Sanyo MPC-25FD Capacitor Replacement Guide
No capacitor list, parts list or circuit diagram for the Sanyo MPC-25FD has been published, and no service manual for any Sanyo MSX is held in the MSX Archive's collection.[1] The positions below are read from photographs of an opened machine. Read the values from your own board.
What is known
[edit | edit source]The supply is a separate board, marked UF0673, at the left of the case. These electrolytic capacitors can be identified on it from a photograph:[2]
| Ref | Position | Notes |
|---|---|---|
| C005 | Primary side, near the mains input | Largest on the board; sleeve marked +85 °C |
| C007, C008 | Primary side, below C005 | Small, side by side |
| C011, C012 | Primary side, beside the transistors | Small |
| C050 | Secondary side | Medium |
| C055 | Secondary side, beside the 100 µH choke | Large |
| C056 | Secondary side, lower left | Medium |
| Two unmarked | Secondary side, beside C055 and at the lower left | Large and medium; designators hidden in the photograph |
There are further electrolytics on the upper and lower boards.[3] No Sanyo values for any position are known.
The Philips NMS 8250, which Sanyo also built, has its supply documented in Philips's service manual, but that is a different board, 41 674 B12, with capacitors numbered C1050 to C1054.[4] Its values do not apply to the MPC-25FD.
Which to replace first
[edit | edit source]General 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 on the logic boards unless there is a reason.[5] On the MPC-25FD that means:
- The secondary-side capacitors of the supply board: C050, C055, C056 and the two unmarked ones.
- The primary-side capacitors, C005 and the small ones near it. C005 runs at rectified mains voltage, so copy its voltage rating exactly or go higher.
- Any capacitor near the video outputs, if the picture is poor.
While the case is open, deal with the Cadnica backup cell as described in the Sanyo MPC-25FD General Maintenance guide. Nickel-cadmium cells have a potassium hydroxide electrolyte, which corrodes the board if the cell leaks.[6]
Recording the board
[edit | edit source]- Unplug the machine, open the case and let C005 discharge; measure across it.
- Photograph the supply board and both logic boards from above, then each electrolytic close up.
- For each capacitor, write down the designator, capacitance, voltage, temperature rating, diameter and height, and which side the stripe faces.
- Order replacements of the same capacitance and at least the same voltage. Use 105 °C parts on the supply board.
| Ref | Board | Value | Voltage | Temperature | Diameter × height | Notes |
|---|---|---|---|---|---|---|
| C005 | Supply | +85 °C (marked) | ||||
| C055 | Supply | |||||
Procedure
[edit | edit source]Warning: the supply board's primary side carries mains voltage, and C005 can stay charged after the plug is pulled.
- Photograph and unplug the harness from the supply board, and lift the board out.
- Replace one capacitor at a time, stripe on the same side as the original.[5]
- Clean off any electrolyte and check the tracks. See Capacitor Failure Symptoms.
- Refit the board and the harness.
After the recap
[edit | edit source]Switch on with no cartridge fitted and measure the rails at the cartridge slot: +5 V on pins 45 and 47, +12 V on 48 and −12 V on 50, against pin 41 or 43.[7] Then check that the machine starts, that the drive reads a disk and that the picture is clean. Remaining faults are covered in the Sanyo MPC-25FD Troubleshooting Guide.
Related pages
[edit | edit source]- Sanyo MPC-25FD
- Sanyo MPC-25FD General Maintenance
- Sanyo MPC-25FD Troubleshooting Guide
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ Index of /pub/msx/docs/service_manuals, MSX Archive—link(accessed 2026-10-21) Directory of MSX service manuals; none for any Sanyo machine.
- ↑ File:Sanyo MPC-25FD power supply board.jpg, cropped from a photograph uploaded to the MSX Resource Center wiki by Mars2000you as "Sabyo MPC-25FD mainboard" (the MSX Resource Center's MPC-25FS page uses the same photograph). Read from it: board UF0673; a 6 W 2.2 Ω wirewound resistor at the mains input; reservoir capacitor C005, its sleeve marked +85 °C; small electrolytics C007 and C008 side by side, and C011 and C012; a TDK transformer marked AE0081; two opto-couplers beside C020 and IC052; on the secondary side C050, C055, C056 and two further large electrolytics whose designators are hidden; a 100 µH choke; test points TP002 and TP003. The values printed on the capacitors cannot be read at the resolution of the photograph.
- ↑ File:Sanyo MPC-25FD inside, upper board.jpg and File:Sanyo MPC-25FD main board.jpg, photographs uploaded to the MSX Resource Center wiki by Mars2000you: radial electrolytics on both boards, and a Sanyo Cadnica backup cell soldered to the upper board.
- ↑ Philips NMS 8250 Capacitor Replacement Guide, citing Philips's Service Manual NMS8250/NMS8255 (PDF page 32): power supply board layout 41 674 B12 with C1050 to C1054.
- ↑ 5.0 5.1 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; replace one capacitor at a time. Other replies recommend Rubycon, Chemi-Con, Nichicon or Panasonic parts from established distributors.
- ↑ ニッケル・カドミウム蓄電池, Japanese Wikipedia—link(accessed 2026-10-21) In Japanese. Nickel-cadmium cells use an aqueous potassium hydroxide electrolyte; "Cadnica" is Sanyo Electric's registered trade mark for them.
- ↑ MSX Cartridge slot, MSX Resource Center wiki—link(accessed 2026-10-21) Standard MSX cartridge slot pinout: pins 41 and 43 GND, 45 and 47 +5 V, 48 +12 V, 50 −12 V.
