These little paper cone tweeters are completely sealed units, which is typical, and just as typical, the tinsels are housed inside the rear chamber. As it is typically the tinsels that are broken when a tweeter is blown, we must remove the cone to access the leads. For these Peerless tweeters, the surround for the cone is actually a folded extension. So, a sharp knife or thin blade of some sort must be used to very carefully cut the surround off, attempting to keep it as intact as possible.
- JP
Pulling the cone, it becomes obvious that these tweeters do not have spiders, unlike larger cone drivers. So, once the surround is cut loose, there's nothing more to remove other than the intact tinsel from the connectors. To do this, use a low wattage soldering iron to melt the solder on the connected tinsel and gently pull the cone free. I emphasize gently as the magnet wire used for the tinsels is the same as that in the voice coil and being for a tweeter is mighty fine and fragile.
You can see that in place of a spider, there's just a little bit of polyfill. This helps absorb the backwave from the cone, but also adds mass to some degree, so it might be serving multiple roles. Being a tweeter, the excursion required of the cone is nearly imperceptible, so the stiff folded paper surround and the polyfill is sufficient to hold the voice coil in alignment.
- JP
With the cone free, a quick glance will reveal the condition of the tinsels. Being such fine wire strung straight from the voice coil to the connectors, it is particularly fragile and the primary point of failure in these Peerless cones. A clipping amplifier or even poking the cone too hard at an off angle can burn/break one or both of the tinsels quite easily. Even soldering wires to the connectors and using too much heat can let a tinsel escape from the connector thus making for a "bad" driver.
In the attached picture, you can barely see the red enameled wire. The tinsel on the right is intact and still has some solder on the end. That on the left is broken at the midpoint, perhaps from one of the above possibilities or it may even have been jarred too hard after a few decades of life had piled on it.
- JP
Use the discussion in the early part of this thread to add a piece of wire to the stub of the tinsel. Check continuity of your fix and trim it to the same length as the original tinsel. If both were gone, trim the length to come to the edge of the surround to ensure good contact with the backside of the connectors.
- JP
Holding the cone and repaired tinsels at a slight angle above the basket, position the unit such that the edge of the tinsels touch the backside of their associated connectors in such a way that they'll be parallel when the cone is returned to its original position. While the tinsels are touching the back of the connectors, use your low wattage iron to solder the leads in place. Be careful here as the wires are fragile and too much flexing can break them off at the voice coil and not only undo your work, but require much more to fix. You'll also want to keep a steady hand here.
When the tinsels are soldered, carefully place the voice coil back in the gap and set the cone down. Using the aforementioned battery trick, center the cone and gently check for rub and the tinsels for any binding or the like. Remember, being a tweeter means little excursion, so you don't need to press it far in. When you think it feels fine, add a bead of surround glue between the edge of the paper surround you cut free earlier and the basket flange. Regular Elmer's white glue should work fine. Leave the battery connected to make sure the cone remains centered as the surround placement is important due to the lack of spider. (Don't do near as large and messy a bead as shown in the picture -- I got in too big of a hurry and made for an ugly, albeit working fix.)
When the glue dries, check again for proper continuity and rub. If everything checks out, reinstall the driver, being careful not to overheat the connectors, and enjoy the music.
- JP