Before diving into specific issues:
- Visual Inspection: Check for loose connections, misaligned components, or damaged parts
- Polarity Check: Verify all polarized components
- Power Supply: Confirm correct voltage and polarity
- Connections: Ensure all modules are fully seated
Symptoms: Circuit appears dead, no power indication
Possible Causes:
- Reversed power supply polarity
- Faulty power connection
- Damaged components
- TODO: Additional causes
Solutions:
- Check power supply voltage with multimeter
- Verify polarity of power connections
- Check for short circuits
- TODO: Additional solutions
Safety Note: Always disconnect power before inspecting or modifying circuits.
Symptoms: Power is on (LED lit) but no sound from speaker
Possible Causes:
- Speaker not connected or faulty
- Speaker connector (SPK) not fully seated
- Volume potentiometer at minimum
- No FM signal being received (no stations)
- Audio output circuit failure
Solutions:
- Verify speaker is connected to SPK connector and fully seated
- Check speaker polarity (if applicable)
- Rotate volume potentiometer clockwise to increase volume
- Try tuning to a known strong FM station
- Test speaker with another audio source to verify it works
- Measure voltage at speaker connector (should vary with audio signal)
- Check for loose SPK connector on board
Testing: Connect speaker to known working audio source. If speaker works, issue is with radio board.
Symptoms: Radio works but reception is weak, noisy, or no stations found
Possible Causes:
- Inadequate or missing antenna
- Antenna not properly connected
- Board located near interference sources
- Tuning potentiometer not adjusted correctly
- Weak signal area
- FM radio IC malfunction
Solutions:
- Verify antenna is connected (if applicable)
- Try different antenna lengths (optimal for FM: TODO cm)
- Move board away from:
- Computer monitors and screens
- Power supplies and transformers
- LED lights and dimmers
- USB cables
- Slowly rotate tuning potentiometer through full range
- Try reception in different locations (near window, higher elevation)
- Use longer or external antenna for better reception
- In very weak signal areas, consider external powered antenna
Note: FM reception is highly dependent on location and antenna quality.
Symptoms: Audio output is distorted, unclear, or has excessive static
Possible Causes:
- Volume set too high
- Speaker impedance mismatch
- Poor FM signal strength
- Power supply voltage too low or unstable
- Damaged speaker
- Interference from nearby devices
Solutions:
- Reduce volume using volume potentiometer
- Verify speaker impedance matches board specifications (TODO ohms)
- Improve FM signal reception (see "Poor Reception" above)
- Check power supply voltage with multimeter (should be TODO V)
- Try different speaker to rule out speaker damage
- Move board away from interference sources
- Ensure power supply can provide adequate current (TODO mA)
Symptoms: Volume or tuning potentiometers have no effect
Possible Causes:
- Potentiometer reached end of rotation
- Mechanical binding or damage
- Internal potentiometer failure (rare on new boards)
Solutions:
- Volume: Verify rotating clockwise increases volume, counterclockwise decreases
- Tuning: Slowly rotate through entire range while monitoring for station changes
- Check for any physical obstruction preventing rotation
- Try gentle adjustment - don't force rotation beyond stops
- If potentiometer feels loose or doesn't rotate smoothly, contact support
Symptoms: Radio works but status LED (D2) doesn't light
Possible Causes:
- LED installed backwards (unlikely on pre-assembled board)
- LED burned out
- Current limiting resistor failure
- Insufficient power supply voltage
Solutions:
- Verify power supply provides correct voltage
- Check voltage across LED terminals with multimeter
- LED failure doesn't affect radio operation - cosmetic issue only
- Contact support if LED is important for your application
Voltage Measurements:
- Power Input: Measure at power connector - should read TODO V DC
- Board Power: Measure at convenient test points - should read TODO V
- Speaker Output: AC voltage that varies with audio signal
Continuity Testing:
- Power OFF and disconnected
- Test continuity of speaker wires
- Verify ground connections
Connector Testing:
- Check JST connectors are fully inserted (should click)
- Gently tug connectors to verify they're locked
- Inspect connector pins for damage or debris
WARNING: Some circuits require speaker load. Check specifications before operating without speaker connected.
- If safe to operate without speaker, can test for audio output with multimeter
- Set multimeter to AC voltage
- Measure at SPK connector
- Should see varying AC voltage when tuned to station
Verify board orientation by checking:
- QR code (QR1) position
- Component labels readable
- Connector labels match expected positions
Board Connectors:
- SPK: Speaker output
- Power connectors: JST connectors on board edges
Board Components:
- D2: Status LED (red)
- POT1/POT2: Potentiometers (volume and tuning)
- U1: FM radio IC
- QR1: Documentation QR code
If you've tried these troubleshooting steps and still need help:
- Review the Assembly Instructions to ensure proper construction
- Check the Bill of Materials for correct component values
- Visit the Support section for additional help
Last Updated: TODO
Revision: See Revision Notes