Toshiba HX-22 Capacitor Replacement Guide
Electrolytic capacitors in the Toshiba HX-22. Toshiba's service manual and parts list for the HX-22 have not been found, and no list of capacitor values has been published, so read the value, voltage and polarity of each capacitor from your own boards before ordering parts.
Where the capacitors are
[edit | edit source]- The power supply board, a separate board next to the internal transformer. It holds the supply's capacitors and runs hot.[1][2]
- The video board at the top left of the case, which carries most of the electrolytics visible in a photograph of a Japanese HX-22.[3]
- The main board, which has only a few small electrolytics, near the joystick and cassette connectors and near the video chip.[3]
The European versions use a different gate array and may differ in layout.[4]
Values
[edit | edit source]No values for the HX-22 have been published. On the related Toshiba HX-10, the largest capacitors next to the +5 V regulator were 2200 µF 35 V and 4700 µF 16 V parts rated at only 85 °C; they are given in the Toshiba HX-10 Capacitor Replacement Guide for comparison, not as HX-22 values.[2]
Which to replace first
[edit | edit source]- The capacitors on the power supply board, which run hottest. Use 105 °C parts with at least the original voltage rating.[2]
- The video board capacitors, if the picture is poor.
- The main board capacitors, only if they show bulging or leakage or test faulty.
A full recap does not cure everything. One owner who recapped the whole machine and replaced the transistors, zeners and op-amp on the power board still had audible noise on the 5 V and 12 V rails, which needed a redesigned power board.[1]
Procedure
[edit | edit source]- Unplug the mains lead. The transformer is inside the case.[1]
- Photograph each board, then note each capacitor's value, voltage and polarity before removing it.
- Replace one capacitor at a time.
- While the power board is out, consider heat sinks for the regulators that lack them.[2]
After the recap
[edit | edit source]Measure +5 V, +12 V and −12 V, and −5 V at the 4116-type video RAMs.[3][5] Then check that BASIC starts, that the picture is clean and that there is no hum in the sound. Faults that remain are covered in the Toshiba HX-22 Troubleshooting Guide.
Related pages
[edit | edit source]- Toshiba HX-22
- Toshiba HX-22 General Maintenance
- Toshiba HX-22 Troubleshooting Guide
- Toshiba HX-10 Capacitor Replacement Guide
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.0 1.1 1.2 MSX Toshiba Pasopia IQ HX-20 HX-21 HX-22 Improved PSU, March 2022—link(accessed 2026-10-21) kinchan, 16 March 2022: a replacement power supply board with the same form factor as the original for the Pasopia IQ HX-2x series, reusing the original heat sinks and wiring, with low-noise LDO regulators, very low output ripple, and protection against over-voltage, overload, short circuit, reverse current and over-temperature. kinchan: after recapping the whole machine and replacing the transistors, zener diodes and op-amp on the original power board, the 5 V and 12 V rails still carried an audible wavy noise that reached the stereo audio; the original board has no protection, which exposes the transformer and the main board to failure.
- ↑ 2.0 2.1 2.2 2.3 My Toshiba HX-10 gets mighty hot!, December 2016—link(accessed 2026-10-21) sd_snatcher, 9 December 2016: Toshiba's MSX power supplies are among the worst on MSX machines, with heat sinks too small or missing, and run hot, worse with expansions and modern FPGA or CPLD cartridges; run Japanese models only at 100 V (never 110 V or 127 V, which can melt the transformer or burn the power supply board) and European models only at their rated voltage; avoid slot expanders without their own supply and very power-hungry cartridges; add heat sinks to the regulators that lack them and a 4 × 4 cm 12 V fan over the largest heat sink, the +5 V regulator (on the Japanese HX-22 he fixed the fan with one screw, turned 45 degrees); replace the NMOS Z80A with a CMOS Z80 of 10 MHz or less; MSX1 models can take a switching supply in place of the transformer and power board. In the HX-2x models there is room inside for a fan. gdx, December 2016 (on a Japanese HX-10): the two capacitors nearest the hot +5 V regulator were 2200 µF 35 V and 4700 µF 16 V parts rated at 85 °C; capacitors next to the hot regulators need a 105 °C rating where the temperature passes 80 °C.
- ↑ 3.0 3.1 3.2 File:Toshiba HX-22 main board.jpg, photograph of a Japanese HX-22 main board, uploaded to the MSX Resource Center wiki by Mars2000you on 13 December 2015. Read from it: the video board with its electrolytics at the top left, the cartridge slots at the top right, a Z80A (IC1), two Toshiba TMM23256P ROMs (IC2, IC3), the Toshiba TCX-1010 gate array, a GI AY-3-8910A, eight TMM416P-2 video RAMs (4116 type, IC37 to IC44), eight HM4864AP main RAMs, and a few small electrolytics on the main board near the joystick and cassette connectors. A label over the cartridge slots says, in Japanese, that cartridges must be changed only with the power switch off and the lamp out.
- ↑ Toshiba HX-22, MSX Resource Center wiki—link(accessed 2026-10-21) Community page for the HX-22 series: an improved HX-21 with a built-in RS-232C interface with an on/off switch; models HX-22 (Japan, QWERTY/JIS, RF, composite, stereo audio, RGB on an RP13A connector), HX-22CH (Switzerland), HX-22GB (UK) and HX-22I (Italy), the European ones with mono audio and RGB on SCART; released 16 October 1984 in Japan and 1985 in Europe; prices JP ¥89,800, UK £149.99, IT L. 599,000; 64 kB RAM in slot 3-0 on the HX-22, split between slots 0 and 3-0 on the HX-22I; 16 kB VRAM; TMS9928A or TMS9929A; AY-3-8910A; Toshiba TCX-1010 gate array in the HX-22, TCX-1012 in the HX-22I; a 32 kB firmware ROM (word processor); Sharp LH-0080A Z80A; two cartridge slots, one on top and one at the back; joystick ports and data recorder connector on the right side; connections: RF (with channel selector on the Japanese model), audio and composite video, RGB, RS-232C (DB-25) with on/off switch, data recorder, Centronics printer port, two joystick ports, two cartridge slots, AC power plug, ground terminal on European versions only. On the HX-22I the RAM split can make badly written software crash.
- ↑ Toshiba HX-10 -- unusual black screen issue!, March 2025—link(accessed 2026-10-21) On a Toshiba HX-10 with a black screen, the 4116 video RAMs had lost their −5 V supply and the logic saw 6.5 to 7 V after a zener in the supply section failed. sdsnatcher73: with correct supplies, check activity on the RAM and video RAM address and data lines with a logic probe or oscilloscope, the RAM and ROM chip selects, and the clock and reset of the VDP and CPU.