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Panasonic FS-A1MK2 Troubleshooting Guide

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Panasonic FS-A1MK2 HIC-1 board (EMC-NX0039)
The HIC-1 board in an FS-A1MK2. The Sony CXA1145 video encoder is at the lower right and the 100 µF surface-mount capacitor in the middle

No Panasonic fault-finding guide for the Panasonic FS-A1MK2 has been found. Most of the video and sound path runs through the HIC-1 board, and its leaking capacitors are the first suspect for a picture fault. The board's circuit is in the HIC-1 Hybrid Board Schematic. For the adapter, the backup cells and access to the board see the Panasonic FS-A1MK2 General Maintenance guide.

Things that are not faults

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  • The machine starts in the DESKPAC menu. Hold DEL during start-up, until it beeps, for BASIC.[1]
  • Holding GRAPH during start-up clears the clock's SRAM, so the date, time and stored settings are lost.[1]
  • With a Sunrise CF/IDE interface fitted, holding DEL also disables its partitions; redefine the key with IDKEYSET.COM or use the interface's BIOS 2.50b.[1]
  • A cartridge that needs ±12 V, such as an FM-PAC, fails on a machine converted to a 9 V-only adapter. The FS-A1MK2 itself runs without ±12 V.[2]

Fault table

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FS-A1MK2 faults and where to look
Symptom Check first Notes
Nothing at all The FS-AA51 adapter and its plug Rated DC 9 V 1.2 A and AC 18 V 170 mA; the adapter needs 100 V mains.[3][4]
Starts, but no picture, no colour, or a noisy or unstable picture The HIC-1 board: its three surface-mount electrolytics, corrosion round them, and the solder joints next to them The capacitors leak and the electrolyte corrodes the board.[5]
RGB picture good, composite or RF missing or only flickering in colour The composite path on the HIC-1 round pins 16 to 18 of the CXA1145, including its 22 µH inductor Reported on a Sony machine with the same board after a capacitor change; a bad joint on the inductor was the cause.[5]
Noise on the picture after a capacitor change that fades as the machine warms up The new capacitors and their joints on the HIC-1 Reported on a Sony HB-F1XD after fitting tantalum capacitors.[5]
FM-PAC or another cartridge needing ±12 V does not work The 18 V AC from the adapter, the 78L12 and 79L12 regulators, slot pins 48 and 50 On this model ±12 V feeds only the slots.[2]
Clock loses the time, settings lost The two AA backup cells and their contacts The label in the compartment gives R6P (SUM-3) cells.[6]

Power checks

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Measure 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.[7] If +5 V is missing, measure the adapter's 9 V output and then the regulator under the heatsink, which drops the 9 V to 5 V.[2] No circuit diagram of the FS-A1MK2's main board has been published, so trace the supply from the input socket on the board itself. The FS-A1's supply, documented in the Panasonic FS-A1 Schematic, is a different board and should not be used for part numbers on this one.[8]

No picture, sound working

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An FS-A1MK2 owner on the MSX Resource Center forum had sound but no picture on either composite or RGB. His repair, with the advice he was given, is the best-documented case for this model:[9]

  1. Rule out the cable first: try both composite and RGB. Both come from the HIC-1, so a fault on that board can stop both.[9]
  2. Measure the rails: +5 V at the slots, and +12 V at the regulator's output, measured on the DC range of the meter.[9][7]
  3. Inspect the HIC-1 for leaked electrolyte and eaten tracks, especially round the Sony CXA1145 encoder. Its pins 10 and 11 (sync in and sync out) were badly corroded on this machine.[9]
  4. With a meter, check the CXA1145: +5 V on pins 12 and 19, ground on pins 1 and 24, and the PAL/NTSC selector on pin 7. With a scope, look for the 3.58 MHz clock on pin 6, sync in on pin 10 and sync out on pin 11. Composite video comes out on pin 20.[9]
  5. If sync does not reach the CXA1145, its clamp holds every output at ground, so there is no picture on any output even with a working VDP. Repair the sync track before suspecting the VDP.[9]
  6. Once a picture appears, look for corruption. On this machine sprites were missing and two of the four video RAM chips ran hot; replacing all four (MB81464-12, or any 4464 DRAM of 120 ns or faster) finished the repair.[9]

After removing the old capacitors, neutralise the leaked electrolyte with water and a little vinegar, then wash with tap water and mild soap and let the board dry fully.[9]

Working on the HIC-1

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The HIC-1 runs from +5 V and takes its clock, RGB, sync, PSG and slot sound from the main board on its edge pins; its outputs are composite video, RGB, the mixed sound and the cassette signals.[10] With the schematic, check that each signal arrives on its pin before condemning the board. Its pads lift easily once they have been attacked by electrolyte; see the Panasonic FS-A1MK2 Capacitor Replacement Guide for the removal method.[11]

A capacitor fails at power-on

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Another owner's FS-A1MK2 popped a capacitor, C1 (1000 µF 35 V), the first time he powered it, and its HIC-1 was found badly corroded. The board had been recapped by someone using a capacitor kit meant for the FS-A1. Replies on the forum pointed out that the FS-A1 and FS-A1MK2 boards are different, warned that BABAX's FS-A1 schematic does not apply to the FS-A1MK2, and advised checking the supply rails, because an over-voltage on +5 V could have damaged other chips.[12][13] Fit capacitors to the values and ratings printed on the FS-A1MK2's own board, never from a list for another model.

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References

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  1. ↑ 1.0 1.1 1.2 Panasonic FS-A1mkII, MSX Resource Center wiki, 7 March 2026—link(accessed 2026-10-21) DESKPAC bypassed by holding DEL at start-up until a beep; GRAPH held at start-up initialises the clock's SRAM; with a Sunrise CF/IDE interface the DEL key also disables the partitions, so redefine it with IDKEYSET.COM or use the interface's BIOS 2.50b, which uses STOP; pause button; HIC-1 daughterboard with three SMD electrolytics that leak.
  2. ↑ 2.0 2.1 2.2 FS-A1mk2の単一電源化改造– niga2—link(accessed 2026-10-21) In Japanese. +5 V is stepped down from the DC 9 V; ±12 V comes from the AC 18 V through 78L12 and 79L12 regulators and is used only for the slots on the mk2; with a 9 V adapter alone, ROM games and PSG sound worked, but the FM-PAC needs ±12 V for its op-amp.
  3. ↑ Rating label of the FS-A1MK2: "電源入力 DC9V 1.2A AC18V 170mA". File:Panasonic FS-A1MK2 rating label.jpg.
  4. ↑ Panasonic FS-AA51, MSX Resource Center wiki, 17 September 2025—link(accessed 2026-10-21) Input AC 100 V 50/60 Hz 23 VA; output DC 9 V 1.2 A and AC 18 V 170 mA.
  5. ↑ 5.0 5.1 5.2 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): C10, C14 and C22 on the HIC-1 leak, C22 worst, with corrosive electrolyte. joseph0126 (1 August 2019, Sony HB-F1XD): after fitting tantalum replacements, noise on the left of the start-up screen that faded after about 10 minutes. dublevay (5 September 2020, Sony HB-F1XV): after replacing the capacitors, no composite or RF picture although RGB worked; traced to the 22 µH inductor on the HIC-1, whose joint was bad although it looked sound, near pins 16 to 18 of the CXA1145 where sync is added back for composite video; reflowing it cured the fault; the original 100 µF part was marked 6.3 V.
  6. ↑ Photograph of the FS-A1MK2 battery compartment on the MSX Resource Center wiki (File:Fsa1mk2d.jpg, uploaded by Mars2000you, 15 September 2020): label giving R6P (SUM-3), 2 cells.
  7. ↑ 7.0 7.1 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.
  8. ↑ Panasonic FS-A1, MSX Resource Center wiki, 7 March 2026—link(accessed 2026-10-21) "The main board is different from the board of the FS-A1mkII."
  9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 Panasonic FS-A1 Mk II - no video signal, May 2015 to January 2016—link(accessed 2026-10-21) sabre470's FS-A1mkII: sound but no picture; leaky capacitors on the daughterboard; after replacing them, traces were missing and the picture was still absent. l_oliveira: the daughterboard is the video and audio processing board; the leaked capacitors corroded the traces away; the encoder is a Sony CXA1145, whose RGB clamp needs the sync signal from the VDP, and without sync it clamps all its outputs to ground, so the VDP looks faulty when it is not; RGB also passes through the CXA1145; neutralise the leaked electrolyte with water and a little vinegar, then wash with tap water and mild soap. Wierzbowsky: check +5 V on CXA1145 pins 12 and 19, ground on pins 1 and 24, the PAL/NTSC selector on pin 7, 3.58 MHz on pin 6, C-sync in on pin 10 and out on pin 11; composite video is on pin 20; on a 7812, expect up to 22 V on the input and 12 V on the output, measured on the DC range. sd_snatcher: pins 10 and 11 of the CXA1145 were badly corroded. sabre470 (24 January 2016): after repairing eaten traces the picture returned, with sprites missing; two of the four video RAM chips (MB81464-12) ran hot; l_oliveira: the hot chips are bad and any 4464 DRAM of 120 ns or faster will do; with four new chips (30 January 2016) the machine worked fully.
  10. ↑ BABAX, Mitsumi Hybrid IC EMC-NX0039, revision 02. File:Mitsumi EMC-NX0039 HIC-1 schematic (BABAX, Rev 02).pdf; see HIC-1 Hybrid Board Schematic. Page 2: pin functions (3.58 MHz clock in, +5 V, RGB in, C-sync, PSG and sound inputs, cassette in and out, cassette remote, pause and power mute in; composite, RGB and sound mix out) and the board outline.
  11. ↑ FS-A1Fの改造 前編– niga2—link(accessed 2026-10-21) In Japanese. On the same HIC in an FS-A1F, solder joints near the capacitors had turned dull and gave off the smell of electrolyte when heated, showing that corrosion had spread widely; the pads lift very easily; one corroded pad was bypassed by soldering the capacitor directly to the IC's pin.
  12. ↑ Panasonic FS-A1 MKII problems, March 2021—link(accessed 2026-10-21) akugou (12 March 2021): no power lamp, then something popped; C1 (1000 µF 35 V) had failed and the HIC board was badly corroded. Wierzbowsky: the HIC board needs cleaning, repair and new capacitors; if another capacitor popped, check the power rails, since excess voltage on +5 V could have damaged many chips. gdx: capacitors other than those on the video board are unlikely to leak. sdsnatcher73: the FS-A1 schematic does not apply to the FS-A1mk2, which is totally different.
  13. ↑ Capacitor List for Panasonic FS-A1 MKII, March 2021—link(accessed 2026-10-21) akugou: the machine had been recapped by someone using Console5's kit for the FS-A1, and C1 blew at power-on. sdsnatcher73: the FS-A1 and FS-A1mk2 are not the same, only the mk2 has the HIC-1, and the other capacitors do not need preventive replacement. meits: the most accurate list is one made from the board itself.



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