Panasonic FS-A1ST
 | |
| FS-A1ST on display, with a cartridge in the top slot (photograph by Tilemahos Efthimiadis, CC BY-SA 2.0) | |
| Specifications | |
|---|---|
| Manufacturer | Matsushita Electric Industrial (Panasonic) |
| Type | MSX turbo R home computer |
| Released | November 1990[1] |
| Intro price | ¥87,800 excluding tax[2] |
| CPU | R800, with a Z80A-compatible CPU[2] |
| Memory | 256 KB main RAM, 128 KB video RAM, 16 KB SRAM; 1.5 MB ROM[2] |
| Storage | 3.5-inch double-sided drive, 720 KB formatted[2] |
| Display | Yamaha V9958[2] |
| Sound | PSG in the T9769 MSX-Engine, YM2413 FM (MSX-MUSIC), PCM[2] |
| Power | AC 100 V ±10 %, 50/60 Hz, 21 W; two AA cells for backup[2] |
| Dimensions | 425 × 292 × 89 mm[2] |
| Weight | 3.4 kg[2] |
| OS / Firmware | — |
| Successor | Panasonic FS-A1GT |
| Model no. | FS-A1ST |
The Panasonic FS-A1ST is an MSX turbo R computer that Matsushita Electric Industrial released in Japan in November 1990 under the Panasonic name. It has the 16-bit R800 processor alongside a Z80A-compatible processor for older software, 256 KB of main RAM, a V9958 video processor, MSX-MUSIC, PCM recording and playback, a built-in 3.5-inch drive and a Japanese word processor in ROM.[2] Panasonic was the only maker of turbo R machines, which were sold only in Japan; the FS-A1ST was followed by the Panasonic FS-A1GT.[1]
Specifications
[edit | edit source]| Item | Figure |
|---|---|
| CPU | R800, with a Z80A-compatible CPU |
| ROM | 1.5 MB: Kanji BASIC 4.0, Disk BASIC, MSX-MUSIC BASIC, 16-dot font, MSX-JE dictionary, word processor |
| RAM | 256 KB main, 128 KB video, 16 KB SRAM (backed up) |
| Video | V9958 |
| System controller | T9769 MSX-Engine (PSG, RTC, keyboard, printer and joystick ports) |
| FM sound | YM2413 |
| Drive | 3.5-inch 2DD, 1 MB unformatted, 720 KB formatted |
| Interfaces | Two cartridge slots, printer, two general-purpose ports, S-video, composite video, audio, RGB, RF |
| Supply | AC 100 V ±10 %, 50/60 Hz, 21 W; DC 3 V from two AA cells for backup |
| Size and weight | 425 × 292 × 89 mm, 3.4 kg |
[2] The machine has no cassette connector. It has six indicator lamps: power, caps lock, kana lock, pause, CPU mode and drive in use.[1]
Hardware
[edit | edit source]The mains transformer, the keyboard, the drive, the LED board and the switch board are separate; everything else, the power supply included, is on the main board.[3][4] The Technical Guide's parts list gives these main ICs:[5]
| Position | Part | Function |
|---|---|---|
| IC28 | R800 | 16-bit CPU |
| IC27 | S1990 | System IC |
| IC17 | T9769C | MSX-Engine |
| IC16 | V9958 | Video processor |
| IC21 to IC24 | 1464-12 | Video RAM |
| IC30, IC32 | MN41C4256-08 | Main RAM |
| IC25, IC26 | 5165 | SRAM, backed up by the AA cells |
| IC12, IC18 | Mask ROMs | 4 Mbit and 8 Mbit |
| IC10 | YM2413 | FM sound (MSX-MUSIC) |
| IC7 | TC8566AF | Floppy disk controller |
| IC6 | CXA1145 | Video encoder for composite, S-video and RF |
| IC14 | MC34063 | DC/DC converter for +5 V |
| IC11, IC13 | C24M12HF, AN7912T | +12 V and −12 V regulators |
[5][6] The parts list gives four crystals: X1 16 MHz, X2 32.7 kHz, X3 28.6 MHz and X4 21.47 MHz. The Technical Guide's checks take the floppy controller's clock from X1 and the R800's clock from X3.[5][7]
Power supply
[edit | edit source]The transformer's centre-tapped secondary reaches the main board at CN1. D2 and D3 charge the reservoir capacitor C50 (25 V, 12000 µF), which feeds both the +5 V switching converter and the +12 V regulator. The +5 V converter is built round IC14 (MC34063) and transistor Q1, with a crowbar (zener D9 and thyristor D1) across its output. IC11 regulates +12 V; D4, D5 and C59 feed IC13 for −12 V.[4][5] Alexandre Souza of Tabajara Labs found the same supply in the FS-A1FX, FS-A1WX, FS-A1WSX, FS-A1ST and FS-A1GT, with only the switching transistor differing.[8]
Backup cells
[edit | edit source]The SRAM holds the word processor's learning dictionary and the settings made with BASIC's SET commands. It and the clock run from two AA cells when the machine is off, and Panasonic shipped the machine without the cells fitted.[9]
Known problems
[edit | edit source]- The drive belt perishes. Owners report belts that melted onto the pulleys, and a melted belt can stick and block the mechanism.[10][11] See Panasonic FS-A1ST General Maintenance.
- The MSX Resource Center advises against alkaline backup cells because they leak sooner or later, and recommends lithium cells or Eneloop rechargeables.[1]
- In a 2007 report, C50 (25 V, 12000 µF) ran very hot and then smoked on a machine whose transformer had been replaced with a 220 V one.[12]
- In a 2025 case, a 6.3 V 1000 µF capacitor on the YM2413's supply failed short circuit; the machine also needed a new voltage regulator before it would start.[13]
- The 512 KB RAM upgrade that some machines carry can fail; one owner's took out an address line of the S1990.[11]
- The audio mixing is badly set from the factory: slot sound too loud, FM too quiet and over-filtered. A published modification changes six surface-mount parts.[14]
Documentation
[edit | edit source]Panasonic's Technical Guide for the FS-A1ST, in Japanese, is described on the Panasonic FS-A1ST Technical Guide page. It has the disassembly procedure, pass/fail checks with expected voltages and waveforms, circuit diagrams and the parts lists.
Repair guides
[edit | edit source]- Panasonic FS-A1ST General Maintenance
- Panasonic FS-A1ST Troubleshooting Guide
- Panasonic FS-A1ST Capacitor Replacement Guide
Gallery
[edit | edit source]-
The R800 at IC28 (photograph by Yaca2671, CC BY-SA 3.0) -
Power supply circuit from the Technical Guide -
Disassembly page of the Technical Guide
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Related pages
[edit | edit source]- Panasonic FS-A1GT, the later turbo R
- Panasonic FS-A1WX and Panasonic FS-A1WSX, MSX2+ machines with the same supply design
- Panasonic FS-A1ST Technical Guide
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 Panasonic FS-A1ST, MSX Resource Center wiki, 14 August 2026—link(accessed 2026-10-21) Community page: released November 1990 in Japan at ¥87,800; Panasonic was the only maker of MSX turbo R computers, which were sold only in Japan; succeeded by the FS-A1GT; 256 KB RAM in slot 3-0 and 16 KB SRAM; Toshiba T9769C and ASCII S1990; TC8566AF floppy controller; six LEDs (power, caps lock, kana lock, pause, CPU mode, drive in use); no cassette connector; drive belt rubber, 0.3 mm thick, 58 mm diameter, 3 mm wide, sold as Panasonic FW-U1P501J; original drive flat cable Sumitomo AWM 2896, 100 mm long, 1.25 mm pitch; links to a 512 KB RAM upgrade and to replacing the internal supply with a 230 V one; recommended backup batteries lithium or Eneloop; alkaline advised against "because they leak one day or another".
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Matsushita Electric Industrial Co., Technical Guide: Personal Computer FS-A1ST, February 1991, cover (printed page 1): features and specification. Features: R800 16-bit CPU, with a Z80-compatible CPU for existing software; word processor with voice guidance; 256 KB main RAM and 128 KB video RAM; MSX-DOS2 as standard; PCM recording and playback. Specification: AC 100 V ±10 %, 50/60 Hz; DC 3 V from two AA dry cells for backup; 21 W; CPU R800 with a Z80A-compatible CPU; ROM 1.5 MB (MSX Kanji BASIC version 4.0 80 KB, MSX Disk BASIC 64 KB, MSX-MUSIC BASIC 16 KB, 16-dot font ROM 256 KB, MSX-JE dictionary ROM 512 KB, word processor ROM 608 KB); RAM 400 KB (main 256 KB, video 128 KB, SRAM 16 KB for backup); display controller V9958; system controller T9769 (MSX-Engine: PSG, RTC, keyboard, printer and general-purpose ports); FM sound YM2413; 92-key keyboard; 3.5-inch double-sided double-density drive, 1 MB unformatted, 720 KB formatted; two cartridge slots, printer port, two general-purpose ports, S-video, composite video, audio, RGB and RF outputs; 425 × 292 × 89 mm; 3.4 kg; standard price ¥87,800 excluding tax. Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ Technical Guide: FS-A1ST, printed pages 10 and 11, disassembly. Upper cabinet: five screws (A) on the underside, then connectors CN12 and CN14. Keyboard: three screws (B), slide it to the left while lifting, unplug the flexible cables from CN10 and CN11. Keyboard flex pattern: 18 screws on the back of the keyboard; keep dust out. Drive: four screws (C), unplug CN19 and the flat cable from CN13. Main board: with the upper cabinet, keyboard and drive removed, two screws (D) on the underside, two screws (E), five (F) and three (G); unplug CN1 and CN17. LED board: three claws (H). Operation panel: claws (I). Switch board: two screws (J). Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ 4.0 4.1 Technical Guide: FS-A1ST, printed page 22: circuit diagram of the main board power section, LED board and switch board. AC 100 V through the double-pole power switch to the transformer. The secondary reaches the board at CN1: pin 1 is the centre tap (0 V), pins 2 and 3 the two ends, all through choke block L5. D2 and D3 charge C50 (25 V, 12000 µF), which feeds both the DC/DC converter and the +12 V regulator. DC/DC converter IC14 (MC34063) with Q1 (2SA1598), R36 (0.2 Ω, 1/2 W), R37 (100 Ω, 2 W), D8, L6 (220 µH), C10 (10 V, 4700 µF) and feedback resistors R96 (3.09 kΩ, 1 %) and R182 (1 kΩ, 1 %); L2 (20 µH) to the +5 V line, with zener D9, R217 (1 kΩ) and a thyristor from +5 V to ground. IC11 (C24M12HF) for +12 V with C51 and C42 (16 V, 100 µF) and L9 (220 µH). D4 and D5 charge C59 (35 V, 470 µF) for IC13 (AN7912T), −12 V, with C60 and C41 (16 V, 100 µF) and L10 (220 µH). D7 and D6 from the +12 V and −12 V lines to ground. DC voltages printed on the diagram include Q1 emitter 20.4 V, base 20.3 V, collector 5.2 V; IC14 pins 6 and 7 20.4 V, pin 5 1.2 V; IC11 input 20.5 V. Hosted as File:Panasonic FS-A1ST Technical Guide.pdf. The power section is reproduced as File:Panasonic FS-A1ST power supply circuit (Technical Guide).png.
- ↑ 5.0 5.1 5.2 5.3 Technical Guide: FS-A1ST, printed pages 37 to 40, electrical parts list. IC6 encoder CXA1145; IC7 floppy disk controller TC8566AF; IC8 LM324; IC10 FM sound YM2413; IC11 regulator C24M12HF; IC12 mask ROM (4 Mbit); IC13 regulator AN7912T; IC14 DC/DC converter MC34063; IC15 reset IC MN1280R; IC16 VDP V9958; IC17 MSX-Engine T9769C; IC18 mask ROM (8 Mbit); IC21 to IC24 video RAM 1464-12; IC25 and IC26 SRAM 5165; IC27 system IC S1990; IC28 16-bit CPU R800; IC30 and IC32 main RAM MN41C4256-08; Q1 2SA1598; D1 thyristor 5P4M; D2 and D3 30D1F; D4 to D7 RA1501A; D8 SB350; D9 zener DTZ5R6; crystals X1 16 MHz, X2 32.7 kHz, X3 28.6 MHz, X4 21.47 MHz; connectors CN1 power (3-pin), CN13 drive (24-pin), CN17 backup battery (2-pin), CN19 external microphone (3-pin). Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ Technical Guide: FS-A1ST, printed page 13, video checks: enter COLOR 15,15,15 in BASIC; R, G and B at IC16 (VDP) pins 22, 23 and 24, composite sync at IC16 pin 6; R, G and B into encoder IC6 at pins 21, 22 and 23; IC6 sync output at pin 11 and composite output at pin 20. The VDP's RGB goes to the encoder and through a clamp to the RGB connector; the encoder makes the composite signal for the video output and the RF modulator; S-video luminance is amplified by Q6 to Q9 and chrominance by Q2 to Q4. Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ Technical Guide: FS-A1ST, printed page 12, pass/fail checks. Power: +5 V from the DC/DC converter, ±12 V from regulators. +5 V at the collector of Q1, 5 V ±0.25 V. +12 V: IC11 input about +21 V, output +12 V ±1.2 V. −12 V: IC13 input about −22 V, output −12 V ±1.2 V. Clock waveforms: CPU clock at IC16 pin 8; VDP clock at IC16 pin 64; RTC clock at IC17 pin 20; FDC clock at the upper terminal of X1; OPLL clock at IC10 pin 8; 16-bit CPU clock at X3 pin 1. Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ A fonte do MSX Turbo-R (e dos FX, WX e WSX tambem!)– Alexandre Souza, 9 July 2018—link(accessed 2026-10-21) The supplies of the Panasonic machines in the turbo R style case (FS-A1FX, WX, WSX, ST, GT) are all the same apart from the switching transistor Q1, and a 2SA1643 seems to suit all of them; ±12 V from 7812 and 7912 regulators, which rarely fail; when the 5 V supply fails, the MC34063 and the transistor are the likely causes, though a resistor under the board can go open or the crowbar can short; the crowbar is a thyristor triggered by D9, a 5.6 V zener, and fires if, for example, R96 or R182 in the feedback to MC34063 pin 5 goes open; remove L2 (the small bare-copper inductor about 1 cm across) to isolate the supply and the crowbar, and do not remove L6 (the large green inductor) or the output rises to 22 V because the feedback is cut; with L2 out, up to 5.2 to 5.3 V is acceptable; the FS-A1GT under repair had a burnt 5P6J thyristor, replaceable with a TIC112, and the SMD 5.6 V zener under the board can be replaced with a leaded one; if the voltage is still wrong, check for about 22 V at MC34063 pin 6 and at the transistor's emitter, and if it is missing look for a burnt track from D2 and D3.
- ↑ Technical Guide: FS-A1ST, printed page 5, in-service notes: the built-in software switch on the front panel (on, the main menu starts at power-on unless a ROM cartridge is fitted; off, BASIC starts); the backup RAM holds the word processor's learning dictionary and the settings made with BASIC's SET commands, and it and the clock run from two AA dry cells, which are not fitted at the factory; the date and time are set with SET DATE and SET TIME. Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ Turbo-R Panasonic floppy drives, December 2017 to March 2018—link(accessed 2026-10-21) Edevaldo: on an FS-A1ST and an FS-A1GT the original belts had melted in place and stuck to everything; after new belts the drives spun and sought track 0 but gave "disc offline"; cleaning the pulleys with isopropyl alcohol and cotton buds removed a lot of black residue and quietened the drives. gdx: had the same error after a belt change and after long disuse, and the drive worked again straight after a head-cleaning disk. Grauw: tried a couple of belts before one fitted; others were too narrow and would not stay on the pulley, or not tight enough. Manuel: belts last about ten years; Colemu: his lasted five. Moniz: old rubber left on the pulley made a new belt come off.
- ↑ 11.0 11.1 Looking for someone who can (help) repair my Panasonic A1ST TurboR, January 2026—link(accessed 2026-10-21) An FS-A1ST that had worked when stored gave, after several years on a shelf, a black screen, no drive activity and no keyboard response, with one LED lit. Pat: C10 is the buffer capacitor for the +5 V line; measure the supply lines first. meits and Omega: the brown deposit by the 4700 µF capacitor is glue, not leaked electrolyte. Omega: the supply is unlikely to be the cause since the power LED lights; a black screen on a turbo R more likely means bad RAM or a failed custom chip. gdx: check the connector with yellow wires and the big black capacitor, and check the drive belt, which has probably melted and can stick and block the mechanism. meits: see what happens with a game cartridge fitted. Jipe: the machine has a 512 KB RAM modification; check the solder and wiring of the four RAM chips. sdsnatcher73: such an upgrade can cause this; one of his own failed over time and took out an address line on the S1990.
- ↑ New Problem Turbo R A1ST Smoked :o, August 2007—link(accessed 2026-10-21) CrazyBoss: on an FS-A1ST whose transformer had long before been replaced with a 220 V one, the large 25 V 12000 µF capacitor next to the supply became very hot and then smoked; he measured 21 V from the centre pin to each outer pin of the transformer, 42 V across the outer pins. Jipe: a 35 V 15000 µF part is fine as a replacement; the capacitor filters the supply before the regulators; he had fitted 220 V transformers with two 15 V windings to five turbo R machines without trouble.
- ↑ Turbo R ST not powering up (no 5+V either), October and November 2025—link(accessed 2026-10-21) alali.ahmed.t traced a short circuit to a failed 6.3 V 1000 µF capacitor connected to the YM2413, replaced it and recapped the board, but still had no +5 V. Jipe: check for about 15 V AC between CN1 pins 1 and 2 and between pins 1 and 3, and about 20 V DC across C50, measuring everything from the negative of C50; test diodes with one leg unsoldered (about 0.5 V one way); check that L5 is not open. The owner measured 18.7 V from pin 1 to pins 2 and 3 and 37.7 V between pins 2 and 3. kamiboy and sdsnatcher73 on replacement capacitor ratings (sdsnatcher73: stay close to the original voltage, never lower). Wierzbowsky: check the voltages given in the Technical Guide, then D2 and D3, the zener D9, D1 and D7, Q1 and then the DC/DC converter. The owner later reported the machine working after replacing several parts, including a faulty voltage regulator.
- ↑ MSX hardware fixes and enhancements—link(accessed 2026-10-21) Section 2.2, Panasonic MSX turbo R audio fix: slot sound too loud, OPLL too quiet, OPLL and output low-pass filters too strong, output level too weak. For the FS-A1ST: C48 and C49 1.8 nF, R24 22 kΩ, R23 15 kΩ, C57 180 pF, C159 150 pF; all 0805 SMD; capacitors polyphenylene sulphide film or C0G ceramic.