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Carmine

KLH Model 5 crossover switch problem

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Greetings everyone.  I re-capped a pair of KLH Model Five crossovers but on one of them the 7,000Hz attenuator switch cuts out in the High position and I get no sound.  The Lo and middle settings are functional and everything else works just fine.

I've checked the schematics and everything seems to be wired correctly.  How can I troubleshoot this?  Do the switches go bad?  I tried cleaning it with contact cleaner to no avail.

Also, for what it's worth, this switch looks different than the other three, like it is a replacement.  It has an opaque plastic cover and the others are clear.  I was unable to upload an image.  Perhaps, it has failed before?  One of the tweeters was not working when I got the speakers which I narrowed down to the crossover network but am not sure if it was this particular crossover, as I lost track.

Any ideas or suggestions?

Thanks,

Carmine

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Welcome Carmine

Try resizing the pics to about 100MB.

I've worked on several Five xo's but never replaced a switch. They may be unobtainium 😐

-Kent

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I was afraid that might be the case.  I put so much time into them I would hate for them to not be totally functional.  Here is the pic.  Switch in question is on the left.

bad switch2.jpg

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hmmmm....

Actually, the opaque one looks like the ones I've worked on. Take a look through Model Five posts here on CSP. Here's one: 

But I'm stumped. If that switch WAS replaced, it's possible it's wired wrong--all those little jumpers on all those solder tabs. There could be some internal break I suppose. If it's just the "High" on one speaker you may have to just live with it.

-Kent

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Thanks, I searched through the forums and the web and came up empty.  Externally everything looks correct according to the schematics I found.  It must be an internal fault to the switch and probably more than I want to take on at this point for fear of making it worse.  They sound good regardless but was hoping for fully functional in case I ever want to sell them.

Best,

Carmine

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Hi Carmine - - welcome to the forum - - I've just got a couple thoughts to add to this discussion. I am slowly working on a pair of Fives and a pair of Twelves, so I've been looking at a total of twelve of these switches. All of mine have the opaque cover, so that is not your issue - - in fact, I've never seen a clear cover until you posted your pic above.

Not sure if you can see very well in these pics, but over time the metal parts in these switches develop a residue of metallic corrosion, and it is necessary to spray and clean these areas with an appropriate electronic contact cleaner. The other point I want to make involves these little double-teeth prongs that clamp together the upper and lower portions of the switch. Unless these are firmly secured, it is possible for the moving parts of the switch to fail to make contact, and this could certainly result in your High position cutting out.

In the one instance where I encountered this problem, the switch did not make a crisp and distinct click-click-click sound; instead it moved with more of a dull touch and a thud-thud-thud sound. Once the upper and lower parts were "snapped" back together, the switch worked every bit as good as the others.

P1120637.jpg

P1120638.jpg

P1120646.jpg

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Thank you for the warm welcome.

Is there a way to take the cover off without breaking in order to clean it better?  I did spray cleaner through the holes as best I could.  However, your insight has me thinking as they all make a dull thud sound as opposed to a sharp click when turned.  Do I just push down on the cover to reseat it or gently squeeze with a pliers?

Impatience got the best of me and unfortunately I resigned myself to live with it and sealed the speaker back up already.  My plan was to keep a lookout for a crossover or parts for sale and eventually swap it out.  Now I'm debating whether to open it up and give your suggestion a try.

Best,

Carmine

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6 hours ago, Carmine said:

Is there a way to take the cover off without breaking in order to clean it better? 

The exposed top hub on the switch has parallel flattened sides, so it appears that a wrench will fit to allow disassembly, but I've never explored this far - - I'd be afraid I couldn't get it back together properly. After looking at these switches more closely, I'm convinced that the spray cleaner should be applied from the outer edge toward the center, just under the circular white (plastic?) ring with the wire terminals.

6 hours ago, Carmine said:

...they all make a dull thud sound as opposed to a sharp click...

Don't overthink this - - - I was merely trying to suggest that there was a noticeably different feel and sound between a properly functioning switch and one that was not properly closed and therefore not making contact.

6 hours ago, Carmine said:

Do I just push down on the cover to reseat it or gently squeeze with a pliers?

With so many wires everywhere, this was a bit of a delicate operation - - - plus, I was unfamiliar with these switches. I think I first tried to re-seat it with a little thumb pressure, but when that did not work for me, I grabbed some needlenose pliers and sheepishly gave it a soft squeeze until it re-seated.....but there is not much to grab onto.

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Yeah, might be worth another look, but as you already know, it takes a bit of effort simply to remove the crossover panel.  Again, I've only had a single experience with this issue, and in that case, upon close inspection the problem switch was visibly different from the others. Fortunately, I was able to spot the minor separation of parts, and was successful in getting them back into proper position so that the switch functioned correctly.

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