21475154 - Sheet, Linear Scale SJ-640 (encoder strip)

Linear encoder strip – Roland SJ-640 – 21475154

The Roland 21475154 linear encoder tape (Sheet, Linear Scale SJ-640) is the optical ruler fitted along the carriage rail of the SJ-640 and SJ-645EX models. The encoder sensor continuously reads it to determine the exact position of the print heads.

Its 180 lines per inch (180 LPI) graduations provide the controller with a positional reference on every pass. This precision ensures accurate drop placement and bidirectional printing without misalignment.

Supplied on its own, in the original dimensions of 2365 × 15 mm, including mounting holes. Three options are available on this product page: New (genuine Roland part), Refurbished (inspected genuine part) or New / Compatible (strip manufactured by DG Spare Parts).

Technical specifications

• OEM part number: 21475154
• Manufacturer: Roland DG
• Part type: Linear encoder scale (linear encoder strip)
• Resolution: 180 LPI
• Dimensions: 2365 mm × 15 mm (total length, including holes)
• Axis concerned: Print carriage movement
• Delivery: Single part, ready for installation
• Condition: New (OEM), Refurbished or New / Compatible depending on the variant chosen

Compatibility and use

• Roland SJ-640
• Roland SJ-645EX

‘New / Compatible’ version – manufactured by DG Spare Parts

• Strip cut in our workshop from a generic 180 LPI encoder strip, 15 mm wide, to the original length of 2365 mm.
• Mounting holes drilled by DG Spare Parts using the original template: the strip is supplied ready for fitting.
• Same resolution and width as the original part, compatible with the existing encoder sensor.
• Made to order; not covered by the Roland manufacturer’s warranty.

Function

• To provide the encoder sensor with the carriage’s position reference
• Ensure synchronisation between the carriage’s movement and the heads’ firing
• Ensure alignment of the forward and return passes
• Maintain the dimensional accuracy of the prints

Possible symptoms of wear

• ‘Motor error’ or carriage stoppage during printing
• Misalignment or duplication of passes in bidirectional mode
• Fine, irregular stripes across the width of the media
• Scratches, ink marks or faded graduations visible on the tape

Replacing the encoder belt restores reliable carriage positioning and eliminates registration errors caused by impaired reading.

♻️ DG Spare Parts – European specialist in spare parts for large-format printers and plotters.

SP-FP-v1.4.0-20260930