VON 2.1 Channel woofer works a few minutes then stops

 A customer called me concerning a woofer that she wanted checked by a technician. She told me that the woofer was dead. I was in a hurry, so I did not have time to confirm the customer's complaint, which is very important.

 I picked up the woofer on my way to my shop. upon reaching my shop, I applied the power, and the woofer was up and running. So I just kept it aside to do other things.

Later, I called her and told her the woofer is working, she then told me that it stops working after a few minutes.

From experience, I know that these symptoms are usually caused by failed capacitors, so my first assignment was to check all capacitors using an ESR meter.

To my surprise, there was no culprit, and all capacitors were found okay.

I decided to use the next card I use in troubleshooting woofers by using touch.

So I powered the woofer and placed my fingers on the audio ics, and whichever is getting very hot is usually the culprit.

Using the above method, I found the IC below TDA 2030 marked with X was getting too hot for my fingers and hence decided to replace it directly.

 After replacing it, I did the touch test again and noted the ic was still getting very hot, I guesed maybe there was a capacitor I never picked and I decided to re-check all the capacitors around that ic which are very few and all of the passed the test with flying colors, so what next.

I kept the woofer aside, very frustrated man, later I decided to check for dry joints on the entire board using a magnifying glass, and to my supprise I noted a capacitor on pin1 of TDA 2030, which was getting hot, has a serious dry joint which could not have been picked using naked eyes.

I re-soldered the capacitor and tested the woofer and noted the ic is no longer getting hot.

Later, I decided to do a postmortem of what caused the IC 2030 to overheat.

So I decided to get the circuit diagram of IC TDA2030, and this is what I got. Pin1 is the input signal, and capacitor C1 is used to block  DC and pass the AC signal. Since the capacitor had dry joints, this led to a poor signal to the IC and hence overheating.

I tested the woofer the whole day, and still, the machine was running cool. I called the owner and informed her, and she was very happy. So was the tech.