Sanyo MPC-200 Troubleshooting Guide
The Sanyo MPC-200 is the Spanish version of Sanyo's MPC-2, an MSX1 computer of 1985.[1] No service manual or circuit diagram for it has been published. The checks below come from Sanyo's Spanish operating instructions, photographs of an opened machine and the MSX standard.
Sanyo's table of problems
[edit | edit source]Page 13 of the operating instructions lists these symptoms and checks.[2]
| Symptom | Check |
|---|---|
| No picture | The MPC-200's power and plug; the television is plugged in; the lead between the MPC-200 and the television; brightness and contrast |
| The picture will not hold | Adjust the television's vertical and horizontal hold |
| Only random characters appear | Press RESET; switch off and start again |
| The computer stops during use | A momentary mains failure; interference from other equipment; an error in the program |
| The STOP key does not work | Press RESET; check the program |
| CSAVE or CLOAD does not work | Follow the procedure in chapter 4; clean the data recorder's head; adjust the recorder's volume |
| The joystick does not work | The connection between the MPC-200 and the joystick; the program |
Machine does not power up
[edit | edit source]Warning: the mains lead, the fuse and the transformer's primary carry mains voltage. Unplug the machine before opening it.
- Check the power switch at the rear and the power lamp on the top.[3]
- Check the mains lead and its two-pin plug for damage.[4]
- Open the case and check fuse F101, beside the transformer, which is marked T1A 250V.[5] If it has blown, look for a short before fitting another of the same rating.
- With the fuse good, measure the rails at a cartridge slot (below). If all of them are missing, trace back from the slot pins towards the transformer, checking the two large electrolytic capacitors and the part on the heatsink on the way.[5]
Supply rail checks
[edit | edit source]Measure with no cartridge fitted, against pin 41 or 43 of either slot.[6]
| Pin | Signal | If it is missing |
|---|---|---|
| 45, 47 | +5 V | Nothing runs. Check the fuse, the transformer and the parts between them and the slot. |
| 48 | +12 V | Trace the rail back from the slot pin. |
| 50 | −12 V | Trace the rail back from the slot pin. |
Sanyo published no tolerances for these rails.
Picture faults
[edit | edit source]- Go through Sanyo's table above first.[2]
- The video and RF outputs are PAL.[7] A monitor that cannot decode PAL shows the picture in black and white.[8]
- The Toshiba T6950 video chip does not support the undocumented "mirrored" screen modes of the TMS9918 family, so a few games and demos display incorrectly, and its colours differ slightly from the Texas Instruments chips.[9][1] Check a suspect program on another MSX before looking for a fault.
- Random characters on the screen: press the reset button, then switch off and on.[2]
Cartridge faults
[edit | edit source]- Switch off before inserting a cartridge, and insert it gently.[10] A cartridge inserted with the power on can damage both the cartridge and the computer, as the label beside the slots warns.[11]
- Try the cartridge in the other slot. A cartridge that runs in one slot but not the other points to the slot's contacts or its wiring to the board behind the connectors.[5]
- Clean the cartridge's contacts with isopropyl alcohol.
Cassette and joystick faults
[edit | edit source]- CSAVE and CLOAD: follow chapter 4 of the manual, clean the recorder's head and adjust its volume.[2] The interface records by FSK at 1200 or 2400 baud.[7]
- Joystick: check the plug in its port on the right-hand side, and try a program known to read the joystick.[2][3]
Related pages
[edit | edit source]- Sanyo MPC-200
- Sanyo MPC-200 General Maintenance
- Sanyo MPC-200 Capacitor Replacement Guide
- Sanyo MPC-200 Operating Instructions
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.0 1.1 Sanyo MPC-200, MSX Resource Center wiki—link(accessed 2026-10-21) Community specification page: the MPC-2 localised for Spain, 1985; internal power supply; Toshiba T6950 VDP, Toshiba T7775 MSX-Engine, AY-3-8910 PSG; two cartridge slots.
- ↑ 2.0 2.1 2.2 2.3 2.4 Sanyo, Ordenador personal MSX: Instrucciones para el funcionamiento (MPC-200), page 13, "Problemas". In Spanish. Hosted here as Sanyo MPC-200 Operating Instructions.
- ↑ 3.0 3.1 Sanyo, Instrucciones para el funcionamiento (MPC-200), page 1, "Nombres de los componentes": power indicator and reset button on the top; power switch, mains cable and outputs at the rear. See Sanyo MPC-200 Operating Instructions.
- ↑ File:Sanyo MPC-200 rear.jpg, photograph uploaded to the MSX Resource Center wiki by Gdx: fixed mains lead with a two-pin European plug.
- ↑ 5.0 5.1 5.2 File:Sanyo MPC-200 inside.jpg and File:Sanyo MPC-200 power supply area.jpg, photographs of an opened MPC-200 uploaded to the MSX Resource Center wiki by Rderooy: transformer PT0129, fuse holder F101 marked "T1A 250V", two large electrolytic capacitors side by side next to a part on a black heatsink, and a column of four diodes below them.
- ↑ MSX Cartridge slot, MSX Resource Center wiki—link(accessed 2026-10-21) Standard MSX cartridge slot pinout: pins 41 and 43 GND, 45 and 47 +5 V, 48 +12 V, 50 −12 V; +5 V up to 300 mA per slot; ±12 V up to 50 mA for all slots.
- ↑ 7.0 7.1 Sanyo, Instrucciones para el funcionamiento (MPC-200), page 14, "Especificaciones": video and RF outputs PAL; cassette FSK 1200/2400 baud; display TMS-9929A (equivalent). See Sanyo MPC-200 Operating Instructions.
- ↑ SANYO MPC-100 black & white video out error, January 2024—link(accessed 2026-10-21) Reply about Sanyo's PAL MPC-100: monitors made for NTSC regions cannot decode the PAL colour signal, so the picture appears in black and white.
- ↑ Toshiba T6950, MSX Resource Center wiki—link(accessed 2026-10-21) The T6950 supports all documented TMS9918-family screen modes; the first revision does not support the undocumented modes, in particular the mirrored modes, which makes a few games and demos incompatible; its palette differs slightly from the Texas Instruments chips.
- ↑ Sanyo, Instrucciones para el funcionamiento (MPC-200), page 4, "Conexión con el Cartucho": "Desconecte el computador antes de la conexión del Cartucho. Insértelo suavemente." See Sanyo MPC-200 Operating Instructions.
- ↑ File:Sanyo MPC-200.jpg, photograph uploaded to the MSX Resource Center wiki by Mars2000you, showing the "Atención" label beside the slots.
