Recommended Receipt Printer: mC-Print3 Troubleshooting

Use this guide to troubleshoot and resolve problems you may experience with the Star mC-Print3 receipt printer.

• Not printing receipts
  • Troubleshoot the physical connections
  • Troubleshoot the network configuration
  • Troubleshoot the iPad
  • Connect the printer in the Register app settings 
• Frequent disconnections
• Printing long strips of blank paper
• Receipts are blank, discolored, or have gaps
• Cash drawer is not opening automatically
  • Make sure the drawer is unlocked and unobstructed
  • Check the cash drawer cable

Not printing receipts

The lights on the front of your printer turn on or flash in different patterns to tell you about the printer's status and potential problems that can affect printing.

• If the network light is on , the printer is working as expected. Troubleshoot the iPad instead.
• If the network light is off , troubleshoot the physical connections.
• If the network light is flashing , troubleshoot the network configuration.
• For all other light patterns, use the LED Display guide to diagnose the problem and learn how to resolve it.

Troubleshoot the physical connections

1. Make sure the Lightning cable is securely connected to the Lightning port your iPad, and to the iPad 2.4A port on the printer.
2. If you have a label printer or scale at your point of sale and you connected the mC-Print3 to your network:
   • Make sure the Ethernet cable is securely connected to the LAN port on the back of the printer.
   • Make sure the Ethernet cable is also securely to your router, network switch, or wall-mounted Ethernet jack.
   • Make sure the network switch is connected to power, and also to your router via Ethernet cable.
3. Check the full length of the cable(s) for signs of wear or damage, or try a different Lightning or Ethernet cable.
   

   For best results, use a Lightning cable manufactured by Apple. Third-party Lightning cables may not provide a reliable connection or consistent charging.

4. If the problem persists, troubleshoot the iPad.

Troubleshoot the network configuration

Review Set up your network for reliable Register operations and make sure your network setup meets the recommendations.

1. Turn the printer off.
2. Remove the rear cover.
3. With a paper clip or another narrow pointed object, press and hold the RESET button on the back of the printer.
4. While holding RESET, turn the printer back on.
5. Continue holding RESET until the network light flashes .
6. Press and hold the feed button.
   • If the network light stops flashing, set the printer to a static IP address, then reconnect it in the Register app settings. If the problem persists, troubleshoot the iPad. 
   • If the network light keeps flashing, reboot your router and/or network switch (this will temporarily disrupt your connection to the internet and any other receipt printers or label printers on your network), or contact an IT professional for further assistance.

Troubleshoot the iPad

1. From the iPad home screen, select Settings.
2. Scroll down to the Allow Access When Locked section and make sure USB Accessories is toggled on. This helps maintain a stable connection between your printer and iPad.
3. Restart the iPad.
4. Reconnect the printer in the Register app.

Connect the printer in the Register app settings 

1. Sign in to the Register app.
2. Tap the menu icon .
3. Select Settings.
4. Select Receipt Printer.
5. Wait several seconds for the app to search for printers.
6. Tap MCP31L, even if there is already a check mark next to it.
   
7. Select Test Print to confirm the connection. If the printer doesn't respond, force-quit the Register app and try again.

Frequent disconnections

Always use a Lightning cable manufactured by Apple. Third-party Lightning cables may not provide a reliable connection or consistent charging.

If you have a label printer or scale at your point of sale and you connected the mC-Print3 to your network, be sure to enable the printer's SteadyLAN feature.

Review Set up your network for reliable Register operations and make sure your network setup meets the recommendations.

Printing long strips of blank paper

Turn the printer off, wait at least 10 seconds, and then turn the printer back on.

Receipts are blank, discolored, or have gaps

If you're getting blank receipts:

1. Make sure the paper roll is loaded correctly, with the leading end coming off the top of the roll:
   
2. Next, make sure you're using thermal paper.
   • You can check this by scratching the paper with the edge of a coin or another metal object. This should leave a light gray mark on the paper.
   • If there's no mark, replace the paper roll with thermal receipt paper.

If receipts are blackened or discolored, the paper roll may have been exposed to excessive heat.

1. Change to a new roll. 
2. Check for any sources of excessive heat in the immediate area of the printer and whether printer itself may be overheating (see the LED Display guide for more information about heat-related errors).

If there are gaps or white lines on your receipts:

1. Turn the printer off and allow it to cool for several minutes.
2. Carefully clean the thermal print head with isopropyl alcohol and a cotton swab or soft cloth.
   
3. Wait for the alcohol to dry completely before turning the printer back on.

Cash drawer is not opening automatically

Your receipt printer triggers your cash drawer to open automatically each time you complete a sale, even if you don't print a receipt. If your cash drawer is not opening automatically, it could be because your receipt printer is not connected to your iPad. To check this:

1. Sign in to the Register app.
2. Tap the menu icon .
3. Select Settings.
4. Select Receipt Printer.
5. Wait several seconds for the app to search for printers.
6. Tap MCP31L, even if there is already a check mark next to it.
7. Select Test Print.

If MCP31L doesn't appear, or the test print fails, then your cash drawer isn't opening automatically because the Register isn't connected to the printer. Troubleshoot the printer connection.

If the test print is successful, make sure the drawer is unlocked and unobstructed and check the cash drawer cable.

Make sure the drawer is unlocked and unobstructed

1. The key lock on the front of the drawer should be in the vertical (unlocked) position.
2. Turn the key to the left/counterclockwise to open the drawer manually.
3. Remove the till insert and inspect the drawer for foreign objects that could interfere with the mechanism that opens the drawer.

If you no longer have the key, you can order replacements from the manufacturer. You'll need to provide the numerical code engraved on the lock to ensure you get the correct keys.

Check the cash drawer cable

1. Make sure you're using the cable that was included with your cash drawer.
   • This is a specialized CD-101A cable for cash drawers.
   • The connectors on each end are different sizes. 
     • The smaller connector resembles that of a landline phone cable.
     • The wider end resembles that of an Ethernet cable.
     • Neither phone cables nor Ethernet cables will work with your cash drawer.
   • If you don't have the correct cable, order a replacement from the manufacturer.
2. Make sure the narrow end of the cable is securely connected to the Cash Drawer/Buzzer port on the back of the printer.
3. Make sure the wider end is securely connected to the port on the bottom of the cash drawer.