I got my hands on a Klipsch SW12- it had a loud power supply hum and intermittent signal. I figured it was a bad ground connection or some caps went bad, so I traced the wiring and checked for continuity. Ground came up good, so I moved on to the 30 year-old electrolytic capacitors. I put my Mouser order in and waited a week for parts to show up.
Parts came in today around 1, and I spent the next four hours checking and marking polarity, desoldering old caps, and installing 22 new capacitors.
I plugged the unit in to the wall and hit the on switch. No smoke, which was nice, and no hum, which was nicer. Before, it would hum with nothing connected. Test 1 complete.
I unplugged it from the test outlet and hauled it upstairs to the home theater. After fishing out some RCAs, I plugged everything in and turned the system on. Got faint signal through the sub with the knobs all the way up, and a new, lower hum, but only when the sub was connected to the AVR's sub-out. No hum otherwise.
I'm not sure where to go from here... something is rotten between the input jacks and the amplification stage, but I'm not sure what it could be. The hum is volume dependent, so amplification seems to be working but signal isn't reaching. I'm back to thinking it's a grounding issue because the hum is only there when the input is connected.
What are my next steps for troubleshooting? Am I missing anything obvious?
Parts came in today around 1, and I spent the next four hours checking and marking polarity, desoldering old caps, and installing 22 new capacitors.
I plugged the unit in to the wall and hit the on switch. No smoke, which was nice, and no hum, which was nicer. Before, it would hum with nothing connected. Test 1 complete.
I unplugged it from the test outlet and hauled it upstairs to the home theater. After fishing out some RCAs, I plugged everything in and turned the system on. Got faint signal through the sub with the knobs all the way up, and a new, lower hum, but only when the sub was connected to the AVR's sub-out. No hum otherwise.
I'm not sure where to go from here... something is rotten between the input jacks and the amplification stage, but I'm not sure what it could be. The hum is volume dependent, so amplification seems to be working but signal isn't reaching. I'm back to thinking it's a grounding issue because the hum is only there when the input is connected.
What are my next steps for troubleshooting? Am I missing anything obvious?