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National CF-3000 Capacitor Replacement Guide

From RetroTechCollection
National CF-3000 inside
Inside the CF-3000 main unit. The power supply board in the metal box at the right carries the four large electrolytic capacitors

No parts list or capacitor list for the National CF-3000 has been published, and no service manual for it has been found.[1][2] The values have to be read from the boards. The one published photograph of the inside shows where the electrolytics are, but at 1200 pixels across the printing on them cannot be read.[3]

What the photograph shows

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  • The power supply sits at the right of the main unit, on a board inside an open-topped metal box. It carries four large electrolytic capacitors and an aluminium heat sink plate, and a coloured harness joins it to the main board. The mains transformer is mounted in front of the box.[3]
  • The main board has only a handful of small electrolytics; the rest of its capacitors are small ceramic types.[3]
  • The keyboard is a separate unit; its inside has not been photographed in a published source.[1]

Which to replace first

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Advice on MSX recapping from the MSX Resource Center forum is to replace the main power supply's capacitors whatever their condition, to judge the audio and video capacitors by the output, and to leave the small decoupling capacitors unless there is a reason.[4] On the CF-3000 that means:

  1. The four large capacitors on the power supply board.
  2. Any other electrolytics on that board.
  3. Electrolytics near the video and audio outputs, if the picture or sound is poor.
  4. The rest, only if they show leakage or bulging, or a rail is noisy.

For comparison only, the export Panasonic CF-2700, a one-piece Matsushita MSX with a different supply, uses 6800 µF at 16 V, 4700 µF at 25 V and 1000 µF at 25 V for its +5 V, +12 V and −12 V reservoirs.[5] Do not order parts for the CF-3000 from those figures; read its own capacitors.

Recording the board

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  1. Pull the mains plug out of the wall, unplug the keyboard and anything on the rear outlet, and open the main unit as described in the National CF-3000 General Maintenance guide.
  2. Photograph the power supply board from above and from each side; the metal box hides part of it.
  3. Photograph each electrolytic close up so the printing on the sleeve can be read.
  4. For each capacitor, write down the designator, the capacitance, the voltage, the diameter and height, and which side the stripe faces.
  5. Order replacements of the same capacitance and at least the same voltage, in a size that fits inside the box.
Template for the CF-3000's list
Ref Value Voltage Diameter × height Board Notes
Power supply
Power supply
Power supply
Power supply

Procedure

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  1. Note how the harness joins the power supply board, whether by plug or by solder, and which way round, then free the board and lift it out of its box. Its fixings have not been documented, so photograph them first.
  2. Replace one capacitor at a time, with the stripe on the same side as the original. Working one at a time avoids mixing up values or polarity.[4]
  3. Clean any electrolyte from the board and check the tracks round the large capacitors for corrosion.
  4. Refit the board and the harness, and close the unit.

After the recap

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Switch on and measure the rails at a cartridge slot: pins 45 or 47 for +5 V, 48 for +12 V and 50 for −12 V, all against pin 41.[6] Then check that MSX-BASIC starts with the keyboard working, that a cartridge runs in each slot, and that the picture and sound are clean on composite video. Remaining faults are covered in the National CF-3000 Troubleshooting Guide.

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References

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  1. ↑ 1.0 1.1 National CF-3000, MSX Resource Center wiki, 13 April 2019—link(accessed 2026-10-21) Community specification page: one case with a separate keyboard (numeric keypad; the photograph is captioned "CF-3000/3300 keyboard"), NEC D780C-1 (Z80A), 64 KB of RAM in slot 1, TMS9928A video, AY-3-8910 PSG, no MSX-Engine, an eject button for each cartridge slot, no space for a floppy drive; connections listed as RF output, composite video and sound output, "RGB21 output (not Scart)", keyboard connector, Centronics connector for the optional CF-2601 superimpose unit, data recorder connector, Centronics printer port, two general (joystick) ports, two cartridge slots and an AC 100 V power outlet; main unit 428 × 96 × 285 mm, keyboard 426 × 40 × 159 mm, 6.8 kg; gallery photographs of the front, back, label and inside, and of the left side, which shows two 9-pin ports and a round socket.
  2. ↑ Index of /pub/msx/docs/service_manuals, MSX Archive—link(accessed 2026-10-21) Directory of MSX service manuals; the Panasonic and National entries are the CF-2700 and the turbo R machines.
  3. ↑ 3.0 3.1 3.2 File:National CF-3000 inside.jpg, photograph of the inside of the CF-3000 main unit uploaded to the MSX Resource Center wiki by Mars2000you, 31 August 2020. Read from it: the main board fills the left and centre, with the printer, keyboard and superimpose connectors along the rear edge, the cartridge connectors along the front, and only a handful of small electrolytics; the power supply sits at the right in an open-topped metal box holding a board with four large electrolytic capacitors and an aluminium heat sink plate, joined to the main board by a coloured harness; the mains transformer is bolted to the floor in front of it.
  4. ↑ 4.0 4.1 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.
  5. ↑ 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. ↑ 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.



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