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This is a small powered near field monitor which was burning up tweeters every so often.....I connected a dummy load to the tweeter connections and fired it up....A dc voltage appeared and very slowly rose from a few tenths of a volt to enough of a voltage to make the dummy load resistor too hot to touch....I disconnected the pins of the IC chip, a LM3886TF and the problem went away.....so I thought that was the problem...
Installed a LM3886T and I had to install an insulator between the IC and the Heat Sink as the other IC was already insulated...The same problem returned....started to probe around with a "Chop Stick" and discovered that R 96 was actually not making a connection on one lead...re-soldered it and the problem went away....I guess it is possible that the original IC could be good but I didn't want to take the chance of swapping it back in again only to find out it was bad......here is the schematic........
Cheers,
Bernie
Installed a LM3886T and I had to install an insulator between the IC and the Heat Sink as the other IC was already insulated...The same problem returned....started to probe around with a "Chop Stick" and discovered that R 96 was actually not making a connection on one lead...re-soldered it and the problem went away....I guess it is possible that the original IC could be good but I didn't want to take the chance of swapping it back in again only to find out it was bad......here is the schematic........
Cheers,
Bernie
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