Before opening your subwoofer, unplug it from the power outlet. Electrolytic capacitors can store charge even when the device is turned off. Work carefully and avoid accidental short circuits.
Diagnosing the Hum
- 0:04 ► Testing subwoofer buzzing.
- 0:16 ► Disassemble the subwoofer. The amplifier board is usually attached to the rear panel. Unscrew it and gently disconnect any cables.
- 2:02 ► Unboxing capacitors.
- 5:05 ► Inspect the circuit board. Look for capacitors that are bulging, leaking, or discolored — these are common signs of failure.
- Test with a multimeter. If the capacitors look fine, check them using a multimeter with capacitance mode or an ESR (Equivalent Series Resistance) tester. Faulty capacitors often show reduced or no capacitance.
- 5:30 ► Testing a subwoofer after repair.
What you will need:
Screwdriver.
Soldering iron (30-60 W).
Tin and flux.
Solder sucker or braid.
Multimeter.
A new capacitor of the same capacity and voltage (or with a small voltage reserve).
- Note the specifications. Printed on the capacitor, you’ll find something like
3300μF 25V. Match the capacitance exactly, and use equal or higher voltage (but never lower). I bought the capacitors here - Desolder the old capacitor. Use a soldering iron and a desoldering pump or copper braid to remove the old part.
- Install the new capacitor. Observe polarity: the negative leg is usually shorter and marked on the body. The circuit board should also indicate polarity. Solder cleanly and securely.
Reassembly and Testing
Once the new capacitor is installed:
- Reassemble the subwoofer.
- Plug it back in and reconnect the speaker.
- Turn it on – if the hum is gone, you’ve successfully repaired it!
What If the Hum Persists?
If the humming noise remains after replacing the capacitor, other issues might be at play, such as:
- Bad grounding
- Faulty power supply
- Defective amplifier IC
Still, in many cases, a simple capacitor swap solves the problem.
Subwoofer hums – Easy repair Subwoofer – Fixing Subwoofer Buzz
Leave a Reply