1. Introduction
Thank you for choosing the Callstel TD-120.app Connected Thermal Printer. This compact and portable mini printer allows you to print photos, labels, drawings, and receipts directly from your smartphone or tablet via Bluetooth. Utilizing thermal printing technology, it requires no ink cartridges, offering a clean and convenient printing experience. This manual provides detailed instructions for setup, operation, maintenance, and troubleshooting to ensure optimal performance of your device.
2. Safety Instructions
- Do not disassemble, repair, or modify the printer yourself.
- Keep the printer away from water, moisture, and high temperatures.
- Use only the specified thermal paper rolls.
- Avoid exposing the printer to direct sunlight for extended periods.
- Keep out of reach of children.
- Charge the printer using a standard USB power adapter (not supplied) and the provided USB-C cable.
3. Package Contents
Please check the package for the following items:
- Callstel TD-120.app Thermal Printer
- USB Charging Cable (USB-A to USB-C)
- BPA-free Thermal Paper Roll (one pre-installed or included)
- User Manual (this document)
4. Product Overview

Figure 4.1: Printer with a sample print and smartphone showing the app interface.

Figure 4.2: Key features of the printer, including BPA-free paper, 200 dpi resolution, and Bluetooth 5.1 connectivity.

Figure 4.3: Side view of the printer, illustrating the USB-C charging port.
The Callstel TD-120.app printer features a power button, a status indicator light, and a paper output slot. The USB-C port for charging is located on the side. The internal compartment houses the thermal paper roll.
5. Setup
5.1 Initial Charging
- Connect the provided USB-A to USB-C charging cable to the printer's USB-C port.
- Plug the USB-A end into a standard USB power adapter (e.g., smartphone charger, computer USB port).
- The status indicator light will show charging status (e.g., red for charging, green for fully charged). Charge the printer fully before first use.
5.2 Loading Thermal Paper

Figure 5.1: Printer with the paper compartment open, showing how to insert the thermal paper roll.
- Gently open the printer's top cover by sliding or lifting the designated latch.
- Insert the thermal paper roll into the compartment, ensuring the paper feeds from the bottom and the leading edge is straight.
- Pull a small length of paper out of the slot, ensuring it is aligned.
- Close the top cover firmly until it clicks into place.
5.3 App Installation

Figure 5.2: Screenshots of the 'Fun Print' mobile application, showing various printing options.
- Search for the "Fun Print" application in your device's app store (Google Play Store for Android or Apple App Store for iOS).
- Download and install the application.
- Grant necessary permissions when prompted by the app.
6. Operating Instructions
6.1 Connecting via Bluetooth
- Ensure the printer is powered on. The status indicator light should be active.
- Enable Bluetooth on your smartphone or tablet.
- Open the "Fun Print" application.
- Within the app, navigate to the device connection section (usually indicated by a Bluetooth icon or 'Connect Device').
- Select your printer from the list of available Bluetooth devices (it may appear as "TD-120" or a similar name).
- Once connected, the app will indicate a successful connection, and the printer's status light may change.
6.2 Printing from the App
The "Fun Print" app offers various printing functions:
- Image Printing: Select an image from your gallery, edit it if desired (crop, filters), and tap the print button.
- Text Printing: Type or paste text into the app's text editor and print.
- Label Printing: Use pre-designed templates or create custom labels.
- Webpage Printing: Some versions of the app may allow printing content directly from web pages.
- DIY Content: Explore features for creating drawings, notes, or to-do lists.
After selecting your content and confirming print settings within the app, tap the print icon to send the job to the printer.
7. Maintenance
7.1 Cleaning the Printer
- Ensure the printer is turned off and disconnected from power before cleaning.
- Wipe the exterior of the printer with a soft, dry cloth.
- If necessary, use a slightly damp cloth (water only) and then immediately dry.
- Do not use abrasive cleaners, solvents, or alcohol, as these can damage the printer's surface.
- Periodically clean the print head with a cotton swab lightly dampened with isopropyl alcohol, allowing it to dry completely before use.
7.2 Replacing Thermal Paper
Follow the steps outlined in Section 5.2 "Loading Thermal Paper" to replace an empty paper roll with a new one. Ensure the new roll is 57 mm wide and up to 30 mm in diameter.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Printer does not turn on | Low battery; Power button not pressed correctly | Charge the printer fully; Press and hold the power button for a few seconds. |
| Cannot connect via Bluetooth | Bluetooth off on device; Printer not in pairing mode; Out of range; Interference | Ensure Bluetooth is enabled; Restart printer and app; Move closer to printer; Avoid other wireless devices. |
| Poor print quality / Blank prints | Incorrect paper loading; Low battery; Print head dirty; Faulty paper | Re-insert paper correctly (thermal side facing print head); Charge printer; Clean print head (see Maintenance); Try a new roll of thermal paper. |
| Paper jam | Paper not loaded straight; Damaged paper roll | Turn off printer, gently open cover and remove jammed paper; Re-load paper correctly; Replace paper roll if damaged. |
| App crashes or freezes | App bug; Device memory issues | Close and restart the app; Clear app cache; Reinstall the app; Ensure your device has enough free memory. |
9. Specifications
| Feature | Detail |
|---|---|
| Model Name | TD-120.app |
| Model Number | ZX7597-944 |
| Printing Technology | Thermal |
| Printer Output | Monochrome (Black & White) |
| Max Print Resolution | 200 dpi |
| Connectivity Technology | Bluetooth 5.1 |
| Compatible Devices | Smartphone, Tablet PC (Android, iOS) |
| Max Media Size | 57 mm wide, up to 30 mm diameter roll |
| Power Supply | 1200 mAh Lithium-ion Battery |
| Charging Interface | USB-C |
| Item Weight | 150 g |
| Dimensions | 81 x 81 x 40 mm |
| Special Feature | Portable, BPA-free thermal paper |
10. Warranty and Support
For warranty information and technical support, please refer to the documentation provided at the time of purchase or contact your retailer. You may also visit the official Callstel website for further assistance and updated information.
