⚠️ IMPORTANT: Both the paper‑size setting in App AND the adjustable paper guide (side sliders) must match your actual paper. Mismatch will cause skewed printing, paper jams and device errors.
JD‑166 supports A4 (210 mm × 297 mm) and US Letter (216 mm × 279 mm) paper sizes. The App will auto‑select default paper size based on your region during first‑time setup: US defaults to US Letter; Europe defaults to A4.
Common issue scenario: If you use A4 paper while the App is still set to US Letter (or vice‑versa), the paper will shift inside the printer and lead to feeding faults.
Please troubleshoot step‑by‑step:
- Adjust physical paper guide Load paper into the feeder. Slide the two side paper guides until they gently touch paper edges.
Do NOT set them too tight (blocks paper feeding) nor too loose (paper shakes and skews).
- Check App paper‑size setting Confirm the paper‑size option inside the App matches the real paper you load. Change it manually if auto‑default does not fit your paper.
- Verify paper type Make sure you are using supported thermal paper within the printer’s size range.
- Reboot printer Restart your printer if the above steps do not resolve the problem.
Note: A4 is 6 mm narrower and 18 mm shorter than US Letter. You need to readjust both paper guides and App setting when switching between these two paper sizes.