Amstrad PC1640 Service Manual

The PC1640 Personal Computer, PC-MD Monochrome Display, PC-CD Colour Display, PC-ECD Enhanced Colour Display Service Manual is Amstrad plc's service manual for the PC1640 and its three monitors. It has 52 numbered pages; no date or part number is printed. This scan has 76 PDF pages, because the wide drawings are split across two images, and carries an OCR text layer.

Contents

Amstrad's contents list, with printed page numbers:

• Technical specification, p. 2; safety tests, p. 2
• FD-3 maintenance, pp. 3-14; flow charts, pp. 15-17
• Hard disc installation instructions, p. 18
• Switch settings, p. 19
• Understanding bad sectors on a hard disc, p. 20
• Notes, pp. 21-22
• Keyboard exploded diagram, p. 23; keyboard control PCB layout, p. 24; keyboard schematic diagram, pp. 24-25
• PC1640 electrical parts list, p. 26
• PC1640/SD/DD/HD20 cabinet drawing and parts list, p. 27
• PC1640/SD/DD/HD20 CPU PC board, p. 28; bottom view, p. 29
• PC1640/SD/DD/HD20 chassis schematic diagrams, pp. 30-35
• PC-MD electrical parts list, p. 35; cabinet and parts list, p. 36; main/CRT/volume PC board, p. 37; chassis schematic diagram, power supply, p. 38, and monitor, p. 39; alignment instructions, p. 40
• PC-CD electrical parts list, pp. 40-41; alignment instructions, p. 41; chassis schematic diagram, power supply, p. 42, and monitor, p. 43; main PC board, p. 44
• PC/ECD cabinet and parts list, p. 45; electrical parts list, p. 46; alignment instructions, p. 47; RGB, CRT and relay PC boards, p. 48; main PC board, p. 49; chassis schematic diagrams, TTL decoder, p. 50, power supply, p. 51, and monitor, p. 52

What it settles

Specification (p. 2)

The PC1640 has 640K of RAM with all circuitry on a single motherboard, an 8 MHz 8086, an internal graphics adaptor, three full-size expansion slots (also with the hard disc option), one or two 360K 5.25-inch floppy drives or one floppy and a 20 MB hard disc, serial and parallel ports, a loudspeaker with volume control, a battery-backed real-time clock and configuration RAM, a socket for an 8087, a light pen and joystick connector, a keyboard joystick port and a two-button mouse with its own port. The parts list gives the processor as an MBL8086-2P and the clock as an MC146818P at IC134.

The internal graphics adaptor gives 80-column text with 9 × 14 characters and EGA-compatible 640 × 350 monochrome graphics on the PC-MD; CGA modes and 200-line EGA on the PC-CD; and on the PC-ECD, 640 × 350 graphics in 16 of 64 colours. The ECD tube has a 0.31 mm shadow-mask pitch and the CD tube 0.42 mm.

PC1640 dimensions and weights (approximate, p. 2)

Unit	W × H × D (mm)	Weight unboxed	Weight boxed
PC-MD	350 × 315 × 300	8.0 kg	9.0 kg
PC-CD	370 × 320 × 360	11.5 kg	13.5 kg
PC-ECD	370 × 320 × 360	11.5 kg	13.5 kg
System unit SD	370 × 135 × 384	5.0 kg	8.9 kg
System unit DD		5.8 kg	10.5 kg
System unit HD		6.0 kg	11.0 kg

The safety tests are a 1.5 kV RMS flash test for 3 seconds between the mains poles and exposed metal, an insulation test at the same voltage requiring more than 4 MΩ, and an earth continuity test requiring the mains lead to be under 0.5 Ω.

Servicing note (p. 3)

The FD-3 flow charts are for information only, and faulty drive mechanisms are returned to Amstrad. Hard disc units must not be opened. The 20 MB drive came from two suppliers, ordered as 175037 (Alps) or 60001 (Tandon). Fault-finding uses the RP4 diagnostics card or the diagnostic disc. The FD-3 section lists a Dysan 224/2A CE diskette for alignment.

Switch settings (p. 19)

A 10-position DIP switch at the back of the system unit sets the display the internal graphics adaptor starts in, and has to be set for the monitor in use. Page 19 gives the switch positions for each named mode (MDTEXT, MDMONO, CDMONO, CDCOLOR, ECD200, ECD350) and marks the recommended setting for each monitor. The DISPLAY command can override the switches.

Hard disc and diagnostics (pp. 18-20)

Page 18 gives the procedure for reinstalling the system software on the hard disc: HDFORMAT, FDISK, FORMAT C:/S and CONFIG, run from system discs 1 and 4. Page 20 explains that Amstrad allows one bad sector per megabyte, or 200K on a 20 MB disc, that CHKDSK reports them, and that running HDFORMAT does not reduce them. It also describes the RP5-2 diagnostics card, which replaced the PC1512's RP4: it plugs into an expansion slot with an IC clip over IC108 (the lead with most wires to pin 10) and loopback plugs for the serial and parallel ports. RP4 cannot test the PC1640's displays, so on a PC1640 the display tests run from a disc supplied with the RP5-2, documented in the Amstrad PC1640 VDU Tests Manual.

Power supply alignment (pp. 40, 41, 47)

As on the PC1512, the power supply is in the monitor and feeds the system unit through a 14-way DIN socket. Each monitor's alignment table sets the rails for the whole computer with the same targets: +5 V to 5.10 V ±0.02 V, +12 V to 12.15 V ±0.02 V, −5 V to 5 V ±0.05 V, −12 V to 12.0 V ±0.05 V, and the +12 V overcurrent protection to trip at 4.5 A through a dummy load. The PC-MD uses presets VR505, VR504, VR501, VR502 and VR507 for these, plus VR503 for its own +12 V monitor rail (12.0 V at test point E); the PC-CD and PC-ECD use VR604, VR603, VR601, VR602 and VR606. The rest of each table covers the picture adjustments for that monitor.

What this manual does not contain

There is no service data for the hard disc beyond the installation and bad-sector pages. The display tests run by the RP5-2 disc are in the separate Amstrad PC1640 VDU Tests Manual, and the RP4 and RP5-2 cards themselves are not documented beyond the description on p. 20. The PC1512 has its own manual.

References

Download: Amstrad PC1640 Service Manual.pdf

Related pages

• Amstrad PC1640 VDU Tests Manual
• Amstrad PC1512 Service Manual
• Amstrad PC 2086 Service Manual
• Amstrad PPC 512 / PPC 640 Service Manual