Jump to content

Panasonic FS-A1FM General Maintenance

From RetroTechCollection
Panasonic FS-A1FM main board
FS-A1FM main board. The T9769 MSX-Engine is at the right of the V9938, the TC8566F floppy controller at the lower left, and the video and audio circuits at the upper left

The Panasonic FS-A1FM is a 1988 MSX2 computer with a built-in modem, a 100 V power supply on its own board and a belt-driven 3.5-inch floppy drive. No Panasonic service manual for it has been found. Its drive is the same as the Panasonic FS-A1F's, so the drive procedures in the Panasonic FS-A1F General Maintenance guide apply to it. The sections below cover what is particular to the FS-A1FM.[1]

Mains supply

[edit | edit source]

The FS-A1FM takes 100 V mains directly and is rated 15 W.[2] Its power supply is on a separate board inside the case.[3] On 220 to 240 V mains, run it from a step-down transformer with a 100 V output. No circuit diagram of the supply has been published. With the case open, the supply board, the mains lead and the power switch are live whenever the machine is plugged in, so unplug it before working inside.

Telephone line

[edit | edit source]

The modem board is connected to the telephone line through the modular socket board, which carries the two sockets and a surge absorber, and a transformer and relay on the modem board.[3] Unplug the telephone lead as well as the mains lead before opening the case.

Opening the case and the floppy drive

[edit | edit source]

The drive is the same as the FS-A1F's and takes the same belt (rubber, 0.3 mm thick, 58 mm in diameter, 3 mm wide).[1] Follow the FS-A1F drive procedure for the belt, the index sensor (unsolder it; never unscrew it) and the heads. The drive's 26-way connector has the same pin-out on both machines.[4] Note the orientation of the drive cable before unplugging it: on the FS-A1F the stripe marks the pin 26 end, not pin 1.[4]

Backup cells and start-up

[edit | edit source]

Two AA cells, type R6P (SUM-3), in a compartment in the base keep the clock and settings.[2] The MSX Resource Center recommends lithium cells or Eneloop rechargeables and advises against alkaline cells, which leak in time.[1] Take the cells out of a machine going into storage; see Battery Explosion, Capacitor or Corrosion Damage if they have leaked.

The built-in communication software starts at power-on. The switch at the back skips it and leaves the modem working; holding DEL during start-up skips it and also switches the modem off.[1]

Memory upgrade

[edit | edit source]

The main RAM can be taken from 64 KB to 128 KB:[5][1]

  1. Fit two 64K × 4 DRAMs in ZIP packages, such as the MB81464-12, at IC17 and IC18.
  2. Fit 0.1 µF ceramic capacitors at C71 and C72.
  3. Short jumper J2 and cut jumper J3. They are between the VDP and the T9769.
  4. Check the result with a memory test that reports the memory mapper size, which should read 128 KB.

The FS-A1F's upgrade uses different positions and needs no jumper change, so instructions written for the FS-A1F do not apply.[5]

Capacitors

[edit | edit source]

See the Panasonic FS-A1FM Capacitor Replacement Guide.

Supply checks

[edit | edit source]

Measure the rails at a cartridge slot: +5 V on pins 45 and 47, +12 V on pin 48 and −12 V on pin 50, with pins 41 and 43 as ground.[6]

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 Panasonic FS-A1FM, MSX Resource Center wiki, 7 March 2026—link(accessed 2026-10-21) Community page: built-in modem (300/1200 bit/s) with two RJ11 sockets for the line and a telephone; 8 KB SRAM (NEC D4364CX-15L) used mainly by the modem software; firmware switch at the back skips the firmware at start-up without deactivating the modem, while holding DEL at start-up skips it and deactivates the modem; with a Sunrise CF/IDE interface, redefine the DEL key with IDKEYSET.COM or use its BIOS 2.50b; RAM upgradable to 128 KB with two vertical MB81464-12 DRAMs and two 100 nF capacitors, cutting J3 and making J2, between the VDP and the T9769; drive belt rubber, 0.3 mm thick, 58 mm diameter, 3 mm wide; gallery captions "Panasonic FS-A1F/FS-A1FM drive" and "FS-A1F/FS-A1FM drive PCB"; lithium or Eneloop backup cells recommended, alkaline advised against.
  2. ↑ 2.0 2.1 Underside of an FS-A1FM: rating label "電源入力 AC 100V 50/60Hz 15W", Part No. T0129ZA; backup cell label giving R6P (SUM-3), two cells; telephone equipment approval label 認定番号 S88-3019-0. File:Panasonic FS-A1FM underside and rating label.jpg, from the MSX Resource Center wiki (uploaded by Mars2000you, 16 September 2020).
  3. ↑ 3.0 3.1 FS-A1FM– up-c, 2011, updated 2022—link(accessed 2026-10-21) In Japanese. Annotated photographs: power switch and power cable on the side; at the back, the line and telephone modular sockets, RGB, printer, cassette, audio and video outputs, the built-in software on/off switch, the RF channel switch and the RF output; inside, the floppy drive, the power supply board, the RF module and the main board; the modem board with its transformer and relay, USART and PPI; the modular connector board with the sockets and a surge absorber.
  4. ↑ 4.0 4.1 FS-A1Fの改造 前編– niga2—link(accessed 2026-10-21) In Japanese. Drive connector pin-out given for the "Panasonic FS-A1F/FM"; the stripe on the main board's cable is on the pin 26 side, not pin 1.
  5. ↑ 5.0 5.1 FS-A1FM MSX-ENGINEとメインRAM– up-c, 2011, updated 2022—link(accessed 2026-10-21) In Japanese. Two 64K × 4 bit DRAMs in ZIP packages sit under the T9769 MSX-Engine; the empty positions IC17 and IC18 take two more (MB81464), with 0.1 µF decoupling capacitors at C71 and C72; the extra memory was not recognised until jumper J2 was shorted and J3 cut; the FS-A1F and FS-A1FM boards are completely different, and the DRAM package differs.
  6. ↑ MSX Cartridge slot, MSX Resource Center wiki, 6 July 2026—link(accessed 2026-10-21) Pins 41 and 43 GND, 45 and 47 +5 V, 48 +12 V, 50 −12 V.



Retrieved from "https://retrotechwiki.com/index.php?title=Panasonic_FS-A1FM_General_Maintenance&oldid=28330"