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Did something on KLH Model 5 —help

B

BernieH

New Member
Hi, thought I was finishing up a successful Model 5 recap, 1st one was great and sounds terrific. On the second one the cover was complete and begat to reassemble...cover back in, sealed, replace putty on midrange, reinstalled mid range all good. Put the tweeter in (I know it worked prior, after I connected it and tighten it down (maybe a little too much) I was working on the woofer and I heard a pop...sure sounded like it came from the tweeter but I though no how can that be I haven’t hooked them completely up yet...thought must have been water/flux some got onto my soldering iron. Finished everything hooked up both speaker second one has no high end. Went to UTube and played 20-20khz tone, first one great, second one cut completely off around 3800Hz.

what happened here, how can anything happen without being hooked up, what is my fix?

I figure if I hooked things up wrong I would have problems once I tried to use them but it was still half apart. I am quite certain something happened right then but am at a loss as to the cause so therefore the solve — appreciate
 
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First thing: remove the tweeter, test it outside the cabinet, maybe with a multimeter, maybe with the speaker wires with your amp set on a low volume, just for a moment.
 
Charged capacitor that let go when the woofer got connected? I know on some bigger caps at high voltage they should be shorted before working on them, but I don't know if that applies on these small values.
 
alteclipsch said:
Charged capacitor that let go when the woofer got connected? I know on some bigger caps at high voltage they should be shorted before working on them, but I don't know if that applies on these small values.
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Yeah, but OP was just done working on the speaker. Presumably it had been sitting for a while. Even if nonpolar caps can hold a charge (can they?), it wouldn't be for that long.
 
swechsler said:
Yeah, but OP was just done working on the speaker. Presumably it had been sitting for a while. Even if nonpolar caps can hold a charge (can they?), it wouldn't be for that long.
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Yeah I suppose that's a stretch, I just can't imagine what else it could be. It's never happened to me in the dozens of speakers I've rebuilt/restored.
 
I was putting a new fan motor capacitor in an a/c condenser and did the requisite short before removing it. It was like a lightning bolt. Big weld scar on my cheap screwdriver. Course it looked like this:
PD_0042_403_A2509-110.jpeg
 
And also it was subjected to 120V-240V before you did that. Amplifiers don't put out anywhere that amount of voltage.
 
swechsler said:
And also it was subjected to 120V-240V before you did that. Amplifiers don't put out anywhere that amount of voltage.
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No, but to play devil's advocate, how much does it take to fry a skinny tweeter voice coil. Not that it did, but what happened here?
 
Okay, I pulled the tweeter testing it by itself, nothing at all no music, no hiss, no crack nada. Rather than removing the woofer and matching the crossover to the schematic (which I did before closing it in the first place, I grabbed an old tweeter I had laying around ( not near a match but none the less a tweeter)) and things worked as they should.

From this I assume blown tweeter but as I mentioned previous I know it worked before even to the point where not having heard a Model 5 before, I debated if it even needed recapped (which it did). So it is more about me understanding what the heck happened. In hindsight I did crank down on the mounting screws a bit much, the corners of aluminum face plate did slightly begin to bend down— could this seemingly extra pressure have caused some sort of problem with the diaphragm or wire connection internal? Something to cause a “pop”? I wasn’t positive the pop came from the tweeter when it happened, I had my back turned just seemed odd that something would happen when nothing was hooked up and the speaker was still half apart. As I think about it it was not an audible pop through the tweeter more like a pop/crack of something snapping.

appreciate thoughts -b
 
As luck would have it there is nothing currently posted on eBay for accurate replacement. I’d like to get a look at this tweet just on the chance that something could be repaired. Looks like the mesh cover is glued onto the aluminum frame/basket. Does this come off with by scoring around the perimeter and gently prying? I have not been able to find anything; however, can anyone point me to a thread / info on what to do, what to look for as a potential fix, or is the a mute point / dead is dead?
B
 
Don't toss it before testing with a meter. It could be a broken tinsel wire just under the mesh, even buried in the bedding stuff they used. I've been working on one and have removed the cone and voice coil intact, I'll post a pic or two when I get home.
 
BernieH said:
As luck would have it there is nothing currently posted on eBay for accurate replacement. I’d like to get a look at this tweet just on the chance that something could be repaired. Looks like the mesh cover is glued onto the aluminum frame/basket. Does this come off with by scoring around the perimeter and gently prying? I have not been able to find anything; however, can anyone point me to a thread / info on what to do, what to look for as a potential fix, or is the a mute point / dead is dead?
B
Click to expand...
Gently heat the screen glue with a heat gun/hair dryer and it should
come off fairly easily.
 
I did get the mesh off, still not sure how it would have happened not to mention “pop” but one of the very very thin wires located near the red is broken, the other seems fine but they are tiny tiny I assume to the VC
 
BernieH said:
I did get the mesh off, still not sure how it would have happened not to mention “pop” but one of the very very thin wires located near the red is broken, the other seems fine but they are tiny tiny I assume to the VC
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That's typically where they break, and many folks have been able to solder that connection (carefully). Need to remove the varnish from both ends and use a warm pencil gun to do that. I've done a couple that way and it's worked both times.
 
Here's mine, disassembled. The red arrow is the break, under the bedding. There is continuity everywhere else. I'll jump the break with a single strand of speaker wire, then I have to center the vc and glue it down with construction adhesive.

This is from a spare I've had in a drawer, so little to lose.
20210305_133553.jpg 20210305_133534.jpg 20210305_133840.jpg
 
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