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National FS-1300 General Maintenance

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National FS-1300
National FS-1300, with the cartridge slots at the top right

The National FS-1300 is a one-piece MSX1 computer from the end of 1985 with its keyboard and power supply built into the case.[1][2] Its rating label gives AC 100 V, 50/60 Hz, 24 W.[3] No service manual for the FS-1300 has been found. It uses the case of the CF-1200 and CF-2700,[2] and Panasonic's service manual for the export CF-2700 is held on the wiki as the Panasonic CF-2700 Service Manual. The procedures here follow that manual. Its part numbers and designators belong to the export CF-2700, so check them against the FS-1300 board before relying on any of them.

Mains supply

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  • The FS-1300 is built for 100 V mains.[3][4] On 220 to 240 V mains, run it from a step-down transformer with a 100 V output, rated comfortably above the 24 W on the label.
  • The power switch is on the left-hand side of the case.[2]
  • The export CF-2700 in the manual has a 220 V or 240 V transformer, a T160mA fuse on its power source board and a T3.15A fuse in the +5 V line on the main board.[5] A Japanese CF-2700 photographed inside has its supply on a separate board with a 1 A fuse and a transformer labelled "100V 14.7V 27VA".[6] Which arrangement the FS-1300 follows has not been published, so look before ordering a fuse.

Opening the case

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National CF-2700 inside, Japanese model
A Japanese CF-2700 in the same case: power supply board at the left, main board at the right

The export CF-2700 comes apart in this order:[7]

  1. Unplug the mains lead and all cables.
  2. Remove the three 3 × 6 mm screws shown as (A) in Fig. 28 of the manual.
  3. Lift the top cabinet a little and unplug the micro switch cable from CN5 on the main board, pressing the top of the connector as you pull it.
  4. Pull the top cabinet away in the direction shown in Fig. 29.
  5. For the keyboard, remove its two 3 × 6 mm screws, lift it, and unplug its two flat cables from CN8 and CN9. Hold both sides of the stiffened end of each cable as you pull it.
  6. For the main board, remove five 3 × 10 mm screws and one 3 × 8 mm screw, unplug CN1 (press the latch first) and CN2, and lift the board out.

When refitting the micro switch cable, the white lead goes to pin 1 of CN5.[7] The two micro switches are wired to CN5 as GND, SLOT 1 and SLOT 2.[8] Photograph each step on the FS-1300, as its screw positions have not been documented.

Cartridge slots

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The two slots sit side by side at the top right of the case.[1] The slot pinout is part of the MSX standard, and the export CF-2700's slots are described as conforming to it.[9] Clean the contacts of a cartridge with isopropyl alcohol on a lint-free cloth before blaming the slot.

The slots are also the easiest place to measure the supply rails without dismantling anything:[10]

MSX cartridge slot supply pins
Pin Signal
41, 43 Ground
45, 47 +5 V
48 +12 V
50 −12 V

The −5 V rail does not appear on the slot; on the export CF-2700 it is taken from −12 V by a resistor divider on the main board.[5]

Power supply

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On the export CF-2700, the supply gives four rails: +5 V from a discrete regulator round Q1, +12 V from an AN7812R, −12 V from an AN7912T, and −5 V from −12 V. The +5 V output is set by VR1: adjust it for 4.97 to 5.03 V at pin 45 of slot 1 (CN7), measured against pin 41.[5][11] The Japanese CF-2700's supply board carries a preset marked VR101.[6] Measure the FS-1300's +5 V at the slot first. If it is inside 4.97 to 5.03 V, leave the preset alone.

On the export model the +5 V and +12 V rails also depend on a PSW line. While PSW is held at ground both rails run; if it is open, both fall to about 0 V while −5 V and −12 V stay on.[5] The National FS-1300 Troubleshooting Guide uses this to narrow down a dead machine.

Electrolytic capacitors

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The main supply's reservoir capacitors are the ones worth replacing as routine. The small decoupling capacitors spread round the board can often be removed without the machine stopping.[12] The export CF-2700's list, and how to record the FS-1300's own, are in the National FS-1300 Capacitor Replacement Guide.

Video and connections

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The rear panel carries, from the left, the printer port, the cassette socket and the audio and video outputs, with the RF output and its channel switch below them; the two joystick ports are on the right-hand side.[2][4] The FS-1300 uses a TMS9918.[1] The export CF-2700 has a TMS 9929A and a separate video board with a colour-clock trimmer set to 4.43361875 MHz;[9][11] that adjustment does not apply to the FS-1300. On the Japanese CF-2700, the video and audio sockets are on the main board.[6]

Cassette

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MSX machines record by FSK at 1200 or 2400 baud.[9] Test the cassette interface with a known good recording at 1200 baud before suspecting the board.

Self test

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Panasonic's self test for the CF-2700 runs from a test cartridge, part number DFWV95C0001, and checks the VDP and video RAM, RAM, PSG, keyboard, ROM, cassette, joystick, printer and audio output.[13] The cartridge is not part of the scan, and its use on an FS-1300 is undocumented.

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References

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  1. ↑ 1.0 1.1 1.2 National FS-1300, MSX Resource Center wiki, 14 April 2019—link(accessed 2026-10-21) Community specification page: one unit with the keyboard and power supply built in, two cartridge slots side by side at the top right, 64 KB of RAM in slot 3, TMS9918 video, PSG given as an AY-3-8910A (possibly inside an MSX-Engine, marked uncertain); described as the same machine as the CF-1200 or CF-2700 with more RAM.
  2. ↑ 2.0 2.1 2.2 2.3 ナショナル最後のMSX(1)「FS-1300」, Impress, 1 May 2025—link(accessed 2026-10-21) In Japanese. The last National-brand MSX1, released at the end of 1985 in the case of the CF-1200 and CF-2700, with "64K" printed on the top; rear panel from the left: printer port, cassette (CMT) socket, audio and video outputs, and below them the RF output and the channel switch; two joystick ports on the right-hand side and the power switch on the left-hand side; CF-2211 joystick in the box; weight about 3.6 kg.
  3. ↑ 3.0 3.1 Rating label of the FS-1300, photographed for the MSX Resource Center wiki (File:National FS-1300 rating label.jpg, uploaded by Mars2000you, 5 September 2020): "電源入力 AC100V 50/60Hz 24W", 松下電器産業株式会社, Made in Japan.
  4. ↑ 4.0 4.1 National FS-1300 MSX, Centre for Computing History—link(accessed 2026-10-21) Japanese machine on 100 V mains; two joystick ports, two cartridge slots, printer port, built-in power supply, cassette socket, composite video, mono sound, RF output and a two-channel switch.
  5. ↑ 5.0 5.1 5.2 5.3 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed pages 18 and 19, "Power Supply Circuit", with the circuit diagram on page 19. See Panasonic CF-2700 Service Manual. A dropper supply for +5 V, −5 V, +12 V and −12 V with a line filter in the primary; +5 V rectified by D7 and D8 and regulated by Q1 (2SA1061P), Q7 (2SC1318-Q) and the error amplifier Q8 and Q2 (2SA722-S), set by VR1, through a T3.15A fuse; +12 V from D3 and D5 and IC1 (AN7812R); −12 V from D4 and D6 and IC2 (AN7912T); −5 V from −12 V through R31 (470 Ω) and R36 (680 Ω). The diagram gives C11 16 V 6800 µF, C18 10 V 330 µF, C10 25 V 4700 µF, C7 16 V 330 µF, C6 25 V 1000 µF, C12 16 V 100 µF, a 16 V 100 µF capacitor on −5 V, C38 50 V 3.3 µF and C1 50 V 1 µF. The PSW terminal held at ground lets +5 V and +12 V run; left open, Q9 (2SC1685-Q) turns on, current flows from pin 4 of IC1, and +5 V and +12 V fall to about 0 V while −5 V and −12 V stay on. R38 and C38 delay the rise of +5 V and +12 V; R37 discharges C38. The text calls the +5 V smoothing capacitor C7, which disagrees with the diagram.
  6. ↑ 6.0 6.1 6.2 File:National CF-2700 inside, Japanese model.jpg, photograph of the inside of a Japanese CF-2700 uploaded to the MSX Resource Center wiki by Gdx on 30 October 2015. Read from it: a separate power supply board marked DFUP0002ZA-1 at the left, carrying the mains inlet and line filter, a 1 A fuse, three large reservoir capacitors, diodes D101, D102 and D105, IC101, Q103 and a preset VR101, with the transformer (label "100V 14.7V 27VA", DDT5U7J01Z-W) above it; a coloured wiring harness from that board to the main board, marked DFUP0001ZA-1; the composite video and audio sockets on the main board itself.
  7. ↑ 7.0 7.1 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed pages 34 and 35, "Disassembly Instruction". See Panasonic CF-2700 Service Manual. Top cabinet: three 3 × 6 screws (A, Fig. 28), unplug the micro switch cable (B) from CN5 by pressing the top of the connector, then pull the top cabinet away; when refitting, the white lead goes to pin 1 of CN5. Keyboard: two 3 × 6 screws, then unplug the keyboard cables from CN8 and CN9, holding both sides of the reinforced end. Main board: five 3 × 10 screws and one 3 × 8 screw, unplug CN1 (press the latch) and CN2, then lift the board out.
  8. ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 42, "Wiring Connection Diagram". See Panasonic CF-2700 Service Manual. Two micro switches wired to CN5 (GND, SLOT 1, SLOT 2); the transformer secondary (5 V, 5 V, GND, 12 V, 12 V) to CN1; the video board to CN2, which carries +5 V, +12 V and −12 V; the keyboard to CN8 and CN9; cartridge slot 1 is CN7 and slot 2 is CN6.
  9. ↑ 9.0 9.1 9.2 Matsushita Electric Trading Co., Service Manual: Personal Computer CF-2700, order no. IED84113035C2, 1984, printed page 1 (specifications). Hosted here as Panasonic CF-2700 Service Manual. Export model: Z-80A, 64 KB main RAM, TMS 9929A, cassette by FSK at 1200 or 2400 baud, two slots "conforming to MSX specifications", 220 V 50 Hz (240 V for the U.K.), 28 W. Printed page 15, "Cassette Interface Circuit": "MSX uses FSK method for recording, whose transfer rate supports 1200 baud and 2400 baud".
  10. ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 14, Table 7 "Explanation of Signal Lines" for the cartridge slots: pins 41 and 43 ground, 45 and 47 +5 V, 48 +12 V, 50 −12 V, 49 sound input, 44 and 46 SW1 and SW2. See Panasonic CF-2700 Service Manual.
  11. ↑ 11.0 11.1 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 39, "Adjustment". See Panasonic CF-2700 Service Manual. Power source: adjust VR1 for 4.97 to 5.03 V DC at pin 45 of CN7, with pin 41 as ground. Clock frequency: adjust CT201 on the video board for 4.43361875 MHz ±3 Hz at pin 9 of IC203. Channel trimmer: UHF channels 35 to 37.
  12. ↑ Recap recommendations, June 2018—link(accessed 2026-10-21) Reply by RetroTechie, 23 June 2018: in an MSX, the electrolytics used for supply bypassing round the board can often be removed without the machine stopping, those in the audio and video circuits show their condition in the output, and those in the main power supply are worth replacing whatever their condition; use the service manual's parts list and compare it with the board, and replace one capacitor at a time. Other replies recommend Rubycon, Chemi-Con, Nichicon or Panasonic parts from established distributors.
  13. ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed pages 21 to 32, "Self Test". See Panasonic CF-2700 Service Manual. Twelve checks run from the test cartridge, part no. DFWV95C0001, starting at 8000H: the program start, VDP and VRAM, printer, RAM, PSG, keyboard, ROM, screen display, cassette input and output, joystick, print-out and audio output.



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