Paper, the obvious one.
Lift the printer cover. Is there paper? Is the roll seated correctly with the thermal side facing the print head? Thermal paper is one-sided — flip the roll if you see no print on a test page. The thermal side is usually the smoother, slightly shinier side.
Thermal paper has a shelf life. A roll that has been sitting in storage for over a year, exposed to heat or sunlight, may print faintly or not at all. If the print is barely visible, change to a fresh roll before troubleshooting further. Spend on quality paper — cheap paper fades and sometimes will not print at all.
Connection, the second obvious one.
USB cable seated firmly at both ends? Power cable connected? Power switch on? Network cable plugged in (for network printers)? Half of all "printer not working" issues are a kicked cable or a power strip that got switched off by a cleaner.
For network printers, check the IP address. The printer should have a fixed IP, not DHCP. If your router rebooted last night and reassigned the IP, the POS will fail to connect until you update the printer settings or reserve the IP on the router.
- USB: cable seated, port works (try a different port)
- Power: cable, switch, surge protector
- Network: IP address fixed, ping reachable
- Bluetooth: paired, in range, battery on the printer
Driver and printer queue.
On Windows, open Devices and Printers, find the printer, check the queue. Stuck print jobs from earlier in the day will block all new prints until cleared. Right-click, See What's Printing, Cancel All Documents. Try printing a test page from the printer properties.
If the test page works but the POS does not print, the issue is between the POS and the driver. Check the POS's printer setting points to the right printer name. Names can change after a driver update, leaving the POS pointing at "Receipt Printer (Old)" while the active printer is "Receipt Printer".
Encoding and character set.
Receipt prints but accented characters or currency symbols come out as boxes or random characters. The printer is set to a different code page than the POS is sending. Most thermal printers support multiple encodings — set both POS and printer to UTF-8 for full Unicode coverage (accents, Asian scripts, modern symbols).
Older printers (pre-2018) often have firmware that does not support full UTF-8. The fix is either a firmware update from the manufacturer or transliterating non-Latin names to Latin script in the database. Test by printing a sample receipt with one of every character you ever expect to print.
Width and template.
Receipt is partially cut off on the right side. Your template is set for 80mm paper and your printer is 58mm (or vice versa). Switch the template width in the POS settings. Most POS systems have separate templates per printer width.
A common error is buying a 58mm printer because it was on sale and using a generic 80mm template. The first three customers will not notice. The fourth will ask why their item name is half-cut. The fifth will be your accountant asking why the tax line is missing. Match width to template.
Cutter and end-of-print.
Receipt prints but does not cut. Or it cuts in the middle of the receipt instead of the end. The cutter command is missing or wrong in the template. ESC/POS commands for cut are well-documented; your template needs a "full cut" or "partial cut" command after the last line of the receipt.
If the cutter physically jams (paper bits stuck), open the printer, lift the cutter assembly, blow out debris with compressed air. Do not use a knife or screwdriver to clear the cutter — you will damage the blade and need a new cutter assembly (A$120-220 for most models).
Intermittent failures.
The printer works fine for an hour, then misses prints for ten minutes, then works again. This pattern is almost always a USB cable that is barely making contact, a power strip that brownouts under load, or a USB hub that throttles bandwidth. Replace the cable first, then the hub if needed.
Network printers have a different intermittent pattern: works fine until the WiFi signal drops, then queues up, then prints a backlog. Move the printer closer to the access point or hardwire it. Receipt printers are not the place to be cute about wireless.
When to call it and replace.
A thermal printer with consistent issues that survive cable swap, paper swap, driver reinstall, and power-strip swap is reaching end of life. Print head wear, cutter blade wear, and main board failures are not worth repairing on a five-year-old printer that costs A$280 new.
Keep a spare printer per branch as an SLA matter. The cost of one weekend without a printer (lost sales, customer complaints, manual receipts) exceeds the cost of a backup unit. Nonari supports drop-in printer swaps with no reconfiguration when the device profile is set to a model family rather than a specific MAC.