Atari XMM801 Maintenance Guide

The Atari XMM801 needs a clean paper path, a fresh ribbon cartridge and, after any work on the mechanism, a check of a handful of adjustments. Atari's owner's manual covers the care an owner can do, and the eight-page mechanism section at the back of the XMM801 Field Service Manual (CO 70435) gives the adjustments, gauges and grease.^[1]^[2] Faults are diagnosed on the Atari XMM801 Troubleshooting page.

Precautions

The owner's manual gives these rules for the printer:^[1]

Do not print without paper and a ribbon cartridge fitted.
Wait at least two seconds after switching off before switching on again, or the printer may not initialise properly.
Do not touch the top of the print head after printing; it gets hot. The head carries a "hot surface" caution label.
Do not move the print head by hand. The field service manual's own dot strobe test moves the head by hand, and limits that to a few seconds.^[2]
Keep the printer on a firm, level surface, out of direct sunlight and high humidity. Operate it between 5 and 35 °C and store it between −30 and 70 °C.

Unpacking and moving

New printers were shipped with tape and foam packing on the print head and two shipping screws in the bottom panel. Remove the top cover and the packing from the head, then stand the printer on its back panel and take out the two screws before switching on for the first time.^[1] The parts list identifies the shipping screws as black M4 × 15 screws, and the packing set includes a head fixer.^[2] For shipping or storage, Atari's advice is to repack the printer in its original factory packing.^[1]

Cleaning

Keep the top cover on, both when printing and in storage, to keep dust out of the print head and carriage area.^[1]
Clean the platen and the paper bail rollers with a cotton ball and a little rubbing alcohol, turning the platen knob as you go.^[1]
Do not touch the carriage rod. Finger oil attracts dust, which can affect the carriage's movement.^[1]
If anything falls into the head and carriage rod area, switch off at once and remove it.^[1]
Clean the outside with a soft, damp cloth only; household cleaners and abrasives can damage the case.^[1]

The field service manual lists alcohol as the general cleaning material for work on the mechanism.^[2]

Ribbon

The ribbon is a cartridge with a multistrike carbon-film ribbon.^[1] To fit one, switch off and remove the top cover, turn the cartridge knob anticlockwise to take up slack, lower the cartridge in bottom first so that its two guide tabs drop into their slots, and press it down until it snaps in. Slip the exposed ribbon between the print head and the metal ribbon mask against the platen, and take up the slack again. To remove it, lift the top of the cartridge until the tabs are free, then lift it out.^[1]

The printer has no ribbon sensor. Light print means the ribbon is used up, and a cartridge that does not advance unused ribbon has been fitted wrongly.^[1] The parts list gives the cartridge as IK-SP80RC.^[2] Best Electronics sells the black XMM801/SMM804 cartridge as Atari part CO70263.^[3] Antic found Commodore 1526 and Mannesmann Tally Spirit 80 ribbons interchangeable with it, and printed its review samples with a Pelikan P-116.^[4]

Paper

The XMM801 takes fanfold pin-feed paper on its sprockets, or single sheets by friction like a typewriter.^[1]

For pin-feed paper, fit the wire paper separator, unlock the sprockets, feed the paper through the separator's entry slot to the sprockets, close the sprocket clamps and lock the sprockets. Set the paper-release lever to its friction position only while loading, then return it to the pin-feed position marked by the arrow on the lever.^[1]
For single sheets, slide the sprockets fully out to the sides and lock them, set the paper-release lever to friction and feed the sheet behind the platen with the platen knob.^[1]
Do not use friction feed with pin-feed paper; the manual says it will jam.^[1]
Do not let printed paper pile up on the paper going in. If it is pulled back into the printer it jams the paper feed and can damage the printer.^[1]

Mechanism adjustments

The field service manual calls for these materials and tools: Beacon 325 grease, Loctite on adjusted screws, alcohol for cleaning, a 15-17 W soldering iron, small and medium cross-head screwdrivers, feeler gauges and a 0-500 g tension gauge.^[2]

**XMM801 mechanism adjustments (FSM, mechanism section pp. 2-7)**
Adjustment	Specification	Method
Print head gap	0.35 mm between the ribbon guide and the head nose	Loosen the two M3 head screws, hold a 0.35 mm feeler gauge in the gap and tighten them. The gauge should then slide in smoothly.
Synchronous (toothed) belt tension	250-300 g	Move the head to the right-hand end and loosen the three M2.5 × 6 screws of the ribbon gear assembly. Press the middle of the belt with the tension gauge until it just touches the other run of the belt, move the ribbon gear assembly until the reading is in range, and tighten the screws.
Carriage motor mesh	Backlash between the motor pinion and the right pulley as small as possible, with the head still moving smoothly	Set the motor position on its M3 × 6 screws while jogging the head sideways, tighten them and recheck.
Home position	Left edge of the printed characters 25.6 ± 0.5 mm from the left edge of 10-inch paper	Loosen the M2.5 × 6 screw of the home position switch, move the switch, print again and recheck.
Paper end sensor	0.05-0.15 mm between the P-G lever and the tip of the leaf switch, with the lever held against the platen; contact gap more than 0.5 mm with paper loaded	Move the leaf switch assembly and tighten its screw.

The gauge table at the start of the mechanism section lists a 0.5 mm gauge for the head gap, but the head adjustment procedure itself uses 0.35 mm.^[2]

Lubrication

The field service manual specifies Beacon 325 grease in two places:^[2]

The meshing parts of the ribbon gear assembly, greased before the assembly goes back on the chassis. Check afterwards that the gears turn smoothly and run true.
The pinion of the carriage motor and the upper gear of the right pulley.

Replacing parts of the mechanism

Atari's service policy was to replace the print head on its own. For any other fault in the mechanism, the field engineer fitted a complete new mechanism unit and sent the faulty one back to the factory.^[2] The mechanism section covers these parts:^[2]

Print head: remove the two M3 head screws and unplug the flexible cable, then set the head gap after refitting.
Ribbon gear assembly: three M2.5 × 6 screws and the synchronous belt; leave the screws slightly loose and set the belt tension.
Carriage motor: unplug CON6 and CON8 from the main board and remove the M3 × 6 screws; set the gear mesh after refitting.
Home position switch: one M2.5 × 6 screw; the leads are soldered to the switch.
Paper end sensor: the leaf switch comes out with the P-G lever; the leads are soldered.
Head flexible cable (FPC): unplug it from the head, remove two M2.5 × 6 screws from the head holder and unsolder the cable from the connection board.

For electrical checks with the mechanism out of the bottom case, the negative terminal of the bridge rectifier BD1 makes a convenient ground point.^[2]

Fuse

The mains fuse F1 is on the filter board. Replace it with the rating for the printer's mains version: 1.0 A on the 100 V and 115 V models, T 400 mA (time-lag) on the 220 V and 240 V models.^[2]

Capacitors

The main board has eight aluminium electrolytic capacitors, including the 2,200 µF and 3,300 µF reservoirs of the two supplies. They are listed on the Atari XMM801 Capacitor Replacement Guide.^[2]

Related pages

References

↑ ^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 ^1.16 Atari Corp., Atari XMM801 Dot-Matrix Graphics Printer Owner's Manual, C025959-001 Rev. A, 1985: unpacking (p. 1), connecting and ribbon (pp. 2-4), loading paper (pp. 4-7), self test (p. 9), troubleshooting and preventive maintenance (pp. 55-57). Hosted here as File:Atari XMM801 Owner's Manual C025959-001.pdf.
↑ ^2.00 ^2.01 ^2.02 ^2.03 ^2.04 ^2.05 ^2.06 ^2.07 ^2.08 ^2.09 ^2.10 ^2.11 ^2.12 Atari Corp., XMM801 Field Service Manual, CO 70435, October 1985: printer mechanism (p. 3), power supply fuses (p. 8), check point notes (pp. 19 and 21), parts list (pp. 27-40), exploded views (pp. 41-43), and the separately numbered "Services for printer mechanism" (pp. 1-8). Hosted here as File:Atari XMM801 Field Service Manual C070435.pdf.
↑ Best Electronics, "Atari 8 bit Printer Supplies". best-electronics-ca.com, retrieved 6 October 2026. Supplier listing: XMM801/SMM804 multistrike black ribbon cartridge CO70263.
↑ Gregg Pearlman, "Two New Atari Printers", Antic vol. 5 no. 8, December 1986. atarimagazines.com. Ribbon cartridge, compatible ribbons and the Pelikan P-116.

[om-1] 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 ^1.16 Atari Corp., Atari XMM801 Dot-Matrix Graphics Printer Owner's Manual, C025959-001 Rev. A, 1985: unpacking (p. 1), connecting and ribbon (pp. 2-4), loading paper (pp. 4-7), self test (p. 9), troubleshooting and preventive maintenance (pp. 55-57). Hosted here as File:Atari XMM801 Owner's Manual C025959-001.pdf.

[fsm-2] 2.00 ^2.01 ^2.02 ^2.03 ^2.04 ^2.05 ^2.06 ^2.07 ^2.08 ^2.09 ^2.10 ^2.11 ^2.12 Atari Corp., XMM801 Field Service Manual, CO 70435, October 1985: printer mechanism (p. 3), power supply fuses (p. 8), check point notes (pp. 19 and 21), parts list (pp. 27-40), exploded views (pp. 41-43), and the separately numbered "Services for printer mechanism" (pp. 1-8). Hosted here as File:Atari XMM801 Field Service Manual C070435.pdf.

[best-3] Best Electronics, "Atari 8 bit Printer Supplies". best-electronics-ca.com, retrieved 6 October 2026. Supplier listing: XMM801/SMM804 multistrike black ribbon cartridge CO70263.

[antic-4] Gregg Pearlman, "Two New Atari Printers", Antic vol. 5 no. 8, December 1986. atarimagazines.com. Ribbon cartridge, compatible ribbons and the Pelikan P-116.

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