Vintage HiFi Audio Forum
Repair / Help Forum => Repair / Help => Topic started by: sean283 on July 30, 2014, 09:38:11 AM
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Hi Folks, it's been awhile.
Life is settling down at last and I have time to play with audio again.
So, years ago Tom hooked me up with a pair of Yamaha NS-690II speakers.
Love those things and I've been waiting for another pair to surface.
All the ones I've seen are always 1000 miles away and very expensive.
The other day, I snatched up a rather beat up and inexpensive pair.
Work? Of course, not. When a seller says "sounds great", just assume it doesn't work.
You get what you pay for right? Anyway, one of the mids isn't working.
I put a meter on the voice coil and it is showing continuity and reading about 3 ohms or so. So, the voice coil isn't open.
I metered out the L-pad for the mid and it appears to be working (0 to around 7 ohms).
So, I guess that leaves the crossover.
do you think a crossover cap failed open? Or?
Comments? Suggestions?
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Did you measure the DCR of the overall speaker at the terminals?
What is the impedance of the midrange driver? 4 Ohm, I'm assuming?
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Since you have a pair, and one works and the other doesn't you have the perfect testing dummy to work off of. See what matches between the two and what doesn't match. There may be a lifted trace on the crossover if it uses a board or it may be a cap that has dried out entirely some how.
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Not that it means much, but the last few bad crossovers I came across you could visually see that they were bad (burn marks, etc).
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Good to see you're still alive Sean!