Panasonic FS-A1ST Capacitor Replacement Guide
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The Panasonic FS-A1ST main board has 46 aluminium electrolytic capacitors. Panasonic's Technical Guide lists them by position and part number on pages 39 and 40 of its parts list.[1] The parts list does not print values; the values below are decoded from the Panasonic part numbers, whose voltage codes are 0J 6.3 V, 1A 10 V, 1C 16 V, 1V 35 V and 1H 50 V, with the capacitance in µF as two figures and a number of zeros.[2] The supply capacitors' values are also printed on the circuit diagram on page 22, and they agree.[3]
Before you start
[edit | edit source]Whether these machines need recapping at all is open to debate. In a 2025 thread meits said the turbo R machines are not known for bad capacitors, and that new capacitors are not automatically better than the originals.[4] A failed electrolytic can still take the supply down: in another 2025 repair the fault was a shorted 6.3 V 1000 µF capacitor on the YM2413's supply.[5]
When choosing replacements, sdsnatcher73 advises staying close to the original voltage rating and never going lower.[5] For C50, Jipe said a 35 V 15000 µF part is a suitable replacement for the original 25 V 12000 µF.[6]
Unplug the machine and remove the main board as described in the maintenance guide.[7]
Main board electrolytics
[edit | edit source]| Positions | Qty | Value | Voltage | Panasonic part | Notes |
|---|---|---|---|---|---|
| C50 | 1 | 12000 µF | 25 V | ECOS1EP123DA | Main reservoir after D2 and D3; feeds the +5 V converter and IC11 |
| C10 | 1 | 4700 µF | 10 V | ECEA1AU472 | +5 V converter output, after L6 |
| C59 | 1 | 470 µF | 35 V | ECEA1VU471 | −12 V reservoir, before IC13 |
| C51, C42 | 2 | 100 µF | 16 V | ECEA1CU101 | +12 V, either side of L9 |
| C60, C41 | 2 | 100 µF | 16 V | ECEA1CU101 | −12 V, either side of L10 |
| C27, C35, C162, C163, C164, C165 | 6 | 100 µF | 16 V | ECEA1CU101 | |
| C67 | 1 | 1000 µF | 6.3 V | ECEA0JU102 | The only 1000 µF 6.3 V part in the list |
| C1, C2, C7, C8, C9, C38, C52, C61, C66, C68, C70, C71 | 12 | 470 µF | 6.3 V | ECEA0JU471 | |
| C23, C44 | 2 | 100 µF | 6.3 V | ECEA0JU101 | |
| C36 | 1 | 47 µF | 16 V | ECEA1CU470 | |
| C21 | 1 | 22 µF | 6.3 V | ECEA0JU220 | |
| C22, C26, C28, C37 | 4 | 10 µF | 16 V | ECEA1CU100 | |
| C43, C54, C55, C58, C63, C64 | 6 | 2.2 µF | 50 V | ECEA1HU2R2 | |
| C20, C34, C47, C62 | 4 | 1 µF | 50 V | ECEA1HU010 | |
| C19, C40 | 2 | 1 µF | 50 V | ECEA1HN010 | Bi-polar (SU series); replace with bi-polar parts |
[1][2][3][8] The quantities add up to 46. The notes cover the positions shown on the power supply diagram; for the rest, see the main system circuit diagrams on pages 19 to 21 and the board layouts on pages 17, 18, 23 and 24.[3][9]
Drive
[edit | edit source]The drive's own electrolytics are not in the Technical Guide's parts list. For the drive in an FS-A1GT, Jipe read these values from an old drive he had replaced: C17 220 µF 6.3 V, C14 47 µF 6.3 V and C12 22 µF 16 V. gdx said a Japanese page listing the capacitors of both the FS-A1ST and the FS-A1GT, drive included, agreed with Jipe; that page no longer loads.[4] Check the markings on your own drive before removing the old parts.
Other capacitors
[edit | edit source]The audio modification in the maintenance guide changes four small surface-mount capacitors (C48, C49, C57, C159), which are not electrolytics.[10]
References
[edit | edit source]- ↑ 1.0 1.1 Technical Guide: FS-A1ST, printed pages 39 and 40, electrical parts list, aluminium electrolytic capacitors: C1, C2, C7, C8, C9, C38, C52, C61, C66, C68, C70, C71 ECEA0JU471; C10 ECEA1AU472; C19, C40 ECEA1HN010; C20, C34, C47, C62 ECEA1HU010; C21 ECEA0JU220; C22, C26, C28, C37 ECEA1CU100; C23, C44 ECEA0JU101; C27, C35, C41, C42, C51, C60, C162, C163, C164, C165 ECEA1CU101; C36 ECEA1CU470; C43, C54, C55, C58, C63, C64 ECEA1HU2R2; C50 ECOS1EP123DA (25 V, 12000 µF); C59 ECEA1VU471; C67 ECEA0JU102. Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ 2.0 2.1 Aluminum Electrolytic Capacitors, radial lead type, AM series (engineering specification), Panasonic, via alldatasheet—link(accessed 2026-10-21) Part number explanation: rated voltage codes 0J 6.3 V, 1A 10 V, 1C 16 V, 1E 25 V, 1V 35 V, 1H 50 V, 1J 63 V, 2A 100 V; capacitance code in µF, the first two figures significant and the third the number of zeros, R marking the decimal point, so 1 µF is 010.
- ↑ 3.0 3.1 3.2 Technical Guide: FS-A1ST, printed page 22: circuit diagram of the main board power section, LED board and switch board. AC 100 V through the double-pole power switch to the transformer. The secondary reaches the board at CN1: pin 1 is the centre tap (0 V), pins 2 and 3 the two ends, all through choke block L5. D2 and D3 charge C50 (25 V, 12000 µF), which feeds both the DC/DC converter and the +12 V regulator. DC/DC converter IC14 (MC34063) with Q1 (2SA1598), R36 (0.2 Ω, 1/2 W), R37 (100 Ω, 2 W), D8, L6 (220 µH), C10 (10 V, 4700 µF) and feedback resistors R96 (3.09 kΩ, 1 %) and R182 (1 kΩ, 1 %); L2 (20 µH) to the +5 V line, with zener D9, R217 (1 kΩ) and a thyristor from +5 V to ground. IC11 (C24M12HF) for +12 V with C51 and C42 (16 V, 100 µF) and L9 (220 µH). D4 and D5 charge C59 (35 V, 470 µF) for IC13 (AN7912T), −12 V, with C60 and C41 (16 V, 100 µF) and L10 (220 µH). D7 and D6 from the +12 V and −12 V lines to ground. DC voltages printed on the diagram include Q1 emitter 20.4 V, base 20.3 V, collector 5.2 V; IC14 pins 6 and 7 20.4 V, pin 5 1.2 V; IC11 input 20.5 V. Hosted as File:Panasonic FS-A1ST Technical Guide.pdf. The power section is reproduced as File:Panasonic FS-A1ST power supply circuit (Technical Guide).png.
- ↑ 4.0 4.1 FSA1GT EME213MU capacitor values., March 2025—link(accessed 2026-10-21) The owner of an FS-A1GT asked for the values of the three electrolytics on its drive. meits: those machines are not known for bad capacitors, and new capacitors are not automatically better. Jipe, from an old drive he had replaced: C17 220 µF 6.3 V, C14 47 µF 6.3 V, C12 22 µF 16 V. gdx: a Japanese page listing all capacitors for the FS-A1ST and FS-A1GT, drive included, confirmed Jipe's values (that page, www7b.biglobe.ne.jp/~leftyserve/zatsudan.htm, returned "404 Not Found" on 21 October 2026).
- ↑ 5.0 5.1 Turbo R ST not powering up (no 5+V either), October and November 2025—link(accessed 2026-10-21) alali.ahmed.t traced a short circuit to a failed 6.3 V 1000 µF capacitor connected to the YM2413, replaced it and recapped the board, but still had no +5 V. Jipe: check for about 15 V AC between CN1 pins 1 and 2 and between pins 1 and 3, and about 20 V DC across C50, measuring everything from the negative of C50; test diodes with one leg unsoldered (about 0.5 V one way); check that L5 is not open. The owner measured 18.7 V from pin 1 to pins 2 and 3 and 37.7 V between pins 2 and 3. kamiboy and sdsnatcher73 on replacement capacitor ratings (sdsnatcher73: stay close to the original voltage, never lower). Wierzbowsky: check the voltages given in the Technical Guide, then D2 and D3, the zener D9, D1 and D7, Q1 and then the DC/DC converter. The owner later reported the machine working after replacing several parts, including a faulty voltage regulator.
- ↑ New Problem Turbo R A1ST Smoked :o, August 2007—link(accessed 2026-10-21) CrazyBoss: on an FS-A1ST whose transformer had long before been replaced with a 220 V one, the large 25 V 12000 µF capacitor next to the supply became very hot and then smoked; he measured 21 V from the centre pin to each outer pin of the transformer, 42 V across the outer pins. Jipe: a 35 V 15000 µF part is fine as a replacement; the capacitor filters the supply before the regulators; he had fitted 220 V transformers with two 15 V windings to five turbo R machines without trouble.
- ↑ Technical Guide: FS-A1ST, printed pages 10 and 11, disassembly. Upper cabinet: five screws (A) on the underside, then connectors CN12 and CN14. Keyboard: three screws (B), slide it to the left while lifting, unplug the flexible cables from CN10 and CN11. Keyboard flex pattern: 18 screws on the back of the keyboard; keep dust out. Drive: four screws (C), unplug CN19 and the flat cable from CN13. Main board: with the upper cabinet, keyboard and drive removed, two screws (D) on the underside, two screws (E), five (F) and three (G); unplug CN1 and CN17. LED board: three claws (H). Operation panel: claws (I). Switch board: two screws (J). Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ Panasonic ECEA1HN010U Cap, 1µF, 50V, 20%, Farnell—link(accessed 2026-10-21) Distributor listing, order code 9696601: product range SU (bi-polar) series, radial leaded, 5 mm diameter, 11 mm high, 2 mm lead spacing, 85 °C.
- ↑ Technical Guide: FS-A1ST, printed page 2, contents. Hosted as File:Panasonic FS-A1ST Technical Guide.pdf.
- ↑ MSX hardware fixes and enhancements—link(accessed 2026-10-21) Section 2.2, Panasonic MSX turbo R audio fix: slot sound too loud, OPLL too quiet, OPLL and output low-pass filters too strong, output level too weak. For the FS-A1ST: C48 and C49 1.8 nF, R24 22 kΩ, R23 15 kΩ, C57 180 pF, C159 150 pF; all 0805 SMD; capacitors polyphenylene sulphide film or C0G ceramic.