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Panasonic CF-2700 General Maintenance

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Panasonic CF-2700 main board, German model
Main board of a German CF-2700 (DFUP0007ZBJ-1). The supply section with its large reservoir capacitors is at the top left

The Panasonic CF-2700 is a one-piece MSX1 computer from 1985 with its keyboard and mains power supply inside the case.[1] Matsushita's service manual for the export model (Panasonic CF-2700 Service Manual) is the source for the disassembly order, the supply and video adjustments and the self test given here. Boards changed between batches, so check designators against your own board before relying on them; the Panasonic CF-2700 page lists the known differences.

Mains safety

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The mains lead runs through the power switch SW101 on the left side of the case to the power source board, which carries a line filter (L101 with C101 and C102) and a T160mA fuse and feeds the transformer T101. The main board has a T3.15A fuse in the +5 V output.[2] The export machine runs on 220 V, or 240 V for the United Kingdom, at 28 W.[3] The power switch and the lead carry mains whenever the plug is in, and the power source board and the transformer primary carry it whenever the machine is switched on.[4] Unplug the machine before opening it, and keep clear of the switch, the power source board and the transformer whenever it has to run open.

The manual's self test asks for at least 30 seconds between switching the computer off and switching it on again.[5]

Opening the case

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The manual's order of work is below.[6]

  1. Unplug the mains lead and every cable.
  2. Remove the three 3 × 6 mm screws marked (A) in Fig. 28.
  3. Lift the top cabinet far enough to reach CN5 on the main board. Press the top of the connector and unplug the micro switch cable.
  4. Pull the top cabinet away in the direction of Fig. 29.
  5. For the keyboard, remove its two 3 × 6 mm screws, pull the keyboard back, and unplug its two flat cables from CN8 and CN9. Hold each cable by both sides of its stiffened end.
  6. For the main board, remove five 3 × 10 mm screws and one 3 × 8 mm screw. Press the latch on CN1 and unplug it, unplug CN2 by pressing its top, and lift the board out.
  7. For the video board, remove the 3 × 8 mm screw holding the shield plate and pull the plate off. Remove the board's two 3 × 10 mm screws, release the two latches in the bottom cabinet and lift the board.
  8. For the power source board, remove its 3 × 8 mm screw, unplug CN101 and CN102 (each has a latch), and pull the board out.
  9. For the slot micro switches, remove the 3 × 10 mm screw and the two switches. The slot panel comes off after its four latches are released, and the slot cover after that.

Refit the micro switch cable with its white lead on pin 1 of CN5, and the video board cable with its white lead on pin 9 of CN2.[6] The latches on the bottom cabinet and the slot panel break if forced.[6]

Cleaning

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Keyboard

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The keyboard is a separate assembly on two flat cables. The parts list gives individual switch units and key tops.[7] Reseat CN8 and CN9 only by the stiffened ends of the cables.[6]

Cartridge slots and slot switches

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Each slot has a sprung cover and a micro switch.[7] The switches are wired into the PSW line that turns +5 V and +12 V on, so a dirty contact can stop the machine from starting at all.[8][9] With the top cabinet off, work the switch levers by hand and check with a meter that each normally closed contact reads near 0 Ω. Clean a contact that does not with switch cleaner, or replace the switch. Clean the slot contacts with isopropyl alcohol on a lint-free swab, and clean the edge connector of each cartridge before blaming the slot.

Connectors and boards

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CN1 (the transformer secondary), CN2 (the video board), CN5, CN101 and CN102 are plug-in connectors.[6][10] Unplug and refit each one to clean the contacts, and look for cracked solder joints at the regulators, the fuse clips and the connector pins. Blow dust out of the boards with dry compressed air.

Supply checks and adjustment

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Measure the rails at a cartridge slot with no cartridge fitted:[11]

Supply rails at a cartridge slot
Rail Slot pins (to pin 41) Expected Load allowed per pin
+5 V 45, 47 4.97 to 5.03 V after adjustment 300 mA
+12 V 48 +12 V 50 mA
−12 V 50 −12 V 50 mA

The +5 V figure is the adjustment window in the manual. The −5 V rail is not on the slot; the supply diagram marks a test point on it.[2][12]

To set +5 V:

  1. Connect a meter between pin 45 (positive) and pin 41 (ground) of slot 1, CN7.
  2. Switch on.
  3. Turn VR1 on the main board until the meter reads between 4.97 and 5.03 V.[12]

VR1 sets the +5 V reference by dividing down +12 V, so check +12 V first; if +12 V is wrong, VR1 cannot correct +5 V.[2] Leave VR1 alone if +5 V is already inside the window.

The general ports supply +5 V at up to 50 mA on pin 5.[11]

Video adjustments

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Both adjustments are on the video board.[12]

  • Colour clock: put a frequency counter on pin 9 of IC203, with pin 7 as ground, and turn trimmer CT201 for 4.43361875 MHz ±3 Hz.
  • RF channel: tune the television to UHF channel 35, 36 or 37 (583.25, 591.25 or 599.25 MHz) and turn the channel trimmer at the back of the computer for a clear picture.

Composite video from the video socket avoids the RF stage altogether.[13]

Electrolytic capacitors

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All of the supply electrolytics are on the main board; the power source board has only two 0.1 µF capacitors in its line filter.[7][2] Advice on the MSX Resource Center forum is to replace the main supply's capacitors whatever their condition, to judge the audio and video capacitors by the picture and sound, and to replace one capacitor at a time using the service manual's parts list.[14] The list and positions are in the Panasonic CF-2700 Capacitor Replacement Guide.

Self test

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Panasonic's self test runs from test cartridge DFWV95C0001 and checks the VDP and video RAM, RAM, PSG, keyboard, ROM, screen, cassette input and output, joystick, printer and audio output. It needs an MSX printer, a joystick, a television and a cassette recorder.[5] Without the cartridge, check the same functions by hand: the MSX-BASIC prompt, a cartridge in each slot, a recording saved and loaded at 1200 baud, both joystick ports and a printer if you have one.

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References

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  1. ↑ Panasonic CF-2700 (UK), MSX Resource Center wiki, 7 March 2026—link(accessed 2026-10-21) The National CF-2700 rebranded for the British, Dutch and Spanish markets in 1985; one unit with keyboard and power supply built in; two cartridge ports at the top right, the nearer one being slot 2.
  2. ↑ 2.0 2.1 2.2 2.3 Matsushita, Service Manual: Personal Computer CF-2700 (order no. IED84113035C2, 1984), printed pages 18 and 19, "Power Supply Circuit", with the diagram on page 19 (File:Panasonic CF-2700 power supply circuit.png). Power source block: SW101, C101 and C102 (0.1 µF), L101, T160mA fuse; transformer T101 with 5 V, 5 V, GND, 12 V, 12 V secondary connections to CN1 on the main board. Main board: +5 V from D7 and D8, reservoir C11 (16 V 6800 µF), pass transistor Q1 (2SA1061P), driver Q7 (2SC1318-Q), error amplifier Q8 and Q2 (2SA722-S), VR1, T3.15A fuse, C18 (10 V 330 µF); +12 V from D3 and D5, C10 (25 V 4700 µF), IC1 AN7812R, C7 (16 V 330 µF); −12 V from D4 and D6, C6 (25 V 1000 µF), IC2 AN7912T, C12 (16 V 100 µF); −5 V from −12 V through R31 (470 Ω) and R36 (680 Ω). PSW held at ground lets +5 V and +12 V run; left open, both fall to about 0 V while −12 V and −5 V stay on. Test points (TP) are marked on the +12 V, −5 V and −12 V outputs. See Panasonic CF-2700 Service Manual.
  3. ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 1, "Specifications": 220 V 50 Hz (only for UK 240 V 50 Hz), 28 W; 436 × 245 × 90 mm, about 3.6 kg. See Panasonic CF-2700 Service Manual.
  4. ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 42, "Wiring Connection Diagram": the mains lead (blue and brown) goes through the power switch to CN101 on the power source board; CN102 on that board feeds the transformer primary. Printed page 19: SW101 is drawn switching both mains conductors. See Panasonic CF-2700 Service Manual.
  5. ↑ 5.0 5.1 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed pages 21 to 32, "Self Test". Equipment: the CF-2700, an MSX printer or plotter, joystick CF-2201, a television, test cartridge part no. DFWV95C0001, a cassette recorder and tape; the test program starts at 8000H from a 16 KB ROM in the slot; twelve checks (program start, VDP/VRAM, printer, RAM, PSG, keys, ROM, screen display, cassette I/O, joystick, print-out, audio output); keep the cassette recorder at least 30 cm from the TV; step 24 note: do not turn the power on immediately after turning it off, wait at least 30 seconds. See Panasonic CF-2700 Service Manual.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed pages 34 to 38, "Disassembly Instruction", Figs. 28 to 40. Top cabinet: three 3 × 6 screws (A, Fig. 28), the micro switch cable (B) from CN5, pull the cabinet away (Fig. 29); unplug CN5 by pressing the top of the connector, and refit with the white lead on pin 1. Keyboard: two 3 × 6 screws (Fig. 30), lift the keyboard, unplug its cables from CN8 and CN9 holding both sides of the reinforced portion (Fig. 31). Main board: five 3 × 10 screws and one 3 × 8 screw (Fig. 32), unplug CN1 (press the latch) and CN2, pull the board out (Fig. 33); unplug CN2 by pressing its top and refit with the white lead on pin 9. Video board: shield plate held by one 3 × 8 screw (Fig. 34); the board by two 3 × 10 screws (Fig. 35) and two latches of the bottom cabinet (C, Fig. 36), unlatched without excessive force. Power source board: one 3 × 8 screw, sockets CN101 and CN102 (Fig. 38). Micro switches: one 3 × 10 screw (A) and the two switches (B) (Fig. 39); slot panel held by four latches (C), then the slot cover (Fig. 40); take care not to break the slot panel latches. See Panasonic CF-2700 Service Manual.
  7. ↑ 7.0 7.1 7.2 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed pages 64 to 67, "Replacement Parts List". Keyboard block: power LED LN220RP (D301), Caps LED LN88RCPP (D302), 73 key tops (DFWV70C0001 to DFWV70C0073), flexible pattern assembly DFWV48A0008, switch units FBM-652 series (55 for A, B, C and the like, 4 cursor, 10 function and others). Cabinet block: two slot covers K1, two slot springs K2, two micro switches K5 (FBM-438-008). Power source block: C101 and C102 ECQE2A104M (0.1 µF), no electrolytic capacitors. See Panasonic CF-2700 Service Manual.
  8. ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 44, "Schematic Diagram (Main Board)": the normally closed contacts of "SWITCH SLOT 1" and "SWITCH SLOT 2" in series from ground (CN5 pin 1) to CN5 pin 3, which is the PSW line and also goes to SW1 (pin 44) of a slot connector; CN5 pin 2, between the two switches, goes to SW2 (pin 46). See Panasonic CF-2700 Service Manual.
  9. ↑ Panasonic CF-2700, October and November 2025—link(accessed 2026-10-21) sdsnatcher73 (30 October 2025): the CF-2700 has protection switches in the slots; if they are dirty or corroded the machine senses a cartridge being inserted and the power supply stays off until two pins are shorted in the connector; clean the switches in both slots. Jipe (28 October 2025): check the two micro switches on the slots.
  10. ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 42, "Wiring Connection Diagram": transformer T101 to CN1 (+5 V, +5 V, GND, +12 V, +12 V); video board to CN2 (1 GND, 2 SOUND, 3 R−Y, 4 B−Y, 5 Y, 6 CLK, 7 +5 V, 8 +12 V, 9 −12 V); micro switches to CN5 (1 GND, 2 SLOT 1, 3 SLOT 2); keyboard to CN8 and CN9; mains through the power switch to CN101 and the transformer primary to CN102 on the power source board; slot 1 CN7, slot 2 CN6. See Panasonic CF-2700 Service Manual.
  11. ↑ 11.0 11.1 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 41, "Slot 1 and Slot 2": card edge, 50 pins at 2.54 mm; 41 and 43 GND, 45 and 47 +5 V (load 300 mA or less), 48 +12 V (50 mA or less), 50 −12 V (50 mA or less); 44 SW1, 46 SW2, 49 SUNDIN. Printed page 40: general ports pin 5 +5 V, 50 mA or less. See Panasonic CF-2700 Service Manual.
  12. ↑ 12.0 12.1 12.2 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 39, "Adjustment". Power source: adjust VR1 so that the DC voltage at pin 45 of connector CN7 is 4.97 to 5.03 V, measured against pin 41. Clock frequency: frequency counter on pin 9 of IC203 on the video board (pin 7 ground); adjust trimmer capacitor CT201 for 4.43361875 MHz ±3 Hz. Channel adjust trimmer: set the TV to UHF channel 35 to 37 (583.25, 591.25 or 599.25 MHz) and adjust for a clear picture, or set it with a spectrum analyser on the RF output. See Panasonic CF-2700 Service Manual.
  13. ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed pages 3 and 4, "Location of Controls and Components": sound output, video output and RF output jacks and the channel adjust trimmer at the rear; power switch on the left side. See Panasonic CF-2700 Service Manual.
  14. ↑ Recap recommendations, June 2018—link(accessed 2026-10-21) RetroTechie, 23 June 2018: supply bypass electrolytics spread over the board can often be removed without the machine stopping; those in the audio and video circuits show their condition in the output; those in the main power supply are worth replacing whatever their condition; compare the service manual's parts list with the board and replace capacitors one at a time. Wlcracks: use Rubycon, Chemi-Con, Nichicon or Panasonic.



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