How I Repaired a VON Woofer With No Bass
A client brought in a VON woofer with “No Bass” symptoms, I did initial tests to confirm what the customer said and indeed there was no Bass.
I opened the woofer and went straight to the bass circuit.
This woofer had a separate small board dedicated to the low-pass filter, this board is critical — if it fails, you lose bass completely
I did voltage testing around this and found 33V dc on one side of the resistor and less than 1 volt dc on the other side.
This is a red flag. A proper audio circuit should not have such a drastic voltage drop unless there is a faulty component or open path
I lifted one leg of the resistor and testing its resistance and found it very high. The resistor color code was red, purple, red (2700 ohms (2.7 kΩ).
Check Out The 2nd Edition Of Woofer Repair Course By Humphrey
I did not have the exact resistor in my kit and therefore I used two resistors in series (2400 ohms and 300 ohms)
After replacing the resistor, I re-tested the voltage and found the 1 volt has increased to 12 volts.
I connected the board back and tested the machine, to my surprise the woofer came back to life with deep, clean bass!
Key Lesson for Technicians
If you ever encounter: Woofer ON but no bass, Mid/high sound present and No distortion
Always check: Low-pass filter circuit, feeding resistors, Signal path continuity and Voltage drops across stages.
Humphrey Kimathi is from Nairobi Kenya and the author of:
1) Washing Machine Repair Made Simple
4) Lcd-Led Television Repair Guide
5) LCD-LED Television Repair Cases/Tips Volume 02
6) Microwave Oven Repair Made Easy
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Note: You may check out his previous post on Pev Pro KV-80, 8-Channel Mixer Repaired After Catastrophic Failure!
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Parasuraman S
June 6, 2026 at 3:03 pm
Excellent professional fix! Many thanks for sharing!
Humphrey Kimathi
June 10, 2026 at 5:59 pm
Thank you so much! I really appreciate your kind words.
Regards
Albert van Bemmelen
June 6, 2026 at 5:45 pm
Amazing that you managed to pinpoint the failure to a single resistor on that small bass driving board Humphrey!
From your 'to my surprise the woofer came back to life' in your conclusion, I understand that you had to find the cause without any supporting schematics or additional guide. Which made it a very professional fix indeed!
Humphrey Kimathi
June 10, 2026 at 6:02 pm
Thank you so much for your kind and thoughtful feedback—I truly appreciate it.
You’re absolutely right, there was no schematic available for this model, so the repair relied heavily on signal tracing and understanding how the low-pass filter stage should behave. That small resistor turned out to be the key fault, even though it’s easy to overlook such components.
Thanks again for your encouragement.
Yogesh Panchal
June 6, 2026 at 7:15 pm
Good Fix! Sir
Humphrey Kimathi
June 10, 2026 at 6:04 pm
Thank you very much, Sir—I truly appreciate your feedback!
Glad you found the repair helpful.
Mark J
June 7, 2026 at 2:49 am
Humphrey good article very informative. Thank you for sharing.
Humphrey Kimathi
June 10, 2026 at 6:06 pm
Thank you so much, I truly appreciate your kind words!
I’m glad you found the article informative. Sharing practical repair experiences like this is always my goal, especially when it can help others in troubleshooting similar issues.
Thanks again for your encouragement!
Imoud.O
June 7, 2026 at 3:48 am
Thanks friend
Humphrey Kimathi
June 10, 2026 at 6:07 pm
You’re most welcome, my friend! Thanks again for your support.
Philip
June 7, 2026 at 5:52 pm
Quite a helpful tuition. If you have such like woofer, visitors dont leave your premise in a hurry when good music is playing, bass is more than needed at the correct volume. I was surprised one day to find double TEA2025B ICs in a sub-woofer.
Humphrey Kimathi
June 10, 2026 at 6:09 pm
Thank you for your insightful comment—I appreciate it!
You’re absolutely right, good bass really transforms the listening experience. When the low-frequency section is working properly, it makes a big difference in how long people enjoy the sound.
And yes, the use of dual TEA2025B ICs in some sub-woofers can be surprising! They are often configured to increase output power or drive multiple channels, especially in compact designs.
Thanks again for sharing your experience—great input!