I have some powered studio monitors (Event 20/20) that have been misbehaving for some time. The electronics in the left part of the circuit have been producing a white noise type distortion at medium to higher volumes, especially in response to bassy sounds. Then one day they started producing intermittent bursts of static regardless of the input. It is definitely the electronics and nothing to do with the speakers themselves or the cables.
Capacitors seem to be the most likely culprit (I could be way off base, though) and so I set about trying to test some of them today. In particular I noticed (discovered this somewhat accidentally) that if I brush certain contacts on the back of one part of the circuit, the sound would be normal for about a second at which point the static would start to gradually come back. This tells me probably a capacitor is charging up and then malfunctioning. This part of the circuit contains several 22microfarad electrolytics. I also tested the two large 10Kmicrofarads and those came back with normal readings. However, when I went to test the 22's, some of them came back normal while some of them read over 9K microfarads. I have never really tested caps before and I thought that if it was a bad cap, it would read much lower than what one would expect. I have tried searching for info about this but can't come up with much. What does it mean if my meter says some astronomically high number when testing the cap? Are these caps also bad or is it the circuit itself that is somehow coming into play here and I would have to remove the capacitor from the board to properly test it? In particular I find it suspicious that the readings for these smaller caps are about the same as the larger caps on the board.
The closest authorized Event repairer is asking $80 minimum to even look at these things so I think if I can figure out which are the bad components I can replace them myself for cheaper. It's certainly within my skillset to replace components but I have no real experience with diagnosing this kind of thing. Thanks in advance for any suggestions!
Capacitors seem to be the most likely culprit (I could be way off base, though) and so I set about trying to test some of them today. In particular I noticed (discovered this somewhat accidentally) that if I brush certain contacts on the back of one part of the circuit, the sound would be normal for about a second at which point the static would start to gradually come back. This tells me probably a capacitor is charging up and then malfunctioning. This part of the circuit contains several 22microfarad electrolytics. I also tested the two large 10Kmicrofarads and those came back with normal readings. However, when I went to test the 22's, some of them came back normal while some of them read over 9K microfarads. I have never really tested caps before and I thought that if it was a bad cap, it would read much lower than what one would expect. I have tried searching for info about this but can't come up with much. What does it mean if my meter says some astronomically high number when testing the cap? Are these caps also bad or is it the circuit itself that is somehow coming into play here and I would have to remove the capacitor from the board to properly test it? In particular I find it suspicious that the readings for these smaller caps are about the same as the larger caps on the board.
The closest authorized Event repairer is asking $80 minimum to even look at these things so I think if I can figure out which are the bad components I can replace them myself for cheaper. It's certainly within my skillset to replace components but I have no real experience with diagnosing this kind of thing. Thanks in advance for any suggestions!
