Philips NMS 8250
 | |
| An NMS 8250 with one drive, its keyboard resting on top (photograph by Joxemai, CC BY-SA 4.0) | |
| Specifications | |
|---|---|
| Manufacturer | Philips (made by Sanyo)[1] |
| Type | MSX2 home computer |
| Released | 1986[1] |
| Intro price | ƒ1649 (Netherlands)[1] |
| CPU | Z80A[2] |
| Memory | 128 KB RAM, 128 KB video RAM, 48 KB ROM and 16 KB disk ROM[2] |
| Storage | One built-in 3.5-inch drive, 1 MB unformatted[2][1] |
| Display | Yamaha V9938[2] |
| Sound | PSG inside the S-3527 MSX controller[3] |
| Power | 220 V ±10 %, 50 Hz[2] |
| OS / Firmware | — |
| Model no. | NMS 8250/00, /16, /19[2] |
The Philips NMS 8250 is an MSX2 computer that Philips sold from 1986 in the Netherlands, Belgium, France and Spain. It is a desktop unit with a separate keyboard and one built-in 3.5-inch drive; the MSX Resource Center gives Sanyo as the manufacturer. The NMS 8255 is the same machine with a second drive, and both have "NMS 8250" on the front panel, so the label on the back is the way to tell them apart.[1] Philips covered the two in one service manual and one repair method.[2][4]
Specifications
[edit | edit source]| Item | Figure |
|---|---|
| Microprocessor | Z80A |
| Memory | 48 KB ROM, 16 KB disk ROM, 128 KB video RAM, 128 KB user RAM |
| Video processor | V9938 |
| MSX controller | S-3527 |
| Floppy disk drive | 3.5-inch, 1 MB |
| Interfaces | RF output (UHF channel E36), monitor output, SCART, cassette recorder, two joysticks, printer, two cartridge slots |
| Keyboard | QWERTY (/00, /16), AZERTY (/19) |
| Supply | 220 V ±10 %, 50 Hz |
Hardware
[edit | edit source]The machine has a main board, an analogue unit for the video and audio outputs, a power supply board, a cartridge connector unit and a keyboard interface panel, with the keyboard in its own case.[5] The main board ICs in Philips's parts list include these:[6]
| Position | Part | Function |
|---|---|---|
| IC145 | Z80A | CPU |
| IC101 | S-3527 | MSX controller, with the sound generator, keyboard, joystick, cassette and printer interfaces |
| IC106 | V9938 | Video processor |
| IC102 to IC105 | 81464-12 | Video RAM |
| IC133 to IC136 | 81464-12 | 128 KB user RAM in two banks of 64 KB |
| IC117, IC118, IC119 | ROMs | Disk ROM, expansion ROM and BASIC ROM; IC118 and IC119 differ between /00, /16 and /19 |
| IC153 | WD2793A | Floppy disk controller |
| IC162 | RP5C01 | Real-time clock with 26 × 4 bits of RAM |
The real-time clock keeps its settings on a NiCd accumulator on the main board (Philips part 4822 138 10213).[6] On the board in the photograph below it is a yellow cell printed "3.6V 45mAh".[8]
Power supply
[edit | edit source]The supply board U101 takes the mains through the line filter L901, fuse F1001 (2 A) and the switch SW901 to the transformer T901. One winding feeds the +5 V supply through F1050 (6.3 A), the bridge D1050 to D1053, a 22000 µF reservoir and IC1050, an SI-3052V regulator. A second winding feeds +12 V through the bridge D1054 to D1057, F1051 (1 A) and IC1051, a 7812, and −12 V through R1050 and IC1052, an AN79M12.[9] The circuit and its capacitors are on the Philips NMS 8250 Capacitor Replacement Guide.
Disk drive
[edit | edit source]Philips's drive parts list names the spindle motor together with its circuit board and lists no belt. The drive is aligned with Philips's FDD test cartridge 4822 397 30135 and alignment disk 4822 395 30274.[10]
Known problems
[edit | edit source]- Power supply rectifiers. On an NMS 8255, which uses the same supply, the rectifier diodes D1050 to D1053 were found coated in dust with the board darkened round them; replacing them cured a picture and sound level that rose slowly and then dropped. A member of the MSX Resource Center forum calls the supply's diodes "the usual suspects".[11][12]
- A black screen on one NMS 8250 turned out to be a failed PAL encoder on the video board.[12]
- The front panel becomes brittle with age.[1]
- SCC and other sound cartridges mix badly with the internal sound; the MSX Resource Center mentions modifications that fix it.[1]
Documentation
[edit | edit source]The service manual and the repair method are described on the Philips NMS 8250 Documentation page. The repair method is a fault-finding guide built round Philips's service test cartridge, with an error number for each test.[4]
Repair guides
[edit | edit source]- Philips NMS 8250 General Maintenance
- Philips NMS 8250 Troubleshooting Guide
- Philips NMS 8250 Capacitor Replacement Guide
Gallery
[edit | edit source]-
Main board (MSX Resource Center wiki). This board has been modified. -
Power supply circuit (service manual)
.png)
Related pages
[edit | edit source]- Philips NMS 8255, the two-drive version
- Philips NMS 8245, a one-piece MSX2 with a different main board and supply
- Philips NMS 8250 Documentation
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Philips NMS 8250, MSX Resource Center wiki—link(accessed 2026-10-21) Community specification page: almost identical to the NMS 8255, which has two drives where the 8250 has one, and both carry "NMS 8250" on the front; 128 KB RAM in slot 3-2 (not the 256 KB on the case, which adds the video RAM); models /00 (Netherlands and Belgium, QWERTY), /16 (Spain, QWERTY with ñ) and /19 (France and Belgium, AZERTY), all with a numeric keypad; brand Philips, manufacturer Sanyo; year 1986; launch price ƒ1649 in the Netherlands; Z80A from NEC (D780C-1) and Yamaha S3527 MSX-Engine with the PSG; MSX-DOS 1 and Home Office 2 on disk; "known for SCC (and other sound cards) mixing issues"; "the plastic front panel also gets very fragile with age"; connections: RF, audio and composite video, luminance output, SCART RGB, keyboard, data recorder, Centronics printer, two general-purpose ports and two cartridge slots on the right-hand side.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Philips, Service Manual, Home computer NMS8250/00/16/19, NMS8255/00/16/19, cover CS 7 567, PDF page 1: specification. Hosted as File:Philips NMS 8250 and NMS 8255 Service Manual.pdf.
- ↑ Philips, Repair Method NMS8250/NMS8255, order code 4822 727 15847, printed page 12: "The registers in the sound generator (integrated in the S-3527) are tested by the sound test." Hosted as File:Philips NMS 8250 and NMS 8255 Repair Method.pdf.
- ↑ 4.0 4.1 Philips, Repair Method, Home computer NMS8250/00/16/19, NMS8255/00/16/19, order code 4822 727 15847, cover CS 7 946. Hosted as File:Philips NMS 8250 and NMS 8255 Repair Method.pdf.
- ↑ Philips, Service Manual NMS8250/NMS8255, PDF page 38: mechanical parts list. 1 front panel 4822 432 10591; 2 keyboard upper case; 3 keyboards /00, /16 and /19; 4 caps LED (U109); 6 keyboard lower case; 7 floppy drive (U104) 4822 693 91114; 8 power-on LED (U110); 9 mains switch; 11 keyboard interface panel (U105); 13 reset switch (U108); 15 transformer 4822 148 60157; 16 analog unit (U102) 4822 219 80953; 17 power supply (U101) 4822 219 80954; 18 main panel /00, /16, /19 (U100); 19 keyboard cable; 23 floppy drive (U103) 4822 693 91114; 24 SCART connector; 26 to 28 audio, video and luminance output connectors; 29 modulator; 31 keyboard connector; 32 printer connector; 33 and 34 joystick connectors; 35 recorder connector; 37 cartridge connector unit (U107); 38 cartridge holder. Hosted as File:Philips NMS 8250 and NMS 8255 Service Manual.pdf.
- ↑ 6.0 6.1 6.2 Philips, Service Manual NMS8250/NMS8255, PDF page 36 (repeated as page 37): main printed board parts list. U100 main printed board /00 4822 219 80952, /16 4822 219 80961, /19 4822 219 80962; IC101 S-3527; IC102 to IC105 81464-12; IC106 V9938; IC117 disk ROM; IC118 expansion ROM /00, /16, /19; IC119 BASIC ROM /00, /16, /19; IC133 to IC136 81464-12; IC145 Z80A; IC153 WD2793A; IC162 RP5C01; IC173 AN1431T; X102 32.768 kHz; X103 4 MHz; X104 21.47727 MHz; RL101 relay; Ni-Cd accumulator 4822 138 10213; L101 coil; SW101 service switch; TH101 NTC SDT-100; VR102 50 kΩ; VR104 10 kΩ. Hosted as File:Philips NMS 8250 and NMS 8255 Service Manual.pdf.
- ↑ Philips, Repair Method NMS8250/NMS8255, 4822 727 15847: printed page 3 (video data line checks name IC102 to IC105 with IC106), page 4 (keyboard pins on IC101), page 5 (joystick pins on IC101), page 6 ("The NMS8250 has a 128k users RAM divided over two banks of 64k. IC133 and IC134 form bank 1 and IC135 and IC136 form bank 2"), page 11 (cassette signal from IC101), page 12 (sound generator in the S-3527, IC101), page 16 (sum checks of IC117, IC118 and IC119), page 17 (RTC with 26 × 4 bit RAM, IC162), page 18 (printer lines on IC101), page 21 (floppy disk interface errors, IC153). Hosted as File:Philips NMS 8250 and NMS 8255 Repair Method.pdf.
- ↑ File:Philips NMS 8250 main board.jpg, photograph of an NMS 8250 main board (Sanyo board EB1921) uploaded to the MSX Resource Center wiki by Gdx, 15 March 2016: a yellow cell printed "3.6V 45mAh" at the bottom left. The board carries two added EPROMs labelled "FAST-DISK V.1.08" and "EXT. BASIC V.2.11", so it has been modified.
- ↑ Philips, Service Manual NMS8250/NMS8255, PDF page 20 (sheet CS 7 580): power supply U101 circuit diagram. Hosted as File:Philips NMS 8250 and NMS 8255 Service Manual.pdf; the supply part is reproduced as File:Philips NMS 8250 power supply circuit (service manual).png.
- ↑ Philips, Service Manual NMS8250/NMS8255, PDF pages 2, 3 and 5: floppy disk drive alignment (dual-trace oscilloscope such as the PM3211, alignment disk 4822 395 30274, FDD test cartridge 4822 397 30135, started with POKE &HFD9F,&HC9 and CALL FDDTEST) and the FDD exploded view and parts list (write protect switch assembly, spindle motor + PCB, track 00 sensor, complete printed board, carriage assembly, eject hook bracket, stepper motor, eject bracket, disk detect switch assembly). Hosted as File:Philips NMS 8250 and NMS 8255 Service Manual.pdf.
- ↑ Philips NMS-8255 power (?) supply question and modding, July and August 2010—link(accessed 2026-10-21) Wild_Penguin, 16 and 17 July 2010: picture brightness and PSG level rose gradually and then dropped, once with a hang; the rectifier diodes D1050 to D1053 had a coat of dust, the board was darkened round them, and replacing them solved the problem; the supply has a soldered-wire jumper for 220 V or 230 V. 10 August 2010: +5 V correct off load but about 5.78 V with the main board connected, and higher with the drives disconnected; the +5 V electrolytic was changed (1000 µF, 10 V). RetroTechie: check the solder joints of the +5 V regulator; the rectifier diodes "regularly fail". 15 August 2010: measured on a PC supply, about 1.50 A at +5 V, 1.56 to 1.60 A with a drive working; 0.22 A at +12 V, 0.3 A with a drive working.
- ↑ 12.0 12.1 NMS 8250 broken, February and March 2023—link(accessed 2026-10-21) rolandve, 20 February 2023: an NMS 8250 (upgraded to MSX2+ with a second drive) gave a black screen while the drive made repeated noises, then the drives stopped. Daemos: check the voltages first, the power supplies "are notorious for long term failures" and "the diodes are your usual suspects"; look for ripple with a scope. larsthe18th: check the white switch SW101 in the centre of the main board in case it was pressed. Repair-Bas, 14 March 2023: "Pal encoder was broken"; rolandve: "a new video board".