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Panasonic FS-A1 Capacitor Replacement Guide

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Panasonic FS-A1 main board DFUP0110ZAP3
FS-A1 main board DFUP0110ZAP3. The power supply electrolytics are at the upper left; the hybrid board's small electrolytics are on the green board in the middle

No Panasonic parts list for the Panasonic FS-A1 has been found. BABAX traced the main board (DFUP0110ZAP2) and its BX7396WB hybrid board and published a parts list with the value and rating of every capacitor, hosted here with the schematic as the Panasonic FS-A1 Schematic. The tables below come from that list. It is a community reading of one board, and the drawing notes that parts can differ between production lots, so check each capacitor against your own board before ordering.[1]

Main board electrolytics

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FS-A1 main board (DFUP0110ZAP2) electrolytics, from BABAX's parts list
Ref Value Voltage Position from the schematic
C1 4700 µF 16 V 9 V input from the adapter, before the +5 V regulator
C22 330 µF 6.3 V +5 V output of IC18 (M5236L) and Q3
C26 470 µF 35 V Input of IC16 (78L12, +12 V)
C17 220 µF 16 V Output of IC16 (+12 V)
C2 470 µF 35 V Input of IC17 (79L12, −12 V)
C27 220 µF 16 V Output of IC17 (−12 V)
C6 470 µF 16 V Elsewhere on the board
C12, C13, C18, C19 470 µF 10 V Elsewhere on the board
C60 470 µF 6.3 V Elsewhere on the board
C38, C52 1000 µF 6.3 V Elsewhere on the board
C4, C7, C32 100 µF 10 V Elsewhere on the board
C34 22 µF 10 V Elsewhere on the board
C55 22 µF 6.3 V Elsewhere on the board
C44 2.2 µF 50 V Elsewhere on the board

[1]

Hybrid board (BX7396WB) electrolytics

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FS-A1 hybrid board electrolytics, from BABAX's parts list
Ref Value Voltage
H_C1, H_C2, H_C3, H_C6, H_C7, H_C12, H_C13, H_C14, H_C27 1 µF 50 V
H_C4, H_C28 2.2 µF 50 V
H_C23, H_C26 4.7 µF 35 V
H_C31 100 µF 10 V

[1] The hybrid board in the FS-A1 is not the HIC-1 board (Mitsumi EMC-NX0039) whose surface-mount capacitors leak in the Panasonic FS-A1MK2 and Panasonic FS-A1F. The MSX Resource Center says the FS-A1's daughterboard capacitors do not need replacing as a precaution.[2][3] The photograph above shows its capacitors as small radial parts on the green board.

A capacitor kit for the FS-A1 does not fit the Panasonic FS-A1MK2, whose board has different values in the same designators. One FS-A1MK2 recapped with an FS-A1 kit blew C1 at its first power-on.[4]

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, replacing one at a time.[5] On the FS-A1 that means:

  1. C1, C22, C26, C17, C2 and C27 in the power circuit.
  2. The hybrid board's capacitors, if the picture or sound is poor.
  3. The rest, only if they show leakage or bulging, or a rail is noisy.

The FS-AA51 adapter has its own smoothing capacitor for the 9 V output, which niga2 notes is now old; it is part of the same supply.[6] Its value has not been published; read it from the part.

Recording your own board

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  1. Photograph the main board and the hybrid board, then each electrolytic close up so the printing can be read.
  2. Compare every capacitor with the tables above. Where the board differs, go by the board.
  3. Note the diameter and height of each part; the space round the power capacitors is limited by the shield.

Procedure

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  1. Unplug the adapter and take the cells out of the battery compartment.
  2. Replace one capacitor at a time, with the stripe on the same side as the original and the voltage rating the same or higher.[5]
  3. Clean any electrolyte from the board. The FS-A1 board is single-sided with jumper wires on the component side, so check that no jumper has been disturbed.[7]
  4. Reassemble and refit the cells.

After the recap

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Measure the rails at a cartridge slot with the machine running: +5 V on pins 45 and 47, +12 V on pin 48 and −12 V on pin 50, with pins 41 and 43 as ground.[8] Then check that DESKPAC or BASIC starts, that a cartridge runs in each slot, and that the picture and sound are clean. Remaining faults are covered in the Panasonic FS-A1 Troubleshooting Guide.

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References

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  1. ↑ 1.0 1.1 1.2 BABAX, Panasonic MSX2 FS-A1 board (PWB) Rev.02 schematic, PWB DFUP0110ZAP2, revision 01a, 14 April 2015, parts list pages 3 to 7 ("CHEMICAL CAPACITOR" entries, all 85 °C) and schematic page 1 (power circuit). Hosted as File:Panasonic FS-A1 schematic and parts list (BABAX, Rev 01a).pdf; see Panasonic FS-A1 Schematic. Main board: C1 4700 µF 16 V; C2 470 µF 35 V; C4 100 µF 10 V; C6 470 µF 16 V; C7 100 µF 10 V; C12 and C13 470 µF 10 V; C17 220 µF 16 V; C18 and C19 470 µF 10 V; C22 330 µF 6.3 V; C26 470 µF 35 V; C27 220 µF 16 V; C32 100 µF 10 V; C34 22 µF 10 V; C38 1000 µF 6.3 V; C44 2.2 µF 50 V; C52 1000 µF 6.3 V; C55 22 µF 6.3 V; C60 470 µF 6.3 V. Hybrid IC BX7396WB: H_C1 to H_C3, H_C6, H_C7, H_C12 to H_C14 and H_C27 1 µF 50 V; H_C4 and H_C28 2.2 µF 50 V; H_C23 and H_C26 4.7 µF 35 V; H_C31 100 µF 10 V. Power circuit positions: C1 on the 9 V input; C22 on the +5 V output of IC18 and Q3; C26 at the input and C17 at the output of IC16 (78L12, +12 V); C2 at the input and C27 at the output of IC17 (79L12, −12 V). The note on the parts list warns that part numbers may differ between production lots.
  2. ↑ Panasonic FS-A1, MSX Resource Center wiki, 7 March 2026—link(accessed 2026-10-21) "The systemboard has a daughterboard, but this is not a HIC-1 board and the capacitors on it do not need proactive replacement."
  3. ↑ Urgent alert to MSX2/2+ owners: suicide capacitors on HIC-1 daughterboard, July 2015 onwards—link(accessed 2026-10-21) sd_snatcher, 19 July 2015, lists the FS-A1 among machines with the HIC-1 board; gdx replies the same day that the FS-A1's daughterboard is a different part.
  4. ↑ Capacitor List for Panasonic FS-A1 MKII, March 2021—link(accessed 2026-10-21) akugou: an FS-A1mkII recapped by someone else with Console5's kit for the FS-A1 blew C1 at power-on; the C1 on his mkII board was 1000 µF 35 V, against 4700 µF 16 V on the FS-A1. sdsnatcher73: the FS-A1 and FS-A1mk2 are not the same.
  5. ↑ 5.0 5.1 Recap recommendations, June 2018—link(accessed 2026-10-21) Reply by RetroTechie, 23 June 2018: supply bypassing electrolytics round an MSX board can often be removed without the machine stopping; audio and video electrolytics show their condition in the output; main power supply electrolytics are worth replacing whatever their condition; use the parts list and compare it with the board, and replace one capacitor at a time.
  6. ↑ 初代 FS-A1の改造– niga2—link(accessed 2026-10-21) In Japanese. Inside the FS-AA51 the DC 9 V is rectified and smoothed by a capacitor whose age is a concern; the Panasonic adapter is closed with ordinary screws.
  7. ↑ FS-A1Mk2のメモリ512kB増設– niga2—link(accessed 2026-10-21) In Japanese. The original FS-A1 board is single-sided with many jumper wires on the component side.
  8. ↑ MSX Cartridge slot, MSX Resource Center wiki, 6 July 2026—link(accessed 2026-10-21) Pins 41 and 43 GND, 45 and 47 +5 V, 48 +12 V, 50 −12 V.



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