Panasonic CF-2700 Capacitor Replacement Guide
The Panasonic CF-2700 has its electrolytic capacitors on the main board and the video board. Matsushita's service manual for the export model lists every one of them with a Panasonic part number, and its power supply diagram prints the value and voltage of each supply capacitor.[1][2] Boards changed during production, so read your own board before ordering parts. The German board shown here, for example, has a position marked C84, which the manual's list does not contain.[3]
Before you start
[edit | edit source]- Unplug the computer. The power switch carries mains whenever the plug is in, and the power source board and the transformer whenever the machine is switched on.[2]
- The power source board has no electrolytic capacitors. Its only capacitors are C101 and C102, 0.1 µF each, in the line filter.[1]
- Advice on the MSX Resource Center forum is to replace the capacitors of the main power supply whatever their condition, to judge the audio and video capacitors by the picture and sound, and to replace one capacitor at a time against the service manual's parts list.[4] Look for bulging tops, electrolyte on the board and dark rings round the leads; see Capacitor Failure Symptoms.
Supply capacitors
[edit | edit source]These sit on the main board, between the transformer connector CN1 and the regulators.[2] The voltage column is as printed on the supply diagram; the fifth and sixth characters of each Panasonic part number (1A for 10 V, 1C for 16 V, 1E for 25 V, 1H for 50 V) agree with it for every capacitor in this table that has a part number. The same code gives the ratings in the later tables, with 0J for 6.3 V.[2][1]
| Ref | Value | Voltage | Part number | Position |
|---|---|---|---|---|
| C11 | 6800 µF | 16 V | ECEA1CU682 | +5 V reservoir, after D7 and D8, before pass transistor Q1 |
| C18 | 330 µF | 10 V | ECEA1AU331 | +5 V output |
| C1 | 1 µF | 50 V | ECEA1HV010 | In the +5 V regulator, at driver transistor Q7 |
| C10 | 4700 µF | 25 V | ECEA1EU472 | +12 V reservoir, at the input of IC1 (AN7812R) |
| C7 | 330 µF | 16 V | ECEA1CU331 | +12 V output |
| C6 | 1000 µF | 25 V | ECEA1EU102 | −12 V reservoir, at the input of IC2 (AN7912T) |
| C12 | 100 µF | 16 V | ECEA1CU101 | −12 V output |
| C38 | 3.3 µF | 50 V | ECEA1HU3R3 | With R38, delays +5 V and +12 V at switch-on |
| "C14" on the diagram | 100 µF | 16 V | Not in the parts list | −5 V output, after the R31 and R36 divider |
Two points in the manual do not agree with each other. The circuit description calls the +5 V smoothing capacitor C7, but the diagram and the parts list put C11 there and C7 on the +12 V output. The diagram labels the −5 V capacitor C14, but the parts list gives C14 as a 0.1 µF capacitor (ECFF1E104ZF).[2][1] Read the board for the −5 V position.
Other main board electrolytics
[edit | edit source]The parts list gives these values but the manual's text and figures place only C13.[1]
| Ref | Value | Rating from part number | Part number | Position |
|---|---|---|---|---|
| C13 | 22 µF | 10 V | ECEA1AU220 | Reset timing, with R26[5] |
| C83 | 4700 µF | 16 V | ECEA1CU472 | Not shown in the manual |
| C19, C24 | 100 µF | 10 V | ECEA1AU101 | Not shown in the manual |
| C71, C72, C73, C74 | 100 µF | 10 V | ECEA1AU101 | Not shown in the manual |
| C64 | 10 µF | 16 V | ECEA1CU100 | Not shown in the manual |
If the machine does not start reliably from cold, check that RESET at the CPU rises about 60 ms after switch-on, and check C13 and R26.[5]
Tantalum capacitors
[edit | edit source]Four tantalum capacitors are listed. The manual describes three as 22 µF and one as 220 µF, and the circuit figures agree: Fig. 7 marks C52 "22 µ 10 V" at the video chip and C28 "220 µ 16 V" among the video RAMs, and Fig. 8 marks C55 "22 µ 10 V" at the sound chip.[1][6] Read in the usual three-digit code, the part numbers ECSF1AE225 and ECSF1EE226 give 2.2 µF and 22 µF instead.[1] Read the marking on the part before ordering a replacement.
| Ref | Part number | Value in the parts list | Figure in the manual | Position |
|---|---|---|---|---|
| C52 | ECSF1AE225 | 22 µF | 22 µ 10 V (Fig. 7) | Video chip IC38 supply |
| C28 | ECSF1EE226 | 220 µF | 220 µ 16 V (Fig. 7) | Video RAM supply |
| C55 | ECSF1AE225 | 22 µF | 22 µ 10 V (Fig. 8) | PSG IC36 supply |
| C20 | ECSF1AE225 | 22 µF | Not shown | Not shown in the manual |
Video board electrolytics
[edit | edit source]The video board carries the PAL encoder, the colour-clock trimmer and the output sockets.[1] Its capacitors affect the picture and sound, so judge them by the output.[4]
| Ref | Value | Rating from part number | Part number |
|---|---|---|---|
| C220 | 1000 µF | 6.3 V | ECEA0JU102 |
| C218 | 470 µF | 16 V | ECEA1CU471 |
| C224 | 100 µF | 10 V | ECEA1AU101 |
| C206, C207 | 47 µF | 10 V | ECEA1AU470 |
| C201, C202, C205, C208, C215, C217, C225 | 10 µF | 16 V | ECEA1CU100 |
| C203, C210 | 0.47 µF | 50 V | ECEA1HUR47 |
The manual does not give positions for these.[1]
Recording your own board
[edit | edit source]- Open the case as described in the Panasonic CF-2700 General Maintenance guide, and take out the main board and the video board.
- Read the board marking. The manual's export board has eight DRAMs (IC11 to IC18) and eight video RAMs (IC49 to IC56); a board with two of each is a later revision.[1][3]
- Photograph each board from above, then each electrolytic close up so its printed value can be read.
- Write down for each capacitor the designator, capacitance, voltage, diameter, height and the side its stripe faces.
- Compare the list with the tables here, and go by the board where they differ.
Replacing them
[edit | edit source]- Work on one capacitor at a time, so values and polarity cannot be mixed up.[4]
- Use the same capacitance and at least the same voltage, in a size that fits the space.
- Fit each new part with its stripe on the same side as the old one.
- Clean any electrolyte off the board, and look at the tracks under the large capacitors for corrosion.
- Refit the boards, CN1, CN2 and CN5, and the keyboard cables.
Checks after the work
[edit | edit source]Switch on and measure at a slot, against pin 41: +5 V on pins 45 and 47, +12 V on pin 48 and −12 V on pin 50. Set +5 V to between 4.97 and 5.03 V at pin 45 of CN7 with VR1 if it has moved.[7] Measure −5 V at its test point on the main board.[2] Then check the MSX-BASIC screen, the colour on a PAL television, and the sound. Remaining faults are covered in the Panasonic CF-2700 Troubleshooting Guide.
Related pages
[edit | edit source]- Panasonic CF-2700
- Panasonic CF-2700 General Maintenance
- Panasonic CF-2700 Troubleshooting Guide
- Panasonic CF-2700 Service Manual
- National FS-1300 Capacitor Replacement Guide
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Matsushita, Service Manual: Personal Computer CF-2700 (order no. IED84113035C2, 1984), printed pages 64 to 67, "Replacement Parts List". Main board aluminium electrolytics (ECEA series): C1 ECEA1HV010 1 µF; C6 ECEA1EU102 1000 µF; C7 ECEA1CU331 330 µF; C10 ECEA1EU472 4700 µF; C11 ECEA1CU682 6800 µF; C12 ECEA1CU101 100 µF; C13 ECEA1AU220 22 µF; C18 ECEA1AU331 330 µF; C19 and C24 ECEA1AU101 100 µF; C38 ECEA1HU3R3 3.3 µF; C64 ECEA1CU100 10 µF; C71, C72, C73 and C74 ECEA1AU101 100 µF; C83 ECEA1CU472 4700 µF. Tantalum (ECSF series): C20, C52 and C55 ECSF1AE225, described as 22 µF; C28 ECSF1EE226, described as 220 µF. C14 ECFF1E104ZF, 0.1 µF. Video board: C201, C202, C205, C208, C215, C217 and C225 ECEA1CU100 10 µF; C203 and C210 ECEA1HUR47 0.47 µF; C206 and C207 ECEA1AU470 47 µF; C218 ECEA1CU471 470 µF; C220 ECEA0JU102 1000 µF; C224 ECEA1AU101 100 µF. Power source board: C101 and C102 ECQE2A104M, 0.1 µF. See Panasonic CF-2700 Service Manual.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed pages 18 and 19, "Power Supply Circuit", with the diagram on page 19 (File:Panasonic CF-2700 power supply circuit.png). Values printed on the diagram: C11 16 V 6800 µF (+5 V reservoir, before Q1); C18 10 V 330 µF (+5 V output); C1 50 V 1 µF (at the base of Q7 in the +5 V regulator); C10 25 V 4700 µF (input of IC1 AN7812R); C7 16 V 330 µF (+12 V output); C6 25 V 1000 µF (input of IC2 AN7912T); C12 16 V 100 µF (−12 V output); C14 16 V 100 µF (−5 V output); C38 50 V 3.3 µF (with R38, delays the rise of +5 V and +12 V); C2 and C16 0.1 µF. The text on page 18 calls the +5 V smoothing capacitor C7. Power source board: C101 and C102 0.1 µF in the line filter. See Panasonic CF-2700 Service Manual.
- ↑ 3.0 3.1 File:Panasonic CF-2700 main board, German model.jpg, photograph of a German CF-2700 main board uploaded to the MSX Resource Center wiki by Mars2000you on 7 April 2020. Read from it: board marking DFUP0007ZBJ-1; a 4700 µF 16 V capacitor at the bottom left beside D15; a silkscreen position C84 below it; the supply section at the top left with diodes D7 and D8 and three large reservoir capacitors; two DRAMs (HM50464P-15) at IC11 and IC12 and two TMS4416 video RAMs at IC49 and IC50, where the manual's board has eight of each.
- ↑ 4.0 4.1 4.2 Recap recommendations, June 2018—link(accessed 2026-10-21) RetroTechie, 23 June 2018: in an MSX, 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; 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; buy from established distributors. Wlcracks: use Rubycon, Chemi-Con, Nichicon or Panasonic.
- ↑ 5.0 5.1 Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 7: "The Reset Circuit utilizes the charge of CR Circuit (C13 and R26)"; Q10 raises RESET when the capacitor reaches about 1.5 V, so RESET goes from low to high 60 ms after power-on. See Panasonic CF-2700 Service Manual.
- ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 9, Fig. 7 "VDP Peripheral Circuit Diagram": C52 "22µ/10V" at the supply of IC38 (TMS9929), C28 "220µ/16V" at the supply of the video RAM IC49 to IC56; printed page 11, Fig. 8 "PSG Peripheral Circuit": C55 "22µ/10V" at the supply of IC36 (AY-3-8910A). See Panasonic CF-2700 Service Manual.
- ↑ Matsushita, Service Manual: Personal Computer CF-2700 (IED84113035C2), printed page 41: slot pins 41 and 43 GND, 45 and 47 +5 V, 48 +12 V, 50 −12 V. Printed page 39, "Adjustment": VR1 for 4.97 to 5.03 V at pin 45 of CN7 against pin 41. See Panasonic CF-2700 Service Manual.
