1. Introduction
The Hytech S-link SL-BT235 is a versatile Bluetooth FM Transmitter designed for in-car use. It allows you to stream audio from your Bluetooth-enabled devices, play music from USB drives or TF cards, and charge your mobile devices via its dual USB ports, including a Quick Charge 3.0 port. This manual provides detailed instructions for setting up, operating, and maintaining your device.
Image 1.1: Angled view of the Hytech S-link SL-BT235 Bluetooth FM Transmitter, showing the LED display and control buttons.
2. Package Contents
- Hytech S-link SL-BT235 Bluetooth FM Transmitter
- User Manual
3. Product Overview
Familiarize yourself with the components of your FM transmitter:
Image 3.1: Front view of the transmitter, highlighting the LED display, USB ports, and main control area.
Image 3.2: Top-down view of the transmitter, showing the multi-function knob and additional buttons.
- LED Display: Shows FM frequency, volume, and other status information.
- Multi-function Knob: Rotate to adjust volume or FM frequency. Press to play/pause music or answer/end calls.
- Previous Track / Mode Button (M): Short press for previous track. Long press to switch audio input mode (Bluetooth/USB/TF Card).
- Next Track / FM Frequency Adjustment Button (FM): Short press for next track. Long press to enter FM frequency adjustment mode.
- EQ Button: Press to cycle through equalizer presets.
- Light Button: Press to change or turn off the LED ambient light.
- QC 3.0 USB Charging Port: Provides fast charging for compatible devices.
- 5V/2.4A USB Charging Port: Standard USB charging port.
- TF Card Slot: Insert a TF (microSD) card for music playback (location not visible in images, typically on the side).
4. Setup
- Insert into Car Cigarette Lighter: Plug the FM transmitter into your vehicle's 12V/24V cigarette lighter socket. The device will power on automatically, and the LED display will illuminate.
- Set FM Frequency:
- Tune your car radio to an unused FM frequency (one with no static or strong broadcast).
- On the transmitter, long press the 'FM' button until the frequency on the LED display starts flashing.
- Rotate the multi-function knob left or right to match the transmitter's frequency to your car radio's frequency.
- Once matched, wait a few seconds for the frequency to stop flashing, or short press the multi-function knob to confirm.
5. Operating Instructions
5.1. Bluetooth Pairing
- After setting the FM frequency, the transmitter will automatically enter Bluetooth pairing mode. The LED display will show 'bt'.
- Enable Bluetooth on your mobile device and search for available devices.
- Select 'SL-BT235' from the list to connect. Once paired, the transmitter will announce 'Bluetooth Connected', and you can now stream audio.
- The device will automatically connect to the last paired device when powered on, if Bluetooth is enabled on your phone.
5.2. Music Playback
- From Bluetooth: Once paired, play music on your phone. Audio will transmit to your car stereo.
- From USB Drive: Insert a USB flash drive (up to 32GB, FAT32 format) containing MP3/WMA/WAV/FLAC files into the 5V/2.4A USB port. The device will automatically switch to USB mode and begin playing.
- From TF Card: Insert a TF (microSD) card (up to 32GB, FAT32 format) containing MP3/WMA/WAV/FLAC files into the TF card slot. The device will automatically switch to TF card mode and begin playing.
- Switching Modes: Long press the 'M' (Previous Track/Mode) button to cycle between Bluetooth, USB, and TF card playback modes.
Music Controls:
- Play/Pause: Short press the multi-function knob.
- Next Track: Short press the 'FM' button.
- Previous Track: Short press the 'M' button.
- Volume Adjustment: Rotate the multi-function knob.
5.3. Hands-Free Calling
- Answer Call: Short press the multi-function knob when an incoming call rings.
- End Call: Short press the multi-function knob during a call.
- Reject Call: Long press the multi-function knob when an incoming call rings.
- Redial Last Number: Double press the multi-function knob.
5.4. Charging Devices
- QC 3.0 Port: Connect your Quick Charge compatible device to the QC 3.0 USB port for rapid charging.
- 5V/2.4A Port: Connect other devices to the 5V/2.4A USB port for standard charging.
5.5. EQ Settings
- Press the 'EQ' button to cycle through available equalizer sound presets (e.g., Normal, Pop, Rock, Jazz, Classical).
5.6. LED Ambient Light
- Press the 'Light' button (bulb icon) to change the color of the LED ambient light or to turn it off.
6. Maintenance
- Keep the device dry. Moisture can damage electronic circuits.
- Do not expose the device to extreme temperatures. High temperatures can shorten the life of electronic devices and warp plastic parts.
- Do not use harsh chemicals, cleaning solvents, or strong detergents to clean the device. Wipe it with a soft, dry cloth.
- Avoid dropping or subjecting the device to strong impacts.
7. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No power | Loose connection; Car cigarette lighter socket not working. | Ensure the transmitter is firmly plugged in. Check if the car's cigarette lighter socket is functional. |
| Static or poor audio quality | FM frequency interference; Transmitter/radio frequency mismatch. | Find a clearer, unused FM frequency on your car radio and match the transmitter to it. Avoid frequencies with strong local radio stations. |
| Bluetooth not connecting | Bluetooth not enabled on phone; Device not in pairing mode; Already connected to another device. | Ensure Bluetooth is on your phone. Restart the transmitter. Forget 'SL-BT235' from your phone's Bluetooth list and re-pair. |
| USB/TF card not playing | Incorrect file format; Card/drive not recognized; Device in wrong mode. | Ensure music files are MP3/WMA/WAV/FLAC. Check if the USB drive/TF card is formatted to FAT32. Long press 'M' to switch to USB/TF card mode. |
| Slow charging | Device not QC compatible; Cable issue. | Ensure your device supports Quick Charge 3.0 for the QC port. Use a high-quality charging cable. |
8. Specifications
| Model: | SL-BT235 |
| Bluetooth Version: | V5.0 |
| Input Voltage: | 12V-24V |
| FM Frequency Range: | 87.5-108.0 MHz |
| USB Output 1 (QC3.0): | 5V/3A, 9V/2A, 12V/1.5A (Max 18W) |
| USB Output 2: | 5V/2.4A |
| Music Format Support: | MP3, WMA, WAV, FLAC |
| USB/TF Card Capacity: | Up to 32GB (FAT32 format) |
| Product Weight: | 0.1 Kilogram |
9. Warranty and Support
This Hytech S-link SL-BT235 Bluetooth FM Transmitter comes with a 2-year warranty from the date of purchase. This warranty covers manufacturing defects and material faults under normal use.
The warranty does not cover damage caused by misuse, accident, unauthorized modification, or improper installation. Please retain your proof of purchase for warranty claims.
For technical support or warranty inquiries, please contact your retailer or the official Hytech customer service channels. Refer to the product packaging or the manufacturer's website for specific contact information.