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Sony HB-201 Troubleshooting Guide

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Sony HB-101P HB-201P power supply circuit (service manual)
The HB-101P/HB-201P power supply (Sony service manual, page 5-23). The HB-201P uses the AE version, for 220 V.

The European Sony HB-201 (HB-201P) shares its PU-34 main board, power supply and service manual with the HB-101P, so power faults are traced as in the Sony HB-101 Troubleshooting Guide.[1] The HB-201's own differences are in its memory and firmware chips and, on the Japanese model, its power board.

Warning: mains voltage is present inside the case. Unplug the mains cable before opening the machine.

Quick reference

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Symptoms, causes and actions
Symptom Probable cause Action
Dead Mains fuse F901 (T400mA), power switch, transformer thermal fuse, rectifiers HB-101 guide: No power
Indicator lit, no picture +5 V, video chip IC14, video RAM, PAL encoder, RF modulator No picture
Crashes or garbage when programs use more memory Main RAM IC22 or IC23 Memory
Personal Databank does not start, or software clashes with it Firmware in slot 0, IC8, jumper JW1 Personal Databank
Machine frozen with the PAUSE lamp lit PAUSE pressed Press PAUSE again

[1][2]

No picture

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The HB-201P's video chip is IC14, a TMS9129NL (+5 V pin 33, ground pin 12), and its 16 KB of video RAM is the pair of TMS4416-15NL left at IC20 and IC21 (+5 V pin 9, ground pin 18).[3] It drives the PAL encoder module and the RF modulator (MDG-UE3602).[4] Check +5 V at IC14, compare the RF output with the composite output on the 6-pin DIN socket, and check the clock at pin 6 of IC6 as described in the HB-101 guide.

The Japanese HB-201 has a TMS9118NL instead.[2] Niga, repairing the same chip in a Japanese HB-10, notes that the TMS9118 and the TMS9918 are not interchangeable, because they use different video RAM arrangements.[5]

Memory

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The HB-201P's 64 KB of main RAM is two µPD41254C-15 chips at IC22 and IC23 (+5 V pin 9, ground pin 18). The HB-101P has four TMS4416-15NL in those and two other positions, IC46 and IC47, which the parts table marks for the HB-101P only.[3] When replacing RAM on an HB-201P, fit 64K × 4 parts of the µPD41254 type, not the TMS4416 used on the HB-101P.

The RAM is in slot 3. The MSX Resource Center's slot map for the HB-201 shows no RAM in slot 0.[2]

Personal Databank

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On the HB-201 the Databank firmware sits in slot 0 at 8000h, beside the MSX-BASIC ROM.[2] Hold CTRL, SHIFT, CODE and GRAPH at switch-on to go straight to BASIC; CALL HITBIT returns to the Databank.[6] The Databank ROM is IC8, a TMM23128P-8712 on the HB-201P, fitted with jumper JW1 on its MASK side; the EP position is for an EPROM.[7]

Japanese HB-201 power board

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The Japanese HB-201 has its rectifiers and reservoir capacitors on a separate power board beside the 100 V transformer, with C905, C906, D901 and connector CN901 visible in a photograph of an opened machine.[8] CN901 is marked 8, GND, 8, 16 and GND, matching the 8 V centre-tapped and 16 V windings of the European supply.[8][9] Measure the AC at CN901 first when a Japanese HB-201 is dead.

Test points

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The full supply-pin table for the PU-34 board is in the HB-101 guide. The HB-201P differs only in its RAM (µPD41254C-15 at IC22 and IC23) and firmware ROM (TMM23128P-8712 at IC8), which use the same supply pins.[3]

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References

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  1. ↑ 1.0 1.1 Sony, HB-101P/201P Service Manual (File:Sony HB-101P HB-201P Service Manual.pdf). Hosted with a description at Sony HB-101P and HB-201P Service Manual.
  2. ↑ 2.0 2.1 2.2 2.3 Sony HB-201, MSX Resource Center wiki—link(accessed 2026-10-21) 64 KB in slot 3; firmware in slot 0 at 8000h; PAUSE halts the CPU; Personal Databank; TMS9118NL (HB-201) or TMS9129NL (HB-201P).
  3. ↑ 3.0 3.1 3.2 Sony, HB-101P/201P service manual (File:Sony HB-101P HB-201P Service Manual.pdf), IC supply table, page 5-16: IC14 TMS9129NL (+5 V 33, ground 12); IC20 and IC21 TMS4416-15NL; IC22 and IC23 µPD41254C-15 on the HB-201P; RAM supply pins +5 V 9, ground 18; IC8 TMM23128P-8712 on the HB-201P (+5 V 28, ground 14).
  4. ↑ Sony, HB-101P/201P service manual (File:Sony HB-101P HB-201P Service Manual.pdf), electrical parts list, page 7-7: PAL encoder 1-464-507-11; RF modulator 1-464-490-11 (MDG-UE3602) for the HB-101P and HB-201P AE.
  5. ↑ SONY HB-10の補修と改造– Niga, にがMSX—link(accessed 2026-10-21) The TMS9918 uses eight 16K × 1 DRAMs and the TMS9118 two 16K × 4 DRAMs; the chips are not interchangeable.
  6. ↑ Sony HB-201, MSX Resource Center wiki—link(accessed 2026-10-21) Firmware options, skipping it at boot, CALL HITBIT.
  7. ↑ Sony, HB-101P/201P service manual (File:Sony HB-101P HB-201P Service Manual.pdf), section 2-2, page 2-2.
  8. ↑ 8.0 8.1 File:Sony HB-201 (Japanese) inside.jpg, photograph uploaded to the MSX Resource Center wiki by Gdx on 24 May 2016: brown power board with C905, C906, D901 and CN901 marked 8, GND, 8, 16, GND; transformer 1-447-996-23, 100 V.
  9. ↑ Sony, HB-101P/201P service manual (File:Sony HB-101P HB-201P Service Manual.pdf), power supply schematic, page 5-23: CN13 on the PU-34 board carries AC 8 V, AC 8 V, GND, AC 16 V and GND from the transformer.


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