Hi I am having trouble with a Harmon Kardon powered Sub. Out of no where, the sub started making random popping/thunder sounds even when off. This sub has not been used very much and has never been abused.
I took the amp out and noticed that with it on, if I moved the little board (sorry, don't know what its called) that is soldered to the input board the noise would get worse or improve. This made me think it was a bad solder joint. I de-soldered the little board and scraped the glue that was put on it off. I cleaned the board with a brass toothbrush and re-soldered the header pins as well as the pins where the wire connector are. I also re-soldered the 2 caps on the little board as well as the 2 caps that are right next to the board on the input board.
I re-soldered the little board back onto the input board and tested it. Now, the sub works without the random popping/thunder sounds, but now it will not go into sleep mode (auto). If I unplug the input cable and select auto mode instead of on mode and plug the sub into the wall outlet, when the amp goes into sleep mode (red light instead of green) you get a constant rumbling sound even with the input wire disconnected. If I change it to on mode the rumbling goes away and the sub seems to work.
I am assuming it has something to do with the little board on the input board but am not sure where to begin. Please help.
I took the amp out and noticed that with it on, if I moved the little board (sorry, don't know what its called) that is soldered to the input board the noise would get worse or improve. This made me think it was a bad solder joint. I de-soldered the little board and scraped the glue that was put on it off. I cleaned the board with a brass toothbrush and re-soldered the header pins as well as the pins where the wire connector are. I also re-soldered the 2 caps on the little board as well as the 2 caps that are right next to the board on the input board.
I re-soldered the little board back onto the input board and tested it. Now, the sub works without the random popping/thunder sounds, but now it will not go into sleep mode (auto). If I unplug the input cable and select auto mode instead of on mode and plug the sub into the wall outlet, when the amp goes into sleep mode (red light instead of green) you get a constant rumbling sound even with the input wire disconnected. If I change it to on mode the rumbling goes away and the sub seems to work.
I am assuming it has something to do with the little board on the input board but am not sure where to begin. Please help.
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