 mA along the +3,3 V circuit. Output voltage ripples with the load off do not exceed 100 mV. Source efficiency - 53...75%. Good parameters are achieved due to the increased conversion frequency and the use of a quasi-resonant circuit [3, 4].

The schematic diagram of the power board is shown in fig. 2. Through the noise suppression filter C001L001C002, the mains voltage is supplied to the rectifier - diode bridge D001 - D004 and then to the voltage converter. Capacitor C003 smooths out ripples. Capacitors C010, C011, connected in series to increase reliability, connect the rectifier to the common wire (GND circuit) of the set-top box, which weakens the influence of interference penetrating through the network. According to the electrical safety rules, the total capacitance of these capacitors should not exceed 6600 pF [5].

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A single-cycle voltage converter is assembled according to the blocking oscillator circuit with reverse diode switching. Its work is based on the accumulation of energy in the magnetic field of the transformer T001 during the open state of the key and its subsequent transfer to the load. The "self-protected" key on transistors Q001 and Q002 is designed in such a way that during overloads and transients, the current flowing through it is limited without reaching dangerous values. The current sensor consists of a resistor R009 and a diode D008. The voltage from it is supplied to the base of transistor Q002, opening it with a sharp increase in the emitter current of transistor Q001. As a result, the base circuit of the latter is shunted, which leads to current limitation.

During the initial start-up, the key is opened by the current flowing through the resistor R003. The feedback voltage required for the operation of the generator is supplied to the base of transistor Q001 from winding II of transformer T001. Capacitor C004, together with the collector junction capacitance of transistor Q001 and the leakage inductance of transformer T001 form a series oscillating circuit tuned to a frequency close to the conversion frequency. As a result, the voltage on the collector Q001 acquires an almost sinusoidal shape [3, 4]. The snubber circuit C005R002D005 protects transistor Q001 from breakdown.

The voltages of the secondary windings III and IV of the transformer T001 are rectified by Schottky barrier diodes D101, D102, which are characterized by a small forward voltage drop, which improves the energy characteristics of the source. Resistors R101, R102 - ballast. They create the load necessary for stable operation of the converter at idle. Zener diode D103 with a stabilization voltage of 10 V limits the possible voltage surges during transients. After passing the smoothing filters C101L101C103 and C102L102C104, the rectified voltages are fed through the SW101 switch and the CN101 connector to the processor board.

After closing the contacts of the SW101 switch, in the presence of both supply voltages, the green LED PD101 lights up, which is included in the collector circuit of the "digital" transistor (digital transistor) Q101. This relatively new electronic device is logically NOT an open collector element. It consists of a conventional transistor and a resistive divider in the base circuit. The input of the latter can be connected directly to the output of a digital TTL or CMOS microcircuit. "Digital" transistors differ from one another in structure (npn or pnp) and resistor values ​​(1 ... 47 kOhm).

The output voltage of the converter is stabilized. A voltage proportional to the output in the +3,3 V circuit is fed to the input of the mismatch amplifier IC101 through a divider of resistors R106, R107. The output of the amplifier through resistors R103, R104 and the PC001 optocoupler LED is connected to the +7,6 V circuit. When any of the output voltages increases, the current through the LED increases, and vice versa. As a result, the resistance of the collector-emitter section of the phototransistor of the optocoupler, which is included in the feedback circuit of the blocking oscillator, changes.

This process causes such a change in the frequency and duration of the generated pulses that the output voltages return to the nominal values. For example, with an increase in load power by 1,5 times, the conversion frequency decreases from 160 to 120 kHz with a simultaneous increase in the relative duration of the open state of the transistor Q001 (i.e., energy accumulation time). Chains R010C008 and R105C105 give the automatic voltage regulation system dynamic stability. The stabilization coefficient is quite high: the voltage in the +3,3 V circuit changes by only 0,5% when the load current increases from 0,035 to 1 A. For a voltage of +7,6 V, this indicator is worse - 11% when the load current changes from 0,075 to 1 A. If any of the outputs is short-circuited, the converter switches to the current stabilization mode. After the short circuit is removed, normal operation is restored automatically.

As already mentioned, the converter works all the time while the mains plug is inserted into the socket, even if the contacts of the switch SW101 "POWER" are open. Therefore, you should not leave the IVP in this state for a long time - a malfunction of the power board can lead to a fire. Be aware of the high voltage on this board when opening the EVP for repairs.

The power board has an IC102 timer that generates a reset signal for the processor board. When the set-top box is turned on with the SW101 button, as well as when the SW102 button is pressed and released, a low logic level pulse with a duration of 500 ms appears at its output. The time-setting element is the capacitor C106. Circuit D105, R111, R112, D106 generates a reset signal in case of a short-term decrease in voltage in the +7,6 V circuit. As a result, after the so-called “drawdowns” of the mains voltage, the IVP processor automatically restarts. Stabilization voltage D105 - 5,1 V.

When choosing a replacement for the active elements of the power board, one should take into account their parameters given in Table. 2.

If necessary, the "digital" transistor Q101 can be replaced with any conventional low-power n-pn structure by connecting a resistor with a resistance of approximately 10 kΩ in series to its base circuit. As IC101, you can use TLP431CLP, TL1431 (Texas Instruments), HA174 (Hitachi), KR142EN19. In the latter case, it must be borne in mind that there are batches of devices with non-standard pinouts. The TLP621 optocoupler (PC001) can be replaced with a TLP521 or NEC256.

In order to increase the reliability of the power board and reduce interference to other electronic devices created by it at the time of connection to the network, it is recommended to include a resistor with a resistance of 001 ... 10 Ohm with a rated power of at least 100 W.

SWITCH BOARD

The circuit board diagram is shown in fig. 3, the location of the contacts of its external connectors - in fig. 4.

Please note that the circuits called OUT with different digital indices are input for the IVP, and SYN and PE are output. The board is shielded. A flexible cable 80 mm long connects it to the socket CN102 of the processor board. Please note that the order of the contacts of the XS3 socket is reversed with respect to the CN102.

 Joysticks, pistol, steering wheel, steering wheel and other "tools" of the game are connected to sockets XS1 and XS4. The XS2 and XS5 are intended for SCPH-1020 Memory Cards, business card-sized devices containing non-volatile FLASH memory that remembers the current states of interrupted games. This favorably distinguishes "PlayStation" from other TRPs, since by transferring the card to any console of the same type, you can continue the game. The capacity of the "Memory Card" is 1 Mbit (15 memory blocks of 64 Kb each, the sixteenth is used for service purposes). "Memory Card +" with a capacity of 8 Mbps (120 blocks) are issued.

JOYSTICK

Joysticks for "PlayStation" are convenient and reliable in operation. Note that, in addition to the standard ones, there are more advanced devices with force feedback (force feedback), in which, for example, vibration simulates the reaction of the game object (aircraft, car) to a control action. Known joysticks with wireless (infrared rays) connection with the processor unit, as well as precision analog-digital, allowing you to maneuver with great accuracy in fighting games, auto and flight simulators.

Consider the structure of the SCPH-1080 joysticks supplied with the set-top box. They are often called "gamepads" or "joypads" since the game (game) is controlled not by the deflection of the lever (stick), but by pressing on the elastic "pillows" (pads). According to the internal structure, these products can be conditionally divided into ordinary and improved. The former contain one frameless microcircuit, filled with a compound, to which the contacts of all buttons are connected. The clock generator of the microcircuit operates at a frequency of about 200 kHz, the value of its external frequency-setting resistor is 27 ... 91 kOhm. Sometimes a capacitor with a capacity of 200 pF to 0,01 uF is installed on the board.

The improved joystick (its diagram is shown in Fig. 5) is based on the 23-0271A microcircuit from the Japanese company Mitsumi.

The IVP processor polls the state of the buttons 50 times per second during the reverse frame scan of the TV. To do this, it generates signals PE1, PE2, SYN1, SYN2, which are bursts of pulses that repeat with a period of 20 ms. In response, at the output of the joystick OUT2, sync pulses appear with the same frequency, the shape of which does not depend on the state of the buttons, and at OUT1 - a signal similar to that shown in Fig. 6.

Pressed buttons correspond to pulses of negative polarity at certain time positions. By observing this signal on pin 9 of socket X4 of the switching board with an oscilloscope (see Fig. 3), one can judge that the joystick connected to socket X1 is working properly.

The operation of the DD1 chip is clocked by an internal oscillator whose frequency (4 MHz) is stabilized by a piezoceramic resonator (PCR) BQ1 from a solid solution of lead titanate-zirconate. Typical parameters of the RCC of the German company Herbert C. Jauch [6] are as follows: frequency deviation from the nominal at 25°C - no more than +0,5%, frequency drift in the temperature range -20...+80°C - no more than +0,5 .30%, resistance at resonant frequency - no more than 0,3 Ohm, aging coefficient - no more than +10% for 1,5 years. RCCs are 5...4.0 times cheaper than quartz ones for the same frequency and are distinguished by high mechanical strength. The latter is especially important for joysticks and other devices used by children. The disadvantages can be considered reduced frequency stability and quality factor. If necessary, the HCJ-169 RCC installed in the joystick can be replaced with a 4 MHz PK33 quartz resonator and two XNUMX pF capacitors each.

The female connector X1 is connected by a seven-wire cable 2 m long to the plug X2, pins 2 and 7 of which are not used. At a distance of 10 ... 30 mm from the plug there is a collapsible plastic nozzle. Inside it is a ferrite sleeve put on the cable with a diameter of 16 ... 20 and a length of 25 ... 30 mm. By increasing the inductance of the wires passing through it and the magnetic coupling between them, the bushing suppresses the common-mode component of the currents flowing through the cable, which reduces the radiated radio interference. If the sleeve "dangles" inside the nozzle, it can be fixed with glue or a rubber gasket.

The described joystick is manufactured using surface mount technology and is characterized by good oscillator frequency stability, external circuit protection and maintainability. Thanks to the X1 connector, the connecting cable can be disconnected from the printed circuit board for repair or replacement. The contact pads of the SB1-SB14 buttons have a black non-oxidizing carbon coating.

PROCESSOR BOARD

The block diagram of the processor board is shown in fig. 7. Eight blocks are selected on it. The belonging of an element to one of them is determined by the first digit of the number in its reference designation: computing system - 1, videographic - 2, digital data processing - 3, sound channel - 4, video encoder - 5, power supply - 6, CD interface -ROM - 7, adaptation block - 8.

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High performance "PlayStation" provides a central processor having a structure called RISC (Reduced Instruction Set Computer - a computer with a reduced instruction set). Its features are described in detail in [7, 8]. Let us recall the main ones: only elementary operations are provided in the command system; all commands have the same length and structure; microprogram control is replaced by hardware; minimized the number of memory accesses.

In the early 90s, more than a dozen types of 32-bit RISC processors were produced, among them Am29000 (AMD), 88000 (Motorola), Clipper (Fairchild). For "PlayStation" was chosen R3000A, developed by the American company MIPS Computer Systems. The decision was not accidental. Back in April 1991, Sony, Microsoft, NEC, DEC, Siemens, Compaq and several others formed the ACE consortium, which developed a unified approach to the development of computing tools. MIPS RISC processors and the Intel x86 processor family were recommended as the base ones.

The MIPS architecture was developed at Stanford University (USA) in the early 80s as the basis for the onboard computer of the missile defense system [8]. The R3000 processor was announced by MIPS on March 28, 1988. This is a second-generation device, a worthy successor to the famous R2000, one of the first RISC processors to reach the commercial stage. The original R3000 paired with the R3010 coprocessor ran at 25 MHz with a speed of 20 million operations per second, consuming an average of 1,25 cycles for each. The R3010 is often referred to as a co-interpreter. It analyzes and executes its commands in parallel with the central processor, speeding up the operations of addition and multiplication of floating-point numbers by 5...10 times.

In the future, thanks to the improvement of technology, the R3000A processor appeared with a clock frequency increased to 45 MHz. I would like to note that by today's standards he is already an "old man". Literally a year after the "PlayStation" appeared on the market, MIPS developed the 64-bit RISC processor R10000, operating at a frequency of 275 MHz.

The R3000A has a Harvard architecture, i.e. separate instruction and data memory spaces. It is equipped with an internal pipeline, thanks to which it can process up to five commands simultaneously. The principle of operation of the R3000A conveyor is shown in fig. 8.

Each command is executed in five cycles. In the first of them (VC) there is a selection from the memory of the operation code to be performed. In the second (RT), the processor reads from its registers the data necessary to execute the instruction. In the third (OP), the arithmetic logic unit performs the specified operation. Next, data is exchanged with memory (PM) and the result of the operation (ZP) is written to the registers. Since the commands are located on the "threads" of the pipeline with a shift, in each clock cycle all processor nodes are busy with their work, and the execution of one of the commands is necessarily completed. The next one from the program memory is immediately put on the freed "thread".

Unfortunately, such an ideal picture is possible only if the execution of the command does not require the results of the work of the previous ones, which are not yet completed and are on the pipeline. In such cases, you have to waste time waiting for the necessary data. For the R3000A, the losses average 25%. Pipeline idle times are also associated with accesses to external memory. To eliminate them, a fast cache memory is used, which serves as a buffer between the processor and the relatively slow main RAM.

RISC CORE

MIPS, paradoxically, never had its own semiconductor production. Licenses for the right to manufacture RISC processors have been sold to many firms. As already mentioned, the first "PlayStation" models used the R3000A chip from the American company LSI Logic Inc. In later ones, including the one under consideration, a specialized 208-pin VLSI CXD8606AQ from Sony Computer Entertainment Inc. is installed. (SCEI), which includes the processor itself, similar to the R3000A, the R3010A coprocessor, program cache, data cache, bus arbiter and interface nodes (Fig. 9). The CXD8606AQ is clocked at 33,9 MHz for 30 MT/s. The frequency of the clock pulses CLK coming from the integrated crystal oscillator X101' is twice as high as specified. The speed of data exchange on the system bus reaches 132 Mbps.

External dynamic data RAM (IC106) with a capacity of 16 Mbit can consist of one 70-pin A65844 or A67871 chip (Toshiba), or four 28-pin KM48V514DJ-6 (Samsung). The operating system of the video set-top box is "hardwired" in a 32-pin IC102 program ROM (M53403IE-04 or 3030 from SCEI) with a capacity of 4 Mbit. It includes programs for creating musical and graphic screensavers and two menus: a music CD player and a "Memory Card" service. By the way, the design of menus and splash screens in the American and European versions of "PlayStation" is different.

COMPUTING SYSTEM CONNECTORS

The location of the connectors on the back of the "PlayStation" is shown in fig. 10 (contact numbers are given in accordance with their marking on the printed circuit board). The computing system includes plugs CN103 "PARALLEL I/O" and CN104 "SERIAL I/O". In addition, the processor board has a CN102 "JOYSTICK" socket connected by a flexible cable to the switching board inside the set-top box.

On fig. 11 shows the circuit diagram associated with the CN102 socket. There are seven of them in total: four output and three input, the latter being connected to a +1 V power supply through resistors R3-R3,3. polarity. For example, input OUT3 (the name should not be misleading, this joystick output signal is the input signal for the processor) is protected by ferrite filter FL1, diode VD1, resistor R4 and capacitor C1. Inductors L104-L106 suppress interference penetrating the power circuits, they also often perform the functions of fuses, burning out during short circuits.

Small-sized ferrite filters, similar to the mentioned FL1, designed in the form of SMD elements, are widely used in "PlayStation". Their frequency response is monotonous up to frequencies of 100 ... 300 MHz, there are no oscillations ("ringing") in transient processes. These products can be distinguished from other similar ones by the black housing without inscriptions and markings on the printed circuit board starting with the letter F. Typical parameters of Murata Mfg. BLM11 series filters. Co.: size 0603, maximum current - 0,2 ... 0,5 A, active resistance - 0,1 ... 0,7 Ohm, impedance at a frequency of 100 MHz - 60 ... 600 Ohm.

The CN103 parallel port plug is designed to connect high-speed peripherals that require direct access to the processor's system bus. It can be, for example, a module for viewing videos from Video-CD discs. Most of the 68 plug pins are connected to various pins of IC102, IC103, IC305, IC308, IC402, IC602 via 150 ohm resistors. Pins 1, 5, 16, 19, 34, 35, 39, 50, 53 and 68 are GND. The supply voltages through the chokes L110 and L111 are connected to contacts 18, 52 (+7,6 V) and 17, 51 (+3,3 V). Contacts 31 and 65 are free.

The circuit diagram associated with the CN104 serial port plug is shown in fig. 12. All inputs and outputs are protected by diodes VD1-VD6 and filters FL101-FL106, and power circuits are protected by chokes L101 and L102. Input signals (except IN1) are fed to the processor chip through inverters on transistors Q102 and VT2. Output signals (except Q1) are generated by open collector inverters on transistors VT1 and Q103.

The serial port is mainly used to connect two consoles when playing in the "network" mode provided in many programs ("Command & Conquer", "Duke Nukem"). Players fight against each other, each controlling their console. The length of the seven-wire connecting cable (link-cable) is up to several meters. In the absence of a branded one, it can be made according to the scheme shown in Fig. 13. If there are no suitable cable sockets, use the usual "tape" plugs ONTS-VG-11-7/16 (SSh-7). In this case, it will be necessary to equip each of the connected set-top boxes with an SG-7 socket, which should be connected in parallel with the CN104 plug, for example, as shown in fig. 14 (view from nests). Unfortunately, it is difficult to find a place for an additional socket in the processor unit, and it will most likely have to be left hanging on the wiring harness that is brought out to the outside.

VIDEOGRAPHIC SYSTEM

The speed of the videographic system "PlayStation" is 66 million operations per second. The 208-pin IC203 CXD8561 chip from SCEI is responsible for drawing polygons, moving pixel sprites with individual rotation and scaling, and painting image contours with a certain color. 1,5 million uniformly shaded (flatshaded), 500 thousand textured (texture-mapped) or luminous (lightsourced) polygons are processed per second.

The mPD201GF-A481850 chip from NEC is used as video RAM IC12 (Fig. 15). This 8 Mbit dynamic synchronous graphics RAM (SGRAM) consists of two memory banks of 131072 32-bit words each. There are two 32-bit color and mask registers. Memory regeneration occurs automatically in 1024 cycles within 16 ms. SGRAM allows you to change the image on the screen as quickly as possible. By writing certain commands to the control register, you can perform paging and syllabic writing/reading of data, accelerated clearing, masked data processing, and content exchange between memory banks. All operations are performed synchronously on the rising edge of the CLK signal.

The duration of the write / read cycle for mPD481850GF-A12 is 12 ns, the maximum clock frequency is 83 MHz (operating - 67,7376 MHz), the supply voltage is 3 ... 3,6 V, the current consumption is 6 ... 310 mA depending on the mode of operation. KM201G4132BQ-271 (Samsung), mPD10-A481850 (NEC) chips can be installed as IC10.

Chip IC202 TDA8771A (Fig. 16) is a three-channel video DAC from Philips, designed for 24-bit color coding, called TrueColor in computer graphics. Its supply voltage is 4,5 ... 5,5 V, the current consumption is 10 ... 45 mA.

The color components R, G, B are assigned eight bits of the input code, which allows you to reproduce 16777216 color shades. The output voltage of each of the three channels on a load with a resistance of 1 kΩ varies from 0,26 (code 0H) to 3,2 V (code 0FFH). The clock pulse frequency at the VCLK input (pin 31) is 13,3 MHz - exactly four times less than the GCLK frequency received from the X201 crystal oscillator. For a working microcircuit, the voltage at pin 33 (VREF) is in the range of 1,2 ... 1,3 V. Sometimes the MC202FT microcircuit (Motorola) is used as IC141685.

DIGITAL DATA PROCESSING SYSTEM

The data read from the CD is sent to the IC305 decoder (100-pin CXD1815 chip from Sony). Together with IC304' (SC430929PB from Sierra Semiconductor Corp., 52 pins), it receives a serial data stream, extracts frame and bit synchronization signals from it, checks the correctness of the decoded information and corrects errors. It is believed that the accepted method of encoding makes it possible, due to redundancy, to automatically recover lost data in case of scratches on the surface of a CD up to 2,4 mm long.

To service the decoder, a static buffer RAM IC303 with a capacity of 256 Kbps (32K (8) is intended. The UM62256V-10 RAM chip can be replaced with 62W256LTM8, KM62V256CL-10L with an access time of no more than 100 ns. Domestic KR537RU21 cannot be used, since they are not designed for voltage power supply 3,6 V.

The overall speed of the processing system is 80 million operations per second, JPEG (still image transmission), MPEG1 (moving image transmission), H.261 (video conferencing) formats are supported.

The sound processor is IC308 (100-pin CXD2925Q chip from Sony), to which 4 Mbit RAM (40-pin M5M44260CJ chip from Mitsubishi or MB814260-70 from Fujitsu) is connected. Memory organization - 256Kh16.

The musical capabilities of the "PlayStation" allow you to use it as a household CD player by connecting it to a stationary UMZCH or listening to recordings through stereo headphones. The sound quality will more than suit everyone, except maybe fans of high-end equipment. The audio CD service menu provides rewinding, searching for records, programming the order of their playback. You can even listen to the sound clips of game programs.

SOUND CHANNEL

The diagram of the unit for converting digital data into analog form coming from the IC308 audio processor is shown in fig. 17. Its basis is the IC402 AK4309AVM chip from the Japanese company Asahi Kasei Microsystems Co. Ltd. - dedicated two-channel 16-bit delta-sigma DAC. By structure, it is a sequential one-bit. Theoretically, deltasigma modulation is most effective when processing noise-like signals with a uniform spectrum. This explains why inexpensive consumer CD players with these DACs don't play classical music very well, but perform great when listening to expressive rock.

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The main parameters of AK4309AVM: sampling frequency - 44,1 kHz, frequency response unevenness -% 0,5 dB in the frequency range 0 ... 20 kHz, dynamic range - 85 ... 91 dB, crosstalk between channels - 80 ... 90 dB, maximum output voltage - 3,2 ... 3,6 V, power consumption - 80 ... 120 mW at a supply voltage of 4,5 ... 5,5 V. AK4309AVM can be replaced with AK4309VM or AK4310 microcircuits of the same company .

The DAC input receives three signals, the timing diagrams of which are shown in Fig. 18 (LRCK - data switching of the left and right channels, SDATA - serial data, BICK - bit synchronization), as well as MCLK - clock pulses with a frequency of CLK / 4 (16,9344 MHz). The output signals of the left (L-AUDIO) and right (RAUDIO) channels in game programs have an average amplitude of 1,5 ... 2 V.

Transistor keys Q403, Q404 block the sound when the "RESET" button is pressed (the control voltage is supplied through the resistor R7, the diode Q401 and the "digital" transistor VT2). At the same time, the reset signal is sent to the IC9 chip via the R1C402 circuit. The sound is also blocked by a signal from pin 37 of the IC308 chip coming through transistors VT1 and VT2. The voltage divider of resistors R10, R11 sets a potential of about 3,8 V at the emitter of the transistor VT2. Capacitors C407, C443, C2, C3, C5, C6 filter noise.

VIDEO ENCODER

On fig. 19 shows the part of the "PlayStation" circuit responsible for the formation of the television signal. The IC501▓ RGB-PAL encoder is a CXA1645M chip, functionally similar to the CXA1145M used in the Sega Mega Drive-2 IVP. Color signals R, G, B with an amplitude of 501 V, as well as a mixture of vertical and horizontal sync pulses SYNC with TTL levels, come to its inputs through emitter followers on transistors Q503-Q1.

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The CN502 "AV MULTI OUT" plug provides six output signals. VIDEO is a 1,5 V PAL full color video signal. Y-OUT and C-OUT are the luminance and color components of this signal, respectively. (Sometimes they are called S-video or Y / C-video. TVs that have special inputs for them provide higher image quality by eliminating some of the conversions in the television path). R-OUT, G-OUT, B-OUT - video signals of primary colors with amplitude 1...1,5V. Resistors R11-R16 and diodes VD1-VD3, VD6 are protective. Zener diodes VD4, VD5, VD7-VD14 (stabilization voltage 4,7 V), connected in pairs in anti-series, serve as transient limiters and protect the device from electrostatic charges.

All of the outputs listed can be directly connected to 75 ohm loads. This allows you to connect to the video set-top box not only a TV, but also a video monitor. On a black and white TV (monitor) you can send Y-OUT or VIDEO signals, on a color (depending on the model) - VIDEO or R-OUT, G-OUT, BOUT or Y-OUT, C-OUT.

The cable supplied with the set-top box for connection to the CN502 socket ends with three tulip plugs of yellow (VIDEO), red (R-AUDIO) and white (L-AUDIO) colors. Some models of "PlayStation" are equipped with an adapter "euro-scart" (EURO-AV connector plug). The location and purpose of its pins are shown in fig. 20 (unused and usually missing are shown in dashed lines).

If the TV has a stereo sound channel, the red and white plugs of the cable are connected respectively to the inputs of the right and left stereo channels. Higher sound quality will be provided by stereo headphones connected directly to the RAUDIO and L-AUDIO outputs of a game console or a stereo UMZCH with external speakers. The amplifier must be designed for input signals with an amplitude of up to 3,5 V. To connect it, you will have to make an adapter.

Most TVs do not have stereo sound. The game software menu usually allows you to select "MONO"-"STEREO" or "MONO"-"D" to which only one of the stereo channels is connected will be defective.The PlayStation manual recommends in this case to connect the white plug of the left stereo channel to the mono input.In "MONO" mode, the same sum signal is produced at the outputs of the left and right stereo channels and it doesn't matter which one is connected to the TV.

The +6 V voltage (current up to 502 mA) brought out to socket 4,9 of the CN25 socket is designed to power the SCPH-1122RFU external RF modulator, which allows you to send a video set-top box signal to the TV's antenna jack. The modulator is usually not included in the "PlayStation &" package. Instead of the "native" modulator, you can use similar nodes from the "Dendy", "Sega Mega Drive-2" set-top boxes or a home video recorder.

SOURCE OF POWER

Schematic diagram of the power supply of the processor board is shown in fig. 21. CN602 connector circuits are protected by PS601PS605 fuses. In some models, their operation currents can be two to three times greater than those indicated in the diagram. Numerous chokes and capacitors suppress impulse noise penetrating the power circuits. A large number of ceramic blocking capacitors, not shown in the diagram, are installed on the processor board in the immediate vicinity of the power pins of the microcircuits.

(click to enlarge)

Unlike 8- and 16-bit IVPs, PlayStation uses several supply voltage ratings: 7,6; 5; 4,9; 3,6; 3,3 V. From the input voltage of 7,6 V, using the IC601 microcircuit, 5 V is obtained, which the stabilizer on transistors VT2, VT4, VT5 lowers to 3,6 V. A current limiter is assembled on transistors VT1, VT3, which protects the prefix from short circuits in devices connected to the CN502 socket. Short circuit current - 70 ... 80 mA, voltage at the limiter output without load - approximately 4,9 V.

Analog microcircuits of the set-top box are powered by a voltage of 5, and digital ones, including the processor and memory (except for IC310, IC801 ') - 3,3 V. The need for low-voltage power supply of digital integrated circuits arose when the technological standards for designing semiconductor structures became less than 0,7 microns. The intensity of the electric fields inside the crystal has increased so much that at a voltage of 5 V breakdowns have already become possible. In the mid-80s, the JEDEC standard recommended a supply voltage of 3,3V+10%. In "PlayStation" it is usually closer to the upper limit and reaches 3,5 ... 3,55 V. The positive consequences of low voltage power supply are a decrease in power consumption and facilitation of the thermal regime of microcircuits. The winnings reach 50% or more.

The initial reset circuit consists of elements R1-R6, C2, C7. In the initial state, the logic level of the voltage on the RES line is high.

CD-ROM INTERFACE

The wide possibilities of "PlayStation" are associated primarily with the presence of a CD-ROM drive in it. Sound effects, "live" image, three-dimensional animation, dialogue require a huge amount of programs and source data. CD-ROM allows you to work with 650 MB of information (compare with 4 MB in the most capacious cartridges of the "Sega Mega Drive-2" set-top box). Data reading speed - "doubled" (300 Kb/s).

The drive in question is similar to most used in music CD players. Details of its device can be found in [9-11]. As is known, data is recorded on a CD by micropits on the surface of the light-reflecting information layer, which form a continuous spiral track that unwinds from the center of the disk to its periphery. A semiconductor laser in the infrared wavelength range (780 nm) illuminates the track through a lens with a narrow beam of light, which is reflected differently from micropits and gaps between them. The photomatrix receives the reflected modulated light and converts it into electrical signals. The pre-processor, consisting of IC703, IC705' and IC708 chips, amplifies and converts them into a form convenient for further use.

The drive is controlled by a controller based on the IC701 CXD2545Q chip. Functionally, it serves as the basis for several automatic control systems (ACS).

SAR-VD (disk rotation), controlling the engine, maintains a constant linear speed of movement of the information track relative to the reading head (SG). The disk rotation frequency varies from 1000 min-1 when reading data at the beginning of the information spiral, to 400 min-1 at its end. When the lid of the CD container is opened, the CAP-VD will urgently stop the engine.

SPSG (SG positioning system) with the help of a stepper motor moves the SG along the radius of the disk. A worm gear is used to convert rotational motion into translational motion. There is a contact sensor for approaching the SG to the center of the disk. After its operation, further movement of the SG in this direction is blocked.

CAP-PC (radial tracking) ensures that the spot illuminated by the laser beam moves strictly along the center line of the recording track. Its deviation in one direction or another leads to a change in the voltage at the outputs of the photomatrix, which is converted by the controller into a control signal of the corresponding sign, which acts on the lens servo. The tracking accuracy reaches +0,1 µm with a disk rotation eccentricity of +70 µm.

SAR-F (focusing) maintains the same distance between the CD information layer and the lens. It is necessary because the lens has a depth of field of only +1,9 µm, and the beating of the disc surface can be as high as +0,5 mm. To compensate for them, the SAR-F has a large stabilization coefficient at a beat frequency coinciding with the disk rotation frequency. The ability of the video set-top box to read low-quality South Asian discs, the surface curvature of which is often visible to the naked eye, largely depends on the characteristics of this system. The SAR-F control signal also goes to the lens servo.

SAR-ML (laser power) stabilizes the strongly temperature-dependent output power of a semiconductor laser. The power sensor is a built-in photodiode. The main parameters of the laser diodes used are: operating current - 45...110 mA at a voltage of 1,6...2,2 V; maximum radiation power - 3 ... 5 mW (working - 0,4 ... 1 mW); durability - up to 100 thousand hours

On fig. 22 shows a schematic diagram of the CD-ROM drive and its interface circuits with the processor board. Three identical amplification channels of the IC702 chip (BA6392FP from Rohm), specially designed for CD players and CD-ROM drives, control the lens servo (L1, L2) and the SG drive motor (M2), and the fourth differential - the disc rotation motor (M1). Basic parameters of BA6392FP: supply voltage - 6...16 V, quiescent current - 8...18 mA, dissipation power - 1,7 W, load resistance - 8...20 Ohm, output voltage - 1,3.. .5,2 V, gain of the disk rotation channel - 8...13 dB. In the initial state, when the motors are stopped, the voltages at all outputs of the BA6392FP are the same and close to 3,5 V. Depending on the voltage difference at the respective outputs, the motors rotate in one direction or the other.

(click to enlarge)

The M1 motor is controlled in a combined way: roughly - by changing the constant component, precisely - by bursts of pulses of different polarities. The working direction of disk rotation is clockwise (with a positive voltage difference at pins 27 and 26 of IC702). Opening the CD access cover causes emergency braking by applying a reverse polarity voltage to the M1 motor.

The control of the stepper motor M2, which moves the SG, is only pulsed. The contacts of the switch S1 are closed when the SG carriage rests against the limiter. The SPSG receives a signal prohibiting the further movement of the SG.

Filters FB701-FB704 suppress switching noise, Zener diodes VD1-VD4 with a stabilization voltage of 4,7 V limit voltage surges.

The lens servo motor acts like a dynamic speaker driver, in which the voice coil, which is in the field of a permanent magnet, moves under the influence of a flowing current. Windings L1 and L2 of the servo move the lens in mutually perpendicular planes. Their magnetic circuits are permanent magnets made of rare earth alloys. Servo sensitivity reaches 4mm/V.

The laser emitting diode A1 is connected to the collector circuit of the transistor Q701. Rated current - 60...80 mA. The adjustment is carried out by the resistor R1, located on a flexible printed ribbon cable connecting the SG to the CN702 plug, and included in the SAR-ML feedback circuit. As the resistance decreases, the current and laser power increase. The signals taken from the matrix of phototransistors A2 are fed through the coupling capacitors C3-C6 to the IC703 (A1791N) microcircuit. The sensitivity of the device is adjusted by the trimmer resistor RV703.

ADAPTATION UNIT

The purpose of this block is to ensure the operation of the set-top box from both branded and non-branded CDs marked "NTSC U / C" (USA / Canada), "NTSC J" (Japan), PAL (Europe, Asia). Its schematic diagram of the device is shown in Fig. 23. As IC801', the so-called "universal chip" is used - an eight-bit Z86E0208PSC microcontroller from Zilog with a masked 512-byte ROM, into which a program submitted by the customer is entered during manufacture. The clock frequency of 4,433 MHz is equal to the color subcarrier frequency in the PAL system and is set by the Z801' quartz resonator.

The block uses only two outputs of the microcontroller. On the first of them (Q1), a synchronization sequence for the CDROM interface is formed, on the second (Q2), when the power is turned on, a high logic level pulse with a duration of about 1 s is generated.

All elements of the adaptation block are installed on a separate printed circuit board, glued to the back side of the processor board of the set-top box and connected to it by wires. Some "PlayStation" models use Microchip Technology's 86C0208/P microcontroller instead of the Z12E508PSC.

REPAIR OF SUPPLIER

In a branded service center, the repair of a "PlayStation" usually takes no more than 15 minutes - exactly that much time is required to replace faulty boards with obviously good ones. Another thing is amateur conditions and the lack of spare parts.

When starting to repair the "PlayStation", inside which there is a semiconductor laser, it should be remembered that its radiation is dangerous for humans. Of course, this is not the "hyperboloid of engineer Garin" and the power of its radiation is insufficient to damage, say, the skin of the hand, but the eyes are very vulnerable to invisible infrared rays. According to the label on the case, "PlayStation" is classified as a class 1 device for laser safety, which does not pose a threat to health. Indeed, during normal use of the set-top box, its design and electrical interlocks do not allow direct contact with laser radiation in the eyes. Another thing is the repair with the top cover removed. According to the degree of danger, such work is classified as class 2, when precautionary instruction is necessary, but special eye protection is not yet required.

It is strictly not recommended to look into the "peephole" of the laser, especially at close range. At a distance of 20 cm from it, the radiation density is 44 μW/cm2, in the immediate vicinity it is even higher. The lens of the eye, focusing light on the retina, significantly increases the radiation density. For example, with a pupil diameter of 0,5 cm, the power flux density at its focus is 60 times greater than the incident one! Therefore, the retina can be irreversibly damaged even by radiation whose power is considered safe. If necessary, the laser beam should only be observed with an infrared-sensitive night vision device.

Of course, when repairing the "PlayStation", one should not forget about such prosaic things as high voltage on the power board. Even when the game console is turned off with the "POWER" button, the voltage converter works as long as the mains plug is inserted into the socket.

A failed power board can be replaced with a self-made source with two output voltages: 3,3 ... 3,6 V at a load current of at least 0,7 A and 7,4 ... 7,8 V at a load current of at least 1 A. Voltages must be stabilized (preferably with the possibility of adjustment within small limits), have ripples less than 100 mV. The unit must be protected against short circuits. The RES reset signal can be given by any normally open button by connecting it between pins 4 and 5 of connector CN602. In parallel with the button, it is desirable to install a capacitor with a capacity of 1 ... 2,2 microfarads.

The breakout board rarely fails. Most often, its defects are of a mechanical nature. However, if a ribbon cable breaks, you should not try to solder its conductors - they will instantly evaporate. It is better to make a new cable from ordinary thin wires.

Repair of the processor board should begin with the "ringing" of all fuses, inductors, ferrite filters and chip jumpers. Faulty chip resistors can be replaced with domestic R1-4-0,125 W, and chip capacitors with K10-17-4v. If space permits, it is permissible to install ordinary elements, shaping their conclusions accordingly.

Pay attention to connectors CN102 and CN702. They do not withstand repeated "power" docking and undocking. In case of loose connection, carefully tighten the contacts, fasten the articulated parts with an elastic bracket. Docking and undocking of the set-top box connectors with the power supply turned on often leads to failure of protective diodes and zener diodes in various circuits. The exception is the CN103 parallel port connector. In it, the contacts of the power circuits and the common wire are structurally designed in such a way that they are connected first and disconnected last. This guarantees the security of the connection of information circuits.

Next, check the transistors and diodes. The parameters of the semiconductor devices used in the processor board are given in Table. 3, and the location of the terminals of the transistors - in fig. 24. The data is taken from the Siemens catalog, although similar devices from unknown manufacturers are actually installed, sometimes without any markings on the case. "Digital" transistors can not always be checked with an ohmmeter or probe, but in any case, the resistance of the "emitter" junction should be measured. Faulty low-power transistors can be replaced with domestic series KT3129, KT3130. Devices in surface-mounted packages can also be replaced by their counterparts in conventional ones, preferably with tape leads. For example, diodes of the KD102, KD109, KD518 series, transistors of the KT315, KT361 series are suitable.

If the RGBPAL encoder malfunctions, you can try to connect the set-top box to the TV using the R, G, B, SYNC signals (pins 2, 3, 4, 10 of the CXA1645M chip). Interface device options are well known to radio amateurs.

The TA78M05F voltage regulator can be replaced with a more powerful domestic KR142EN5A microcircuit by choosing a copy that works stably at an input voltage of 7,6 V. To facilitate the thermal regime of the BA6392FP microcircuit that controls the CD-ROM drive motors, it is advisable to glue a metal heat sink 40x10 mm in size to its case.

Replacing digital microcircuits of the processor board with domestic ones is practically impossible, since low-voltage logic microcircuits and VLSI, which have no analogues, are mainly used. The op amps can be replaced by almost any op amps operating at 3,6V (IC708) or 7,6V (IC704').

Unstable operation of the CD drive, observed only with some of the discs, usually indicates a poor quality of the latter. Other causes of drive failure are microcracks in the flexible SG cable, lens misalignment, wear of moving parts, drying of the lubricant.

A special case is damage to the optics due to careless handling. Scratches on the lens cannot be repaired. Attempts to wash it with chemically active substances, cologne, various cleaners only lead to clouding of the "lens". It is recommended to clean the lens only with a brush with a very soft pile, and in case of significant contamination - with a clean cotton swab attached to a wooden stick and barely moistened with a liquid for cleaning optical instruments.

When diagnosing faults, it is convenient to use the device shown in Fig. 25. Its basis is a board made of foil fiberglass, at both ends of which small-sized radio elements (capacitors, resistors) are installed, equipped with pins for connecting to the contact pads of the printed circuit board of the device under test. It is advisable to have several similar rods on hand with elements of different ratings, including short-circuit jumpers and small-sized variable resistors. By connecting the rods to various points of the device, you can quickly localize the fault.

CONCLUSION

I would like to note that "PlayStation", in addition to purely gaming use, can serve as a good incentive to learn programming. Discs for "PlayStation" are readable on IBM-compatible computers. In the vast majority of cases, you can view program codes, message texts, and even listen to melodies and speech inserts from games. For example, sound files *.pcm, *.da are reproduced by the standard "Laser Player" program from WINDOWS 95. A large field of activity opens up for the Russification of game programs, the transfer of popular games from other computer platforms, and the development of their own software.

Literature

1. Fedorov A. Turn your computer into a game console: Creative Labs 3DO Blaster. - ComputerPress, 1995, No. 5, p. 140-142.
2. Semiconductor Group. Short Form Catalog 06.96. - Munich, Siemens AG, 1996.
3. Basset D. Switching power sources: development trends. - Electronics, 1988, No. 1, p. 72-77.
4. Konovalov E. Quasi-resonant voltage converter. - Radio, 1996, No. 2, p. 52-55.
5. Suppression of electromagnetic interference in power circuits / Ed. Veksler
6. Electronic components. Catalog. - M.: CJSC "ARKOS", 1998, p. 84.
7. Frunze A. Processors for personal computers. - Radio, 1998, No. 4-6.
8. What will replace the von Neumann architecture? - M.: Knowledge, 1989, No. 5 (series "Computer technology and its application").
9. Nakajima H., Ogawa H. Digital records. - M.: Radio and communication, 1988.
10. Kolesnikov V.M. Laser sound recording and digital broadcasting. - M.: Radio and communication, 1991.
11. Denisenko A., Balabanov A. Compact discs: technologies and standards. - Radio, 1998, No. 6, p. 24-26; No. 7, c26, 27.

Author: S.Ryumik, Chernihiv, Ukraine

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