Sharp MZ-40K General Maintenance
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The Sharp MZ-40K is a single board under an acrylic cover, powered by an AC adaptor. No Sharp service manual for it has been found, so Sharp's schematic diagram and SharpMZ's technical notes are the sources. Every MZ-40K was built from a kit by its first owner, so the board's soldering is that owner's work.[1][2][3]
Power adaptor
[edit | edit source]The MZ-40K needs an AC adaptor. The board rectifies the AC itself and also takes the raw AC to the processor as the time base for its clock, so SharpMZ warns that a DC supply cannot be used.[4]
| Version | Input | Output | Plug |
|---|---|---|---|
| European (SharpMZ) | 220/240 V AC, 50/60 Hz, 11 W | 10.5 V AC, up to 700 mA | 3.5 mm jack |
| Japanese (Japanese Wikipedia; Sharp schematic Z0001) | 100 V AC, 50/60 Hz | 11 V AC | Mini plug |
[4][3][1] If the original adaptor is lost, a replacement must be a transformer with an AC output of about 10.5 to 11 V that can supply 700 mA, on a 3.5 mm plug. A DC adaptor would not run the clock.[4][3]
Power supply on the board
[edit | edit source]- The power switch is part of the volume control.[3]
- The 1B4B1 bridge rectifier feeds C10 (1000 µF 16 V) and the TA78005P regulator, which sits on a radiator plate.[1][5]
- The supply gives 5 V unregulated for the LED display and 5 V regulated for the logic.[4]
With the adaptor connected and the switch on, the regulator's output should read 5 V.[4]
Cover and case
[edit | edit source]The case is an acrylic cover with a fitted base. The acrylic is brown, so the parts cannot be seen through it; museum examples have clear covers like those in Sharp's advertising.[3] SharpMZ gives the operating temperature as above 5 °C.[4]
Keypad, display and sound
[edit | edit source]- The 22 keys are type ML-3 switches, marked with hex values, note names and six functions (ADR, READ, WRITE, CLEAR, RUN, STOP).[4]
- The display is four GL-8P04 red 7-segment LEDs, 10 mm high, multiplexed by the processor's timer.[4]
- Sound comes from a single loudspeaker driven by an LM390 or LM388 amplifier (IC1), up to 400 mW, through C4 (470 µF).[4][1]
Jumpers and options
[edit | edit source]- The telephone charge rate is set by four soldered jumpers in a 1-2-4-8 code, giving 1 to 15 units.[2]
- Two option jumpers enable Option 1.[4]
- Option 1 (MZ-40K1) uses six 2.5 mm jacks for its sensors: three micro switches, a reed switch with magnet, a water-level sensor and a light sensor. Option 2 (MZ-40K2) is a 32-key organ keyboard on the Option 2 socket.[4][1]
Maintenance checklist
[edit | edit source]- Check the adaptor gives AC, not DC, at about 10.5 to 11 V.
- Inspect the solder joints, especially round the jack, the bridge, C10 and the regulator.
- Measure the regulated 5 V.
- Check the electrolytic capacitors listed in the Sharp MZ-40K Capacitor Replacement Guide.
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 Sharp Corporation, MZ-40K schematic diagram, reproduced at Diagram MZ-40K, SharpMZ—link(accessed 2026-10-21) Also hosted as File:Sharp MZ-40K schematic diagram.jpg. AC adaptor Z0001; power switch S65; bridge 1B4B1; C10 1000 µF 16 V; TA78005P regulator; +5 V unregulated and +5 V regulated outputs; AC to the clock input through R4, C11, D1, R5 and TR1; IC1 audio amplifier and speaker; crystal 3.579545 MHz; Option 1 sensor inputs JK1 to JK6; Option 2 socket.
- ↑ 2.0 2.1 The MZ-40K kit– SharpMZ and Richard Cornelius, SharpMZ—link(accessed 2026-10-21) Sold only as a kit, in Japan and Germany; the German manual has 68 pages, 23 of them assembly instructions; telephone charge rate set by permanently soldering four jumpers on the board; tune data is lost at power-off.
- ↑ 3.0 3.1 3.2 3.3 3.4 MZ-40K, Wikipedia (Japanese)—link(accessed 2026-10-21) Full kit; acrylic cover and fitted base form the case, the acrylic brown so the parts cannot be seen as in the advertisements, while museum examples are clear; AC adaptor with a mini plug, 11 V AC, rectified inside the unit, the mains frequency used as the clock source; the volume control has a switch and doubles as the main power switch.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 Technical data of the MZ-40K, SharpMZ—link(accessed 2026-10-21) Power from a maximum of 10.5 V AC, 50/60 Hz, giving 5 V DC unregulated for the LEDs, 5 V DC regulated and 5 V AC 50/60 Hz for the clock; the AC output of the power supply is used to display the time, so no DC power supply can be used; external power supply 220/240 V AC 50/60 Hz 11 W, output 10.5 V AC, 700 mA maximum, 3.5 mm jack plug; volume control with combined on-off switch; operating temperature above 5 °C.
- ↑ SharpMZ, photograph of the MZ-40K main board on Technical data of the MZ-40K, SharpMZ—link(accessed 2026-10-21) , hosted as File:Sharp MZ-40K main board (SharpMZ).jpg: board legends for the AC input jack, volume and on-off switch, rectifier, regulator TA78005P on its radiator plate, CPU X0036PAZZ, RAM 1 and RAM 2, crystal, LEDs, telephone jumpers and Option 1 and Option 2 positions.
