Amstrad DMP2000 Maintenance Guide
The Amstrad DMP2000 has a mains power supply on its main board and a 9-pin print mechanism with separate carriage and line-feed motors. Amstrad's service manuals give parts lists and diagrams but no adjustment or fault-finding procedures, so this maintenance work rests on those lists and the user instructions. The Amstrad DMP3000 shares the mechanism and the main board, and its maintenance guide covers the differences.[1][2]
Safety
[edit | edit source]Warning: the printer contains mains voltage on its filter board, transformer and power switch. Unplug it before removing the cover screws.
Amstrad's note in the service manual is that parts with its safety prefix must be replaced only with parts of identical safety specification, and that safety tests must be carried out after any work.[1] The safety items in the electrical parts list include the power switch, the mains transformer, the mains filter coil and the 250 V capacitors C31 to C34. The wiring diagram marks the mains filter board "Warning live parts".[1]
The user instructions ask for a 3 A fuse in a 13 A plug and a 220–240 V 50 Hz supply.[2]
Things that damage the mechanism
[edit | edit source]Amstrad's user instructions list these as operating rules:[2]
- Do not run the printer with the ribbon removed.
- Do not run it with no paper loaded.
- Do not switch on with the cardboard print head stabiliser in place. A printer that has been stored or shipped with a stabiliser fitted needs it removed first, along with the cardboard inserts at the front and on top of the head.
- Do not block the ventilation slots, and keep the printer out of hot, cold, damp or dusty places.
- Switch the printer off before changing the DIP switches.
Ribbon
[edit | edit source]The ribbon is a cassette rated at one million characters, Amstrad part SOFT06049.[1] To fit it:[2]
- Lift off the clear cover by hinging it backwards.
- From the rear, locate the two metal ribbon brackets. Fit the right-hand plastic end into its bracket: bottom into the square hole first, then clip the top in.
- Pinch the two small flaps on the other end, fit it into the other bracket and release the flaps.
- Lift the small head lever to the right of the print head, slide the upper ribbon under the grooved flap, and release the lever.
- Slide the lower ribbon between the bottom of the print head and the small metal shield.
Removal is the reverse. Faint or uneven self-test printing is the first sign of a ribbon or paper loading problem.[2]
Self test
[edit | edit source]Switch the printer off, hold down LF, switch on and release LF. The printer prints the ASCII character set until the paper runs out or it is switched off. Amstrad suggests switching off after four or five lines and checking that the characters are clear and even.[2] The self test needs no computer, so it separates a printer fault from a cable, interface or software fault.
On a normal start with paper loaded, the paper-out alarm does not sound and the ON LINE lamp lights. With no paper, the head moves, the bleeper sounds, and the POWER and PAPER OUT lamps stay lit.[2] DIP switch DS1-5 disables the paper-out sensor and DS2-6 enables or disables the bleeper.[1]
Print head and mechanism
[edit | edit source]The print head is supplied as one part with its ribbon mask (190813), and the carriage carries a flexible print cable (Set FPC, 190797).[1] The user instructions describe the paper-thickness knob: moving it down darkens the print, and moving it up lightens it and allows thicker paper or two sheets.[2] The mechanism parts list also gives the carriage motor (190771), the line-feed motor (190752), the platen (190749), the carriage shaft (190759), the paper-end sensor assembly (190767) and felt parts on the carriage (felt ring 190760, upper felt 190765).[1]
- With the printer unplugged, move the carriage by hand along its shaft and check that it runs smoothly from end to end.
- Clean paper dust and ribbon fibres from the carriage shaft, the platen and around the head with a soft brush.
- Inspect the flexible print cable where it flexes as the carriage moves.
Opening the case
[edit | edit source]Amstrad's cabinet drawing (p. 5) shows the top cabinet (1) with the dust cover (3) and the rotary paper-feed knob (4), the mechanism fixed to the bottom cabinet (2), and the shield plate (5) between the mechanism and the main board.[1] The DIP switches are reached from the rear of the printer without opening it.[2]
- Unplug the mains lead and the printer cable, remove the paper and the ribbon, and lift off the clear cover.
- Pull off the paper-feed knob.
- Turn the printer over and remove the screws holding the top cabinet to the bottom cabinet.
- Lift the top cabinet away, noting the control panel cable to the main board.
Power supply and capacitors
[edit | edit source]The transformer feeds two bridge rectifiers on the main board, an S4VB10 (BD1, 4 A 100 V) and an S2VB10 (BD2, 2 A 100 V); an L7805CY regulator (IC18) makes the 5 V supply.[1][3] Amstrad's DMP2000/3000 electrical parts list gives only three electrolytic entries, and two of them conflict with Schneider's fuller list for the same board:
| Ref | Amstrad DMP2000/3000 list | Schneider DMP3000 list |
|---|---|---|
| C4 | 1 µF 50 V (printed "C1, 4") | 1 µF 50 V, 105 °C |
| C25 | Not listed | 4700 µF 30 V, 105 °C |
| C26 | 47 µF 16 V | 47 µF 16 V, 105 °C |
| C28 | "4700pF/16V" | 4700 µF 16 V, 105 °C |
Amstrad's list also gives C1 as a 0.1 µF mono glass capacitor in the same table, so the "C1, 4" electrolytic entry is a misprint for C4 alone, as Schneider's list has it. C28's "4700pF" is a misprint for 4700 µF, the value in Schneider's list; the wiring diagram draws C25 and C28 as two large capacitors beside the bridge rectifiers.[1][3] Fit C25 at 4700 µF with at least the 30 V rating Schneider gives, and C28 at 4700 µF 16 V or higher. See Capacitor Failure Symptoms.
The 250 V capacitors on the mains side are safety items. Amstrad's list gives C31 and C34 as 0.047 µF 250 V and C32 and C33 as 0.0022 µF 250 V; Schneider's English column prints C32 and C33 as 0.022 while its German column agrees with Amstrad.[1][3] Replace them only with mains-rated parts of the same value.
| Fuse | Schneider DMP3000 list (p. 11) | Amstrad wiring diagram (p. 8) |
|---|---|---|
| F1 | T3.15 A 250 V | On the main board beside BD2; no rating printed |
| F2 | T315 mA 250 V | On the mains filter board, printed "250V/150mA" |
The two documents disagree on F2. Read the rating printed on the fuse fitted, and on the board beside it, before replacing it.[3][1]
Interface
[edit | edit source]The Centronics socket follows the standard pinout; pin 18 supplies +5 V at up to 50 mA and pin 31 (INPUT PRIME) resets the printer when taken low.[1] If the self test prints correctly but the computer cannot print, check the cable, the ON LINE lamp, and the DIP switches that set the character set and 7- or 8-bit codes (DS1-1 to DS1-3 and DS1-7).[1][2]
Tools
[edit | edit source]- Cross-head screwdrivers
- Digital multimeter
- Soft brush, lint-free cloth and isopropyl alcohol
- A replacement ribbon cassette
- See Recommended Tools.
Related pages
[edit | edit source]- Amstrad DMP2000 · Amstrad DMP3000 · Amstrad DMP3000 Maintenance Guide
- Amstrad DMP2000 / DMP3000 / DMP4000 Service Manual · Amstrad DMP2000 Printer Service Manual (standalone) · Schneider DMP3000 Service Manual
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Amstrad plc, DMP2000 / DMP3000 / DMP4000 Printer Service Manual. Hosted as File:Amstrad DMP2000 DMP3000 DMP4000 Service Manual.pdf, described at Amstrad DMP2000 / DMP3000 / DMP4000 Service Manual. Specifications and safety note p. 2; interface and DIP switches p. 3; cabinet parts list p. 4; cabinet drawing p. 5; mechanism and mechanism parts list pp. 6–7; wiring diagram pp. 8–9; circuit diagram pp. 10–11; electrical parts list p. 12.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 Amstrad, DMP2000 User Instructions, second edition, autumn 1985. Hosted as File:Amstrad DMP2000 User Instructions.pdf, described at Amstrad DMP2000 User Instructions. Introduction (safety notes); chapter 1 pp. 1–11 (mains plug, print head stabiliser, ribbon, paper loading, controls, self test); chapter 2 (DIP switches).
- ↑ 3.0 3.1 3.2 3.3 Schneider, Kundendienst-Handbuch / Service Manual DMP 3000, Ident-Nr. 33 624. Described at Schneider DMP3000 Service Manual. Electrical parts list p. 10; miscellaneous parts and fuses p. 11.