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First of all I’d like to say that I have no experience restoring audio, but I am pretty handy and up for a challenge. With a good explanation I’ll be ready to go. I posted this question in another thread but there was no response, so I thought a new thread might get more attention. Also this is basically my first post and I might not know all the lingo. Anyway, here we go.

I have a Sony MHC-7900 system with Sony SA-H7900 speakers. The system has been collecting dust for the past twenty-something years. I’d like to revive them since it is supposed to be a great system, but the tweeters (Sony 1-504-388-11) in the SA-H7900s are very quiet. I already checked if it was an equalizer problem and it was not. With a flat equalizer there is hardly any sound coming from the tweeters. This problem is also shortly discussed in this thread, but that hasn’t been of much help.

One tweeter was slightly quieter than the other. I took it apart and cleaned it following this youtube video. I first cleaned it with dish soap, which made a small improvement. Then I did it again with cleaning spirit, which made no noticable difference.

As far as I understand either the electrostatic foil is not conductive anymore or the high voltage circuit doesn’t work. The fact that both speakers have the same problem makes me think that the foil is the culprit, not the circuit. For those that are interested, I found a service manual of this loudspeaker.

Does anyone know what to do next? Are there still replacement parts available? I’d love to restore this system in it’s old glory. Thanks in advance!