Sony HB-F1 Troubleshooting Guide
No service manual or fault-finding guide for the Sony HB-F1 has been found. The checks below come from the machine's rating label, the MSX Resource Center's notes on its adapter, and one repair thread on that site's forum in which an arcade board repairer and several MSX owners worked through a dead HB-F1.[1][2][3] That thread ended without a confirmed cure, so treat its findings as a list of things to check. Routine work is in the Sony HB-F1 General Maintenance guide.
Start with the supply
[edit | edit source]The HB-F1 takes DC 9 V at 1.2 A and AC 18 V at 170 mA from its AC-HB3 adapter.[1][2] Measure both outputs of the adapter first. On the main board, two +5 V regulators and a 12 V regulator produce the rails.[3] Measure them at a cartridge slot against pin 41:[4]
| Pin | Rail |
|---|---|
| 45 or 47 | +5 V |
| 48 | +12 V |
| 50 | −12 V |
Things that are not faults
[edit | edit source]- The HB-F1 makes no sound at start-up unless a game cartridge is fitted.[3]
- It starts into the Personal Databank program. Hold DEL during start-up to reach BASIC.[5]
- It will start with the keyboard unplugged, but it then sits in the built-in program.[3]
Symptoms
[edit | edit source]| Symptom | Check first | Notes |
|---|---|---|
| No power lamp | The adapter and its plug | The AC-HB3 and Panasonic's FS-AA51 are interchangeable; the AC-HB1 and AC-HB2P have a different plug and voltages and cannot be used.[2] |
| Power lamp on, black screen | The rails, then the clock chip, then the ROM and RAM | On one machine the main ROM, IC14, a Fujitsu MB831124 128K × 8 mask ROM, was dead. A 64 KB EPROM such as a W27C512 holding only the main ROM and sub-ROM can replace it. A RAM cartridge in a slot lets the machine start past faulty internal RAM, and an MSX1 BIOS in place of the main ROM tests the CPU, RAM and slot selection without the clock chip or sub-ROM.[3] |
| A diagnostic ROM reports error 711 (clock) | The AA cells and the clock section of the S1985 | Bad values in the clock chip can stop the machine starting; replace or remove the AA cells. Check the /ALM signal at pin 87 of the S1985 and the clock crystal pins.[3] |
| Screen colours change slowly and the machine takes minutes to start | The speed controller slider | With the slider unplugged the machine starts very slowly; a jumper across its connector gives normal speed for testing.[3] |
| Clock loses time or resets | The AA cells | Check them and their holder for leakage.[3][6] |
| Picture flickers or sound crackles when a lead is moved | The connector's solder joints | Reflow the joints on the DIN, RCA and joystick connectors.[6] |
| Poor picture or sound with good rails | Electrolytics in the audio and video area | Faulty capacitors there show in the output.[7] See the Sony HB-F1 Capacitor Replacement Guide. |
The HB-F1 does not have the HIC-1 module of the HB-F1XD family, so the HIC-1 faults on those machines do not apply. Its EX-1 daughterboard carries only a ceramic capacitor.[3][8]
Related pages
[edit | edit source]- Sony HB-F1
- Sony HB-F1 General Maintenance
- Sony HB-F1 Capacitor Replacement Guide
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.0 1.1 Rating label of the HB-F1, photographed for the MSX Resource Center wiki (File:Sony HB-F1 rating label.jpg, uploaded by Mars2000you, 3 January 2023): "MODEL HB-F1 HOME COMPUTER", input "DC9V 1.2A AC18V～170mA", ソニー株式会社, Made in Japan.
- ↑ 2.0 2.1 2.2 Sony AC-HB3, MSX Resource Center wiki—link(accessed 2026-10-21) The external power supply supplied with the Japanese HB-F1 and HB-F1II: input AC 100 V, 50/60 Hz, 23 VA; outputs DC 9 V 1.2 A and AC 18 V 170 mA; connector sometimes called Mini-IEC; same specification, connector and pin-out as the Panasonic FS-AA51, so the two are interchangeable; the Sony AC-HB1 series and AC-HB2P use a different connector and voltages and cannot be substituted. The page shows a circuit diagram of the adapter.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Trying to repair a Sony HB-F1 (MSX 2), December 2017—link(accessed 2026-10-21) Apocalypse, a console and arcade board repairer, on an HB-F1 with a black screen and the power lamp lit: the main ROM IC14, a Fujitsu MB831124 128K × 8 mask ROM in a 28-pin package, was dead; rails were correct from two +5 V regulators and a 12 V regulator; clock present, reset not stuck, activity on the buses; the EX-1 daughterboard carries only one ceramic capacitor; a Philips diagnostic ROM reported error 711 (RTC); the clock chip is inside the S1985; he fitted sockets and new Z80 and 41464 RAM chips without curing it, and the thread ends unresolved. Replies: the machine has a single mask ROM; gdx suggests a 64 KB EPROM such as a W27C512 holding only the main ROM and sub-ROM; sd_snatcher suggests a RAM cartridge in a slot to boot past faulty internal RAM, and an MSX1 BIOS to test the CPU, RAM and slot selection; with the speed controller slider disconnected the machine boots very slowly, and a jumper across its connector restores normal speed; meits: the machine makes no sound at start-up unless a game cartridge is fitted, and starts without the keyboard but then sits in the built-in software; Jipe first suggested the HIC-1, then corrected himself that the HB-F1 uses a different board; gdx: the AA batteries are not needed to start, but bad values in the clock chip can stop it starting, so replace weak batteries or take them out; gdx: check /ALM on pin 87 of the S1985 and the clock crystal pins.
- ↑ MSX Cartridge slot, MSX Resource Center wiki—link(accessed 2026-10-21) Pin-out of the MSX cartridge slot: pins 41 and 43 ground, 45 and 47 +5 V, 48 +12 V, 50 −12 V, 49 sound input, 42 CPU clock 3.579545 MHz; +5 V must supply up to 300 mA per slot and ±12 V up to 50 mA for all slots.
- ↑ Sony HB-F1, MSX Resource Center wiki—link(accessed 2026-10-21) Community specification page: MSX2, 1986, Japan, ¥32,800; black, or black and red; 64 KB RAM in slot 3-3, 128 KB VRAM, Yamaha V9938, PSG, Yamaha S1985 MSX-Engine; pause button and speed controller slider, no reset button; supplied with the AC-HB3 external power adapter; replaced at the end of 1987 by the HB-F1II; built-in Personal Databank software, bypassed by holding DEL during start-up; two cartridge slots, one on top and one at the back; RF, composite video and audio, RGB (8-pin DIN), cassette, printer and two general-purpose ports. Fixes and repair: the built-in software can be disabled permanently by cutting a bridge near the MB64H444.
- ↑ 6.0 6.1 Vulnerable MSX hardware, MSX Resource Center wiki—link(accessed 2026-10-21) All MSX2 and later machines have a battery for the real-time clock; drained batteries, alkaline ones especially, leak; take removable batteries out before storage; lithium AA cells as an alternative. Lists the Sony HB-75P ("not as serious, as the problem caps are on separate small PCBs"), HB-F1II, HB-F1XD, HB-F1XDJ ("the ELNA caps are risky, the Nichicon ones are ok"), HB-F1XDmk2 and HB-F1XV among models with leaky capacitors. Fractured solder joints on DIN, RCA and DE-9 connectors cause flickering video and crackling sound; reflow them.
- ↑ 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; 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 to avoid mixing up values or polarity; buy from established distributors. Wlcracks recommends Rubycon, Chemi-Con, Nichicon or Panasonic parts and checking the board for leakage and smell.
- ↑ MSX2以降用ハイブリッドIC「EMC-NX0039」の回路図, 19 May 2020—link(accessed 2026-10-21) In Japanese, with the author's redrawn schematic as a PDF. Mitsumi hybrid IC EMC-NX0039 (HIC-1): RGB to NTSC encoder (CXA1145M), sound output amplifier mixing the PSG, the 1-bit sound port and the audio from slots 1 and 2, reset and pause muting, cassette interface amplifiers and relay control. Used in the Sony HB-F1II, HB-F1XD, HB-F1XDmk2, HB-F1XDJ and HB-F1XV and the Panasonic FS-A1mkII and FS-A1F. Sony part number 1-464-877-11. Two 10 µF and one 100 µF electrolytics, all known to leak; the author replaced them with tantalums and advises fused types because tantalums fail short. C26 is a through-hole part on early modules and an SMD part on later ones. R32 and R33 are 220 kΩ on Sony modules and 150 kΩ on Panasonic ones.
