Panasonic FS-A1FM Troubleshooting Guide
No Panasonic fault-finding guide or circuit diagram for the Panasonic FS-A1FM has been found, and few repairs to it have been published. Its floppy drive is shared with the Panasonic FS-A1F, whose drive faults are covered in the Panasonic FS-A1F Troubleshooting Guide. For access to the board, the backup cells and the memory upgrade see the Panasonic FS-A1FM General Maintenance guide.
Things that are not faults
[edit | edit source]- The built-in communication software starts at every power-on. The switch at the back skips it with the modem still working; holding DEL during start-up skips it and switches the modem off.[1]
CALL TELCOMworks from BASIC only if the modem was left active at start-up; after a start with DEL held down it is not available.[1]- Applications on the utility disk return to the MSX-DOS prompt when closed; type
TOOLto get the disk's menu back.[1] - With a Sunrise CF/IDE interface fitted, holding DEL at start-up also disables its partitions. Redefine the key with IDKEYSET.COM or use the interface's BIOS 2.50b.[1]
Fault table
[edit | edit source]| Symptom | Check first | Notes |
|---|---|---|
| Nothing at all, no power lamp | 100 V mains, then the power supply board | Rated AC 100 V, 15 W.[2] The supply is on its own board.[3] |
| No picture, no colour or a poor picture | The video circuits at the upper left of the main board and their electrolytics | The photographed board has no HIC-1 daughterboard; the video circuits are on the main board.[4] |
| Disk does not turn, or read errors | Drive belt, then the heads | The drive and belt are the same as the FS-A1F's; see FS-A1F floppy drive faults.[1] |
| Memory upgrade not recognised | Jumpers J2 and J3 | The upgrade needs J2 shorted and J3 cut as well as the two DRAMs and capacitors.[5] |
| Clock loses the time, settings lost | Backup cells and their contacts | Two AA cells, R6P (SUM-3).[2] |
| Modem software reports no line, or the modem does not dial | The telephone lead, the modular socket board and the modem board's relay and transformer | The modem works at 300 and 1200 bit/s.[1][3] |
Dead machine
[edit | edit source]The FS-A1FM takes 100 V mains directly; there is no external adapter.[2] On 220 to 240 V mains it needs a step-down transformer. With the case open, the power supply board, the mains lead and the power switch are live whenever the machine is plugged in.
- Measure +5 V at a cartridge slot (pins 45 and 47, ground on 41 and 43) and ±12 V on pins 48 and 50.[6]
- If the rails are missing, unplug the machine, take out the power supply board and inspect it, starting with its electrolytic capacitors.[3] On the FS-A1F, niga2 found the electrolytics on the supply board leaking and corroding the tracks.[7] Whether the FS-A1FM uses the same supply board has not been documented, so check yours for the same fault.
No circuit diagram of the FS-A1FM supply has been published. The RBSC group's TinyPSU, designed for the FS-A1F, runs from an external 9 to 12 V adapter and is offered for other MSX machines; mounting parts for the FS-A1FM have not been published.[8]
Floppy drive faults
[edit | edit source]The FS-A1FM's drive is the same as the FS-A1F's, so the belt, head and replacement-drive notes in the FS-A1F guide apply. The drive connector's pin-out published by niga2 is given for both machines.[1][7]
Related pages
[edit | edit source]- Panasonic FS-A1FM
- Panasonic FS-A1FM General Maintenance
- Panasonic FS-A1FM Capacitor Replacement Guide
- Panasonic FS-A1F Troubleshooting Guide
- Capacitor Failure Symptoms
- Floppy Drive Repair
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Panasonic FS-A1FM, MSX Resource Center wiki, 7 March 2026—link(accessed 2026-10-21) Community page: firmware launched at boot, skipped by holding DEL until a beep, which also deactivates the modem; the switch at the back skips the firmware without deactivating the modem; from BASIC, CALL TELCOM reaches the modem settings and phone book only if the modem was not deactivated at boot; emulators do not support the modem; the utility disk's applications return to the MSX-DOS prompt when closed, and TOOL relaunches the menu; CTRL+STOP at boot with the utility disk in drive A avoids its menu; with a Sunrise CF/IDE interface, redefine DEL 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; drive belt 0.3 mm thick, 58 mm diameter, 3 mm wide; shared drive with the FS-A1F.
- ↑ 2.0 2.1 2.2 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. File:Panasonic FS-A1FM underside and rating label.jpg, from the MSX Resource Center wiki (uploaded by Mars2000you, 16 September 2020).
- ↑ 3.0 3.1 3.2 FS-A1FM– up-c, 2011, updated 2022—link(accessed 2026-10-21) In Japanese. Annotated photographs of the inside: the power supply board, the RF module, the floppy drive, the main board areas (VDP and VRAM, slots, FDC and ROM, gate array, MSX-Engine and main RAM), the modem board with its transformer and relay, USART and PPI, and the modular socket board with a surge absorber.
- ↑ File:Panasonic FS-A1FM main board.jpg, photograph uploaded to the MSX Resource Center wiki by Gdx on 11 December 2015: the V9938, T9769 and TC8566F, with the video and audio circuits on the main board at the upper left and no daughterboard.
- ↑ FS-A1FM MSX-ENGINEとメインRAM– up-c, 2011, updated 2022—link(accessed 2026-10-21) In Japanese. DRAMs at IC17 and IC18 and 0.1 µF capacitors at C71 and C72 were fitted, but the memory was not recognised until J2 was shorted and J3 cut; the FS-A1F's method does not apply because the boards are completely different.
- ↑ 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.
- ↑ 7.0 7.1 FS-A1Fの改造 前編– niga2—link(accessed 2026-10-21) In Japanese. On the FS-A1F's switching supply the navy-blue Matsushita electrolytics had leaked brown electrolyte onto the board and begun to corrode the tracks; all were replaced with low-ESR types.
- ↑ Installing TinyPSU power supply into Panasonic FS-A1F, 8 February 2026—link(accessed 2026-10-21) Wierzbowsky (RBSC): the TinyPSU, run from an external 9 to 12 V adapter, installed in an FS-A1F with 3D-printed parts; compatible with the FS-A1F and other MSX computers; project files at github.com/RBSC/TinyPSU.
