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Post by svart on Feb 2, 2022 12:08:51 GMT -6
Years ago I had some junk paging mics with broken coil leads, and managed to fix all of them. Don't know why I went there, but it was possible! If I could only figure out how to get some solder on this teeny wire without burning it off, I can fix this capsule and perhaps one other. As it is, I'm at the lowest setting on my iron. |
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Post by svart on Feb 3, 2022 9:15:19 GMT -6
So I experimented once again trying to get these stupid little wires soldered. I got my iron down to 400F but it was barely enough to melt the lead solder. I had to go up to 500F to try the lead-free solder. The lead free solder was flux cored and that seemed to tin the wire much better, but the wire still burned back some. I switched to lead solder and I was able to get the wire to bond with the strand, finally!
Unfortunately during the process I dropped hot rosin on the diaphragm and it melted a hole through it.
It was a good experiment though. I have one more capsule with no continuity that I can try this on.
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Post by svart on Feb 4, 2022 8:13:25 GMT -6
Sad news for those who are following this thread. The last dead capsule was truly dead. I found that the wire from the capsule to the post was broken, something I think I might have done when getting the humbucking coil basket off the diaphragm, and I spent a good part of an hour gently cleaning the glue and such off the post and wire. I was able to tin the wire and get it soldered to the post..
Only to find that it still didn't have continuity.
After messing with it and double checking both sides, I decided to take the diaphragm off the base only to find that the wire was broken at the coil itself as well. There's no fixing that.
I *might* try taking the coil off the melted diaphragm and swapping it to this diaphragm at some point although I currently don't know how to do it. I guess I have nothing to lose trying.
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Post by svart on Feb 7, 2022 9:32:08 GMT -6
So I tried something crazy. I swapped the coils from one diaphragm to the other. I was able to easily remove the coils and unwind a half turn of both leads to get enough wire to solder. I took the good diaphragm and was able to tack the other coil to it, but I had a really hard time getting it lined up on the crease where the other coil was removed. I think part of the problem was the remaining glue and part of the problem was that the coil distorted slightly when being removed. Even working as gently as possible I could only barely get it lined up. I was also not able to get it perfectly aligned in the magnetic gap but I can't seem to notice any rubbing. The gap is fairly wide, maybe about 2x the thickness of the coil, which helped.
I'll give it a try tonight.
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Post by johneppstein on Feb 7, 2022 15:10:18 GMT -6
I've used qtips like you, and also fuzzy wire craft project thingies (what are those called?), which work better I think. Pipe cleaners. They're called pipe cleaners.i |
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Post by svart on Feb 7, 2022 17:46:26 GMT -6
Well, the swapped coil capsule works. It doesn't sound a good as the others but it works at least. It's surprisingly close though. I might try reseating the diaphragm at some point but right now it's not a priority.
So now I have 8 perfectly working mics.
Time to clean them up and sell them.
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Post by stratboy on Feb 10, 2022 19:59:12 GMT -6
You are the 421 whisperer, Chris!
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Post by Deleted on Feb 14, 2022 4:49:07 GMT -6
I've used qtips like you, and also fuzzy wire craft project thingies (what are those called?), which work better I think. Pipe cleaners. They're called pipe cleaners.i I prefer fuzzy wire craft project thingies.. Doesn't roll off the tongue but sounds interesting. |
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Post by johneppstein on Feb 15, 2022 12:29:07 GMT -6
Pipe cleaners. They're called pipe cleaners.i I prefer fuzzy wire craft project thingies.. Doesn't roll off the tongue but sounds interesting. For sure. Might be a bit of a problem when asking directions from a distracted clerk though.... |
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Post by damoongo on Nov 3, 2024 19:55:15 GMT -6
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Post by damoongo on Nov 3, 2024 20:29:35 GMT -6
Well, the swapped coil capsule works. It doesn't sound a good as the others but it works at least. It's surprisingly close though. I might try reseating the diaphragm at some point but right now it's not a priority. So now I have 8 perfectly working mics. Time to clean them up and sell them. Did isopropyl end up causing any problems for the diaphragms? |
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Post by svart on Nov 4, 2024 6:22:28 GMT -6
They all looked like that. If you're referring to the green center vs. the white center in my pics, that's just the plastic behind the diaphragm. I've seen green, white and grey in various capsules. |
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Post by svart on Nov 4, 2024 6:23:01 GMT -6
Well, the swapped coil capsule works. It doesn't sound a good as the others but it works at least. It's surprisingly close though. I might try reseating the diaphragm at some point but right now it's not a priority. So now I have 8 perfectly working mics. Time to clean them up and sell them. Did isopropyl end up causing any problems for the diaphragms? No. Isopropyl is fine. Do not use acetone! |
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Post by damoongo on Nov 4, 2024 7:35:58 GMT -6
Did isopropyl end up causing any problems for the diaphragms? No. Isopropyl is fine. Do not use acetone! Thanks! This one has full low end, but distorts at high spl. Did you ever experience any like that? Cleaned the diaphragm gently and reassembled but the distortion remains… |
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Post by svart on Nov 4, 2024 8:41:18 GMT -6
No. Isopropyl is fine. Do not use acetone! Thanks! This one has full low end, but distorts at high spl. Did you ever experience any like that? Cleaned the diaphragm gently and reassembled but the distortion remains… Could be a few things. The diaphragm might be offset slightly and when it gets close to full incursion, the coil could be touching something. I found that the diaphragms on the older ones come loose a little as well. The glue that holds them down seems to dry up. You might gently see if any of the outer edge is loose. |
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Post by damoongo on Nov 4, 2024 10:59:47 GMT -6
Thanks! This one has full low end, but distorts at high spl. Did you ever experience any like that? Cleaned the diaphragm gently and reassembled but the distortion remains… Could be a few things. The diaphragm might be offset slightly and when it gets close to full incursion, the coil could be touching something. I found that the diaphragms on the older ones come loose a little as well. The glue that holds them down seems to dry up. You might gently see if any of the outer edge is loose. Thanks again, Svart. Did you remove any diaphragms? I feel like the potential for destroying the voice coil wire is very high. Felt lucky to not have ruined it when detaching one end of the humbucking coil wire from one of the terminals to get the humbucking assembly off to expose the diaphragm. Any tips you’ve got if you’ve removed or recentered a diaphragm? |
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Post by bikescene on Nov 4, 2024 12:03:40 GMT -6
I think the MD421 I bought from svart was one of these repaired versions. I’ve been enjoying mine on guitar cabs, often between the cap edge and cone edge off axis. Also worked well on kick drum for a change of pace from the typical Beta 52 that I use.
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Post by svart on Nov 4, 2024 14:55:40 GMT -6
Could be a few things. The diaphragm might be offset slightly and when it gets close to full incursion, the coil could be touching something. I found that the diaphragms on the older ones come loose a little as well. The glue that holds them down seems to dry up. You might gently see if any of the outer edge is loose. Thanks again, Svart. Did you remove any diaphragms? I feel like the potential for destroying the voice coil wire is very high. Felt lucky to not have ruined it when detaching one end of the humbucking coil wire from one of the terminals to get the humbucking assembly off to expose the diaphragm. Any tips you’ve got if you’ve removed or recentered a diaphragm? I tried it with a dead diaphragm. I took it off and pulled one of the wires off of the coil and tried to reattach it, but that wire is soooo thin that it would just burn even at the lowest soldering iron setting. I think I got one to work but the heat warped the diaphragm. I think the moral of the story is that they shouldn't be taken off if they're working at all. They most likely had a precision jig to build them back then. |
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Post by frans on Nov 14, 2024 4:24:42 GMT -6
I got a spool of leaded thin solder for jobs like these, which i very rarely do anymore. The leaded solder has a lower melting temperature.
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Post by johneppstein on Nov 20, 2024 12:49:41 GMT -6
I got a spool of leaded thin solder for jobs like these, which i very rarely do anymore. The leaded solder has a lower melting temperature. Specifically, 63/37 Eutectic melting point lead based solder. Eutectic melting point means it has the lowest possibl melting point, with little or no slush phase.
Not all leaded solder is equal. Normal lead solder is 60/40, not 63/37.
Don't use lead-free solder for electronics work.
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