Sinclair ZX Printer
| Sinclair ZX Printer | |
|---|---|
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| Sinclair ZX Printer (photo: Carlos Pérez Ruiz, CC BY-SA 2.0, Wikimedia Commons) | |
| Manufacturer | Sinclair Research |
| Type | Spark (electrosensitive) printer |
| Release date | Announced early 1981; on sale late 1981[1][2] |
| Discontinued | 1984[1] |
| Price | £49.95 (1981)[1][2] |
| Interface | Rear edge connector of the ZX81 or ZX Spectrum, read and written at I/O port 251 (FBh)[3] |
| Compatible | Sinclair ZX81, Sinclair ZX Spectrum, Sinclair ZX80 with the 8K ROM[1] |
| Model | ZX Printer |
| Power | From the computer's edge connector: +5 V and the unregulated supply line; +50 V for the styli made inside the printer[4][5] |
| Resolution | 256 dots (32 characters) per line[1][5] |
| Media | 100 mm (4 in) aluminium-coated paper on a reel[1] |
The Sinclair ZX Printer is a small spark printer that Sinclair Research sold for the Sinclair ZX81 and later the Sinclair ZX Spectrum. It prints on 100 mm paper coated with a thin layer of aluminium: a stylus passes a current through the coating, which burns away to show the black backing, giving 32 characters or 256 dots to a line.[1] It plugs into the computer's rear edge connector and takes its power from it. Inside are a Ferranti ULA, type 1026, seven transistors (one of them the encoder's phototransistor), a motor, an optical encoder and a belt carrying two styli.[6][4][5]
The Ferranti Archives 2026 hold Ferranti's logic and pad-circuit drawings of the ULA from 1981 and a hand-drawn circuit of the printer dated 2 March 1982. With Sinclair's own servicing manual, they cover the whole electronics.
History
[edit | edit source]Sinclair announced the printer alongside the ZX81 in early 1981, at £50. It was on sale later that year at £49.95; Planet Sinclair gives the launch as November 1981.[1][2] A London shop's ZX81 stock list of 2 November 1982 in the Ferranti files prices it at £59.95 and notes that it "can be used with both ZX81 and Spectrum".[7] It also worked with the Sinclair ZX80 fitted with the 8K ROM.[1]
The printer drew its power from the computer. Sinclair's ZX81 kit instructions ask for a supply of at least 600 mA, or 1.2 A if the printer runs from the same supply; the printer was sold with a larger adaptor for the ZX81, and the Spectrum's own adaptor was enough.[8][1]
Sinclair discontinued the ZX Printer in mid-1984. A spokeswoman told Sinclair User that "we were selling only thousands and sales have fallen", and Sinclair said it had no plans for a replacement.[1] The printer was not sold in the United States because it could not pass the FCC's emissions rules; Timex sold the Alphacom 32, a thermal printer using the same interface, as the Timex Sinclair 2040.[1] Planet Sinclair calls the TS 2040 a rebadged ZX Printer; Wikipedia's sources and forum members who own one describe it as the Alphacom 32, a thermal printer.[2][9]
How it prints
[edit | edit source]Sinclair's servicing manual describes the mechanism:[5]
- Two hairpin-shaped styli ride on an endless, internally toothed plastic belt running round two pulleys. Each pass of a stylus across the paper prints one row of dots.
- The printer generates about 50 V and routes it to a metal conductor strip in the top cover. One end of each stylus runs on the strip and the other on the paper; the current returns through the paper's metal coating to the conductive rubber feed roller and so to earth in the electronics.
- Before reaching the paper, each stylus passes over an L-shaped insulating wafer. The control electronics sense the moment the stylus leaves the wafer and touches the paper, and from then on pulse the 50 V to print.
- The motor drives the belt through bevel gearing, the paper feed roller through two wormshafts, and an encoder disc through a spur gear. An LED and a photodiode either side of the disc give 1024 pulses across the printing width, divided by four to 256 so that each dot is placed to within a quarter of its width.
- A FEED button on the top cover runs the paper through without printing.
The paper's metal surface is delicate. Planet Sinclair notes that fingerprints damage it, that printouts fade, and that magazines published listings by photocopying ZX Printer output.[2] Sinclair warned that only its approved paper should be used and that adjusting the printer to suit other papers could wear the mechanism.[5]
Specifications
[edit | edit source]| Item | Detail |
|---|---|
| Printing | Two styli on a belt; spark erosion of aluminium-coated paper[5][1] |
| Line | 256 dots, 32 characters[1] |
| Paper | 100 mm (4 in) wide, aluminium-coated, on a reel[1] |
| Stylus supply | About 50 V, made in the printer from the computer's unregulated supply; measured on C4[5][4] |
| Logic supply | +5 V from the computer (edge contact 1B)[4] |
| Controller | Ferranti ULA 1026 (IC1), 18 pins on the 1982 circuit[6][4] |
| Computer interface | I/O port 251 (FBh); the ULA decodes only A2, with /IORQ and /RD or /WR[3][6] |
| Encoder | Slotted disc, LED D3 and phototransistor Tr9; 1024 pulses across the line, divided by four[5][4] |
Hardware
[edit | edit source]
The ULA 1026
[edit | edit source]The printer's controller is a Ferranti ULA, type 1026. Ferranti's logic diagram LD6611/ULA1026/1 is issue 1 of 31 March 1981, and the pad-circuit drawing ULA 1026/2 is issue 1 of 25 May 1981; the archive holds two prints of each.[6][10] The drawing style and title block are the same as on Ferranti's ZX81 ULA drawings.[6]
| Pin | Signal | Connection on the 1982 circuit | Pin circuit (Ferranti 1026/2) |
|---|---|---|---|
| 1 | 0 V | Ground | – |
| 2 | PHOTO I/P | Encoder phototransistor Tr9, through C10 (10 nF) | Comparator-based Schmitt input ("Schmitt type 3") |
| 3 | MOTOR SPEED RC | R13 (100 kΩ) to +5 V and C8 (4.7 nF) to ground | Open-collector discharge transistor and a Schmitt input ("type 1") |
| 4 | PAPER I/P | Paper-detect divider R9 (47 kΩ), R10 (1 MΩ), R11 (1 MΩ), C6 (10 nF) | Emitter-follower input into a Schmitt trigger |
| 5 | /RD | Edge contact 16A (white wire) | Emitter-follower input, 5K to ground |
| 6 | /WR | 17A (pink) | As /RD |
| 7 | /IORQ | 15A (grey) | As /RD |
| 8 | A2 | 9B (yellow) | As /RD |
| 9 | D6 | 7A (blue) | Open-collector output |
| 10 | D0 | 4A (black) | Tri-state output |
| 11 | D7 | 1A (violet) | Tri-state output and emitter-follower input |
| 12 | ZAP O/P | Base of the stylus switch Tr3 | Emitter-follower output through 600 Ω |
| 13 | D1 | 5A (brown) | As /RD |
| 14 | D2 | 6A (red) | As /RD |
| 15 | FEED / CLEAR | FEED button S1 to ground, R17 (10 kΩ), C5 (47 nF) | 500K pull-up, emitter follower into a Schmitt trigger ("type 2") |
| 16 | BRAKE O/P | Not connected | Transistor with 10K pull-up |
| 17 | MOTOR O/P | Base of the motor transistor Tr6 | As ZAP, with 150 Ω in place of 600 Ω |
| 18 | +5 V | Edge contact 1B (orange) | – |
Pin functions and circuits are from Ferranti's two drawings; the board connections are from the 1982 circuit, which agrees with the ULA drawing on every pin number. The ULA drawings do not show the supply pins.[6][10][4]
The chip decodes only A2. A2, /IORQ and /WR form the write strobe and A2, /IORQ and /RD the read strobe; no other address line reaches it.[6] Writes are latched from D1, D2 and D7, and status is returned on D0, D6 and D7.[6] This matches Sinclair's documentation: the Spectrum manual gives port 251 (binary 11111011, A2 low) as the printer port, and the Spectrum ROM writes bit 1 to slow the motor, bit 2 to stop it and bit 7 to print, and reads bit 0 for the encoder, bit 6 to see whether a printer is present and bit 7 to wait for the stylus.[3][11] The BRAKE output exists on the chip but is not connected on the 1982 circuit.[6][4]
The printer circuit
[edit | edit source]The hand-drawn circuit "ZX Printer Electronics (2 Mar 82)" carries no company name or drawing number.[4] Figure 7 of Sinclair's servicing manual is the same circuit, redrawn; it names the 47 nF capacitor across the motor as C9 and gives R16 as 1 kΩ, a value that cannot be read on the 1982 sheet.[5][4]
+5 V arrives on edge contact 1B. The computer's unregulated supply arrives on 2B and passes through L1, with C1 (47 nF) and C2 (100 µF 16 V), to become the "+10V nom" rail.[4]
Tr1 (BC214) and Tr2 (ZTX651), with a two-winding transformer, R1 to R4 and C3 (10 µF), form what the servicing manual calls "a self regulating 50V power supply". D1 rectifies into the reservoir C4 (100 µF 63 V), and the manual says to measure the 50 V on C4.[4][5]
ULA pin 12 drives Tr3 (BC182), which switches Tr4 (ZTX551) to put the 50 V on the stylus line: "TR3 and TR4 switch the 50V to the stylus in order to generate printing."[4][5] The stylus line reaches the conductor strip in the top cover by a white wire with a push-on connector; the ROLLER terminal and the feed roller's earth terminal (green wire) go to 0 V.[4][5]
When the stylus first touches the paper at the left-hand margin, Tr5 (ZTX551) is switched on through R8 (100 kΩ) and raises ULA pin 4 through R9 and R11, and the ULA then passes the encoder signal to the computer. The manual says C6 and R11 stop contact being lost momentarily and are "critical in value", and that Tr5, a ZTX550 on some early printers, should be replaced by a ZTX551 because of problems with devices giving too much gain.[5][4]
ULA pin 17 drives Tr6 (ZTX451), which switches the motor from the +10 V rail; D2 and C9 (47 nF) sit across the motor. During the last two lines of a print the motor runs slowly: the ULA switches Tr6 on and off using the R13 and C8 time constant on pin 3 together with the encoder signal. The motor also has an internal varistor ring suppressor.[4][5]
The encoder LED D3 is fed from +5 V through R15 (150 Ω) and sits on flying leads in the base insert. The phototransistor Tr9 is soldered to the board with R14 (470 Ω) and R16, and its emitter feeds ULA pin 2 through C10 (10 nF); C11 (10 µF) is also in this part of the circuit. The manual asks for more than 200 mV peak to peak at pin 2 in operation.[4][5] The FEED button S1 pulls ULA pin 15 to ground, with R17 (10 kΩ) and C5 (47 nF).[4]
Edge connector wiring
[edit | edit source]| Wire | Contact | Signal (printer circuit) | Signal (Sinclair ZX81 manual) |
|---|---|---|---|
| Orange | 1B | +5 V | 5V |
| Turquoise | 2B | Unregulated supply, to L1 | 9V |
| Yellow | 9B | A2 (ULA pin 8) | A2 |
| Violet | 1A | D7 (pin 11) | D7 |
| Black | 4A | D0 (pin 10) | D0 |
| Brown | 5A | D1 (pin 13) | D1 |
| Red | 6A | D2 (pin 14) | D2 |
| Blue | 7A | D6 (pin 9) | D6 |
| Grey | 15A | /IORQ (pin 7) | IORQ |
| White | 16A | /RD (pin 5) | RD |
| Pink | 17A | /WR (pin 6) | WR |
| Screen | 4B, 5B | 0 V | 0V, 0V |
The contact numbers and colours are from the 1982 circuit (the screen contacts are written "48,5B" there and "48,53" in the servicing manual); the right-hand column is the edge-connector list printed in Sinclair's ZX81 manual, which agrees on every contact.[4][5][12] The printer's connector also carries the bus through to the back, so other add-ons can plug in behind it.[1]
Capacitors
[edit | edit source]| Ref | Value | Type | Position |
|---|---|---|---|
| C1 | 47 nF | Ceramic | Supply input at L1 |
| C2 | 100 µF 16 V | Electrolytic | +10 V nominal rail after L1 |
| C3 | 10 µF, rating not given | Electrolytic | +50 V converter, Tr1 and Tr2 |
| C4 | 100 µF 63 V | Electrolytic | +50 V reservoir after D1 |
| C5 | 47 nF | Ceramic | FEED input, ULA pin 15 |
| C6 | 10 nF | Ceramic | Paper-detect divider to ULA pin 4 |
| C7 | 47 nF | Ceramic | +5 V decoupling |
| C8 | 4.7 nF | Ceramic | Motor speed RC, ULA pin 3 |
| C9 | 47 nF | Ceramic | Across the motor (unlabelled on the 1982 sheet) |
| C10 | 10 nF | Ceramic | Encoder coupling to ULA pin 2 |
| C11 | 10 µF, rating not given | Electrolytic | Encoder phototransistor circuit |
Values are from the 1982 circuit, with C9's designator from the servicing manual; the electrolytics are identified by their symbols.[4][5] Neither drawing gives a voltage rating for C3 or C11. Retroleum's replacement set for the printer uses 16 V parts for both, with 100 µF 16 V for C2 and 100 µF 63 V for C4.[13]
Troubleshooting
[edit | edit source]The ZX Printer is now over forty years old, and suitable paper is hard to find.[2] The table combines the fault list in Sinclair's servicing manual with period and community reports. Notes marked as reasoning are drawn from the circuit; no recorded repair stands behind them.
| Symptom | Probable cause | Action |
|---|---|---|
| Vertical zig-zag in the print, usually worse on the right | Worn belt | Fit a new belt[5] |
| Horizontal lines unevenly spaced | Worn belt | Fit a new belt[5] |
| Print fading over part of the line | Dirt on the conductor strip in the top cover | Clean the strip and apply a thin coat of Electrolube[5] |
| "Noisy" printing | Too much gain on Tr5, or too little signal from the encoder | Fit a ZTX551 in place of a ZTX550 at Tr5; Sinclair's remedy for a weak encoder signal was a new ULA[5] |
| Badly formed characters, loss of print synchronisation | Dust and metallised paper particles in the encoder disc cavity | Clean the cavity and the disc with a soft brush; do not oil the gears[14][5] |
| No print, paper all black | Tr4 | Replace Tr4[5] |
| No print, no image at all | White wire off the conductor strip; no 50 V; dirty or failed LED or photodiode | Reconnect the white wire and check for 50 V on the strip and on C4; clean or replace D3 and Tr9[5] |
| Motor does not run | Conductor strip loose in the top cover; motor bevel pinion touching the motor mounting screws | New top cover assembly; check the screws and reset the gear mesh[5] |
| Motor runs slowly | Friction on the encoder disc; too much gain on Tr5 | Slightly slacken the base insert screw near the disc; fit a ZTX551 at Tr5[5] |
| Paper does not feed | Weak pinch roller springs; paper reel ends jammed against the cover | Fit 0.60 mm wire springs; wind the reel tightly so it clears the cover[5] |
| Paper does not feed after the printer has stood unused | The roller deforms the paper and cannot overcome the reel's starting torque | Your Computer (1984) joined the two reel hubs with a tight-fitting tube about 97 mm long[14] |
| Light and dark bands across the print | Uneven metallisation of the paper | Try another roll[14] |
| Belt broken, styli loose | The original belt has failed | Rebuild with a flat VCR belt and the original styli, or fit a 3D-printed replacement; see Belt and styli[15][9] |
| Drive screeches | Dry bearings, dirty gears | Clean; the servicing manual lubricates the bushes lightly with Molycote 44 and does not lubricate the gears or wormshafts[5][14] |
Electrical checks
[edit | edit source]| Check | Detail |
|---|---|
| +50 V | Measure on C4.[5] If it is missing, the converter is the first suspect: Tr1, Tr2, D1, the transformer and C4, and the +10 V rail from edge contact 2B through L1 with C2 (reasoning from the circuit). C4 is a 63 V capacitor working on a nominal 50 V rail and one of only four electrolytics in the printer, so it deserves a check on any printer that has stood for years (reasoning).[4] |
| Encoder | More than 200 mV peak to peak at ULA pin 2 while the printer runs; an oscilloscope on the emitter of Tr9 shows whether the phototransistor works. Sinclair's list of common encoder faults: an over-etched disc, a disc working loose, a badly formed slot in the base frame in front of the phototransistor (some printers have a metal shim with a photo-etched slot), and dirt on the disc or in front of the phototransistor.[5] |
| Paper detect | Tr5, R8, R9, R11 and C6 raise ULA pin 4 when the stylus touches the paper. The Spectrum ROM waits for this signal (bit 7 of port 251) before printing each line, so a paper-detect fault would leave the motor running with nothing printed (reasoning from the circuit and the ROM).[5][11] |
| Motor | Tr6 switches the motor from ULA pin 17. A motor that never runs with the mechanism free points at Tr6, D2 or the motor; a motor whose speed is wrong points at the encoder signal and at R13 and C8 on pin 3 (reasoning from the circuit description).[4][5] |
| Printer not found | The ROM reads bit 6 of port 251 to decide whether a printer is present, and on the printer that bit comes from the ULA's open-collector D6 output on the blue wire to 7A. A printer that the computer ignores points at the ribbon, the edge connector, the +5 V on 1B or the ULA (reasoning).[11][6][4] |
| Clashes with other add-ons | The ULA decodes only A2, so another add-on that answers I/O cycles with A2 low will clash with the printer (reasoning from the decode logic). The Spectrum manual describes each of A0 to A4 as selecting one device, with no more than one of them low at a time.[6][3] |
Belt and styli
[edit | edit source]The servicing manual's procedures cover the belt and styli: lift off the top cover (four screws in the base; disconnect the white wire from the conductor strip as the cover comes up), lift the belt off its pulleys, and refit it with the styli at the outer edges of the pulleys in the trailing position; the belt turns clockwise viewed from the top. A stylus fits over a spigot on the belt with the longer foot outside the belt, held by a push-on cap.[5]
Original belts are now often found broken, with the styli and belt pieces still in the printer.[9] Two repairs are in circulation:
- Fabio Rizzo's 2008 guide rebuilds the belt from a flat VCR belt 5 mm high, 1 mm thick and cut to 275 mm, with new spigots made from staples 137.5 mm apart, trimmed to 2.5 mm, and caps cut from wire insulation. He warns that spigots that are too tall stop the belt turning, and that overtightening the four cover screws affects printing.[15]
- Forum members have designed 3D-printed belts in flexible filament. One found the first belts too tight to turn and, after rescaling the print, had one working at 101 per cent of the design size; another pointed out that the original belt is thin because the pulleys run in thin-walled plastic bearings driven by a weak motor, so a stiff or tight belt can break the bearings or stall the motor.[9]
Cleaning
[edit | edit source]Metallised dust from the paper builds up inside the printer. Sinclair's manual removes it with a gentle air blast or a soft brush and warns never to use solvents or other fluids, which can attack the plastic and rubber parts.[5] The 1984 Your Computer article opened the base to clean the encoder cavity and warned against oiling the gears, because oil holds dust and can reach the optical surface; a later issue of the magazine warned against its suggested use of butter as a bearing lubricant.[14]
Documentation
[edit | edit source]- Servicing Manual for ZX Printer (Sinclair Research): principle of operation, circuit description, fault table, removal and installation procedures, and the circuit diagram.[5]
- Ferranti Archives 2026: PRN-SIN-SCH-012 (printer circuit, 2 March 1982), PRN-FER-SCH-106 (ULA 1026 logic) and PRN-FER-SCH-010 (ULA 1026 pad circuits), with second prints PRN-FER-SCH-117 and PRN-FER-SCH-116.
- The archive also holds several ZX81 program listings printed on a ZX Printer, among them ZX81-UNK-COD-132.
Related pages
[edit | edit source]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 1.14 1.15 "ZX Printer", Wikipedia, https://en.wikipedia.org/wiki/ZX_Printer (retrieved 2026-10-18). Citing Personal Computer World (May 1981) for the announcement, Your Computer (October 1981) for "Available Now ... £49.95", Sinclair User (July 1984) for the discontinuation, and ZX Computing (October 1984) for the FCC and the Timex Sinclair 2040. Source for the history, paper, resolution, power arrangements, through connector and compatibility.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Chris Owen, "ZX Printer", Planet Sinclair, https://rk.nvg.ntnu.no/sinclair/computers/peripherals/zxprinter.htm (retrieved 2026-10-18). Source for the November 1981 launch at £49.95, the fragile paper and photocopied listings, and the incorrect TS 2040 description.
- ↑ 3.0 3.1 3.2 3.3 Sinclair Research, ZX Spectrum BASIC Programming manual, chapter 23, "IN and OUT". Transcribed at https://worldofspectrum.net/ZXBasicManual/zxmanchap23.html (retrieved 2026-10-18). Source for port 251 as the printer port and for A0 to A4 each selecting one device.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 "ZX Printer Electronics (2 Mar 82)", hand-drawn circuit diagram, Ferranti Archives 2026 (PRN-SIN-SCH-012). Source for the board circuit, component values, ULA pin connections, the unconnected BRAKE pin and the ribbon colours and contacts.
- ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21 5.22 5.23 5.24 5.25 5.26 5.27 5.28 5.29 5.30 5.31 5.32 5.33 5.34 Sinclair Research Ltd, Servicing Manual for ZX Printer. Hosted as File:Sinclair ZX Printer Servicing Manual.pdf. Section 1 (principle of operation), section 2 (system, logic and circuit description, including the 50 V test point, Tr5, the 200 mV encoder figure and the slow-motor action), section 3 (fault diagnosis table), section 4 (removal and installation, cleaning and lubrication), Figures 6 and 7.
- ↑ 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 Ferranti logic diagram LD6611/ULA1026/1 for the ZX Printer ULA 1026, issue 1, 31 March 1981, Ferranti Archives 2026 (PRN-FER-SCH-106). Source for the pin functions, the A2-only decode, the D1, D2 and D7 write latches, the D0, D6 and D7 read-back, and the BRAKE output.
- ↑ Buffer Micro Shop ZX81 stock list, 2 November 1982, Ferranti Archives 2026 (ZX81-UNK-LIT-121). Source for the £59.95 shop price.
- ↑ Sinclair Research, ZX81 Assembly Instructions (1981), section 9, Ferranti Archives 2026 (ZX81-SIN-LIT-131). Source for the 600 mA and 1.2 A supply figures.
- ↑ 9.0 9.1 9.2 9.3 "ZX Printer Belt" thread, Sinclair ZX World forum, https://www.sinclairzxworld.com/viewtopic.php?p=30496 and https://www.sinclairzxworld.com/viewtopic.php?p=34050 (retrieved 2026-10-18). Source for broken original belts, 3D-printed replacements and their fit, the weak motor and fragile bearings, and the TS 2040 being an Alphacom 32.
- ↑ 10.0 10.1 Ferranti pad-circuit drawing ULA 1026/2, issue 1, 25 May 1981, Ferranti Archives 2026 (PRN-FER-SCH-010). Source for the Schmitt, comparator, tri-state, open-collector, ZAP (600 Ω), MOTOR (150 Ω), BRAKE and FEED/CLEAR (500K) cells.
- ↑ 11.0 11.1 11.2 Ian Logan and Frank O'Hara, The Complete Spectrum ROM Disassembly, the COPY-LINE subroutine at 0EF4, in Richard Dymond's SkoolKit edition, https://skoolkid.github.io/rom/asm/0EF4.html (retrieved 2026-10-18). Source for the meaning of bits 0, 1, 2, 6 and 7 of port FBh.
- ↑ Page 167 of Sinclair's ZX81 manual, chapter 26, with the rear edge-connector pin list, Ferranti Archives 2026 (ZX81-UNK-LIT-137). Source for the signal on each edge contact.
- ↑ "Capacitors For ZX Printer", Retroleum, https://retroleum.co.uk/zx-spectrum-capacitors (retrieved 2026-10-18). A retailer's listing: C2 100 µF 16 V, C3 and C11 10 µF 16 V, C4 100 µF 63 V.
- ↑ 14.0 14.1 14.2 14.3 14.4 "Servicing Your ZX Printer", Your Computer, March 1984. Transcribed at https://k1.spdns.de/Vintage/Sinclair/80/Peripherals/Printers/Sinclair%20ZX%20Printer/Repair/servicing%20zx%20printer.html (retrieved 2026-10-18). Source for the screeching and synchronisation symptoms, the encoder cavity cleaning, the paper feed fix, the paper banding and the lubrication warnings.
- ↑ 15.0 15.1 Fabio Rizzo, "How to rebuild the ZX Printer's belt" (2008; printable version by Ben Versteeg, 2013). Hosted by The Sinclair ZX Archive at https://k1.spdns.de/Vintage/Sinclair/80/Peripherals/Printers/Sinclair%20ZX%20Printer/Repair/How%20to%20rebuild%20a%20ZX%20Printer.pdf (retrieved 2026-10-18).