HPM-60: Can you repair a dead mid range?

euphemismos

New Member
I recently replaced a dead mid-range driver in one of my HPM-60's, and I'm wondering if the dead driver is worth repairing (assuming it can even be repaired), or if I just need to trash it. Any thoughts or opinions would be most welcome. I posted in the Pioneer forum, but so far have not received any responses. To the eye, it looks perfect so the thought of throwing it out just doesn't seem right.
 
The mid was just dead. No sound coming out at all. The reason I know it's the speaker is just because the replacement I put in is working fine. Full disclaimer: I'm a long time audio fanatic, but I'm VERY green when it comes to the DIY ethos of owning vintage gear. However, I'm eager to learn. I guess I need to buy a volt meter :).
 
If you're keen to learn a decent DMM will be an asset.
The failure could be a burnt-out voice coil which is probably not repairable/expensive or a broken connection somewhere between the terminals and voice coil which often can be repaired. The ease of repair depends largely on how easy it is to find and access the break.
 
You can get a cheap multimeter at Harbor Freight, or a better one - there are excellent ones around $50 and they are useful around the house for a variety of things.
 
what is the trouble? is the voice coil open? you can tell us more by checking it with a multimeter...
Forgive my incompetence fellas, but I'm brand new to the DIY/vintage audio game. I was able to get my hands on a multimeter, but I'm not sure what to do to test the speaker. I assume you just put the meter on the 2 speaker terminals? What kind of reading am I looking for? I've heard that if the voice coil is shot, then it's pretty much game over. I'm not sure if this is the problem or not. Nevertheless, it seems crazy to just toss it out.
 
Set your meter on Ohms and check across the terminals. No sound from a driver will probably manifest as infinite or very high resistance. A working 8 ohm driver will usually be in the 5-6 ohm range.

Also, carefully examine the solder joints on the driver's terminals, and the wires (tinsel leads) that go from those into the cone/voice coil. Look for breaks or bad looking solder joints. Once in awhile there is a problem here that you can fix rather easily.

If it's not something like that, then the voice coil is burned open and the driver is not readily fixable. In that case, theoretically it could be reconed but it's not that easy to find a proper cone/voice coil for any given vintage driver, so unless it's a rare valuable one, they usually get tossed.
 
Good info from tox but just one other point; ensure the driver is disconnected from the circuit, otherwise you may get incorrect readings.
 
If its open circuit you may be able to repair the small leads to the voice coil if the break is visible. I've repaired some coincident KEF tweeters this way. However like the others say - a meter is essential to test for this
 
Thanks to everyone for the info. I was finally able to test the speaker last night. When I put the meter on the terminals, I get nothing. No reading whatsoever. Just to be sure it wasn't the meter, I tested my other working mid range and sure enough, it's right at 6 ohms. The space between the cone and the cage of the speaker is very tight and small so it's really hard to get a good look in there. Nevertheless, from what I can see the tinsel leads appear to be unbroken. I can't really see the solder joints at all. I'm guessing the non-reading must mean that the voice coil is bad.
 
Tap on the cone, and especially the joints where the tinsel passes through the cone and is soldered to the voice coil wire, while putting a low level signal through the driver. If you get any sound, its probably the solder joint were the tinsel and VC wires are soldered -- they do go bad and need to be reflowed. Alternately play fairly high volume through it, and if it responds at all, that's a classic sign of that problem.
 
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