EV PL88L & N/D267 Dissection

I have a couple of EV microphones with no output, a PL88L and N/D267, begging to be fixed. Today I opened them up to see what’s inside.

 

Infinity Qb EMIT Tweeter Repair

Lots and lots of shows at the Gillioz these days, but I’m still finding time to take on a few personal projects here and there.  When I saw a set of Infinity Qb speakers on Craigslist for $50 I couldn’t pass them up.  As seen in an earlier post, I restored a set of Infinity RS5b speakers and fell in love with their sound.  The Qbs are essentially the grandparents of the RS5b.

However when I arrived to buy the speakers, a quick visual inspection (and subsequent listening) revealed both EMIT planar tweeters where non-functional.  You could easily see a tear in each of the drivers, so I talked the guy in to letting me take them home for half his asking price, which seemed fair for both of us as the woofers and mids were working just fine.  If nothing else I could always part the speakers out, though I really hate promoting that practice.

I did a little research online and read about a guy who fixed some EMIT tweeters with this conductive paint used for repair automobile rear-window defrosters.  My local auto parts supplier had some for about $10 a bottle.  An additional trip to Hobby Lobby to find the smallest paint brush I could (the one included with the paint was too wide) and I had everything I needed to tackle the project.

The whole task was a little daunting, as the line I had to paint to restore the circuit was so very small, but it’s hard to break a tweeter that’s already broken so I just dove right in.  I filled in the missing gaps and let the tweeters sit overnight before running audio through them (though I did confirm I had completed the circuit with a volt/ohm meter).

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Low and behold, it actually worked.  I’m still in disbelief, but both tweeters work and sound just as they should.  One of the two tweeters quit working after a few seconds, but a second coat of conductive paint resolved the issue.  We’ll see how they hold up after additional hours of play time, but I’m really happy about how things turned out.

Now I’ve got a (second) cool set of vintage Infinity speakers and am only out about $37.50.  Let the listening commence!