Unidyne SM57 Update: SUCCESS!

No more hole digging! Time to fill 'er back up!

Great news, after last night I had a chance to look at the "broken" SM57s that had just arrived and discovered, on the surface, that the issue simply had to do with soldering of the wires on the inside to the lugs on the capsule. It ended up being literally that simple for one of the microphones. The "rattling" reported in the listing was just the nuts and washers for the retention of the capsule rattling in the handle. They just needed to be put back on, and all was good as new. That one will be a quick sale!

(stock photo from the 'net, so you can see what the solder job looks like)

The second one was not as simple. I noticed the PCB with the lugs for the capsule was spinning freely, which meant two things: first, that the nut holding the PCB down was loose, and second, that the thin wires coming from the coil of the capsule had broken.

I ended up trying to re-solder the coil wires back to the lugs, but there was barely enough length, and the minute the PCB spun even a little, the wires broke. So I tightened the nut holding the PCB down TIGHT, and then grabbed my hook-up wire. Stripped the vinyl off the outside of it, pulled out a couple copper threads, soldered one to each of the two lugs, then VERY CAREFULLY soldered the thread to the coil wires.

Disclaimer: This is not the easiest thing in the world, as the coil wires are enamel coated and won't take solder until the enamel is removed. You can either get some high-grit (like 240 or above, to avoid sanding through the wire) sandpaper and carefully sand the enamel off, or if you have good temperature control of your soldering iron, you can put it at a temperature that won't damage the wire but will melt back the enamel. I chose the latter, and got the solder to hold. Wired it back up, and...voila! Worked!

Knowing that the capsule fully worked, I went about putting the Unidyne cap on the Shure capsule and soldered the capsule to the Unidyne base (containing the much-touted Unidyne transformer). It works like a charm!

Given the work I've put into the Unidyne, I'm definitely going to keep it, and probably going to paint the body white, just to look cool. In all, this took very little investment, and when I sell the fully-working Shure SM57 that took hardly any work, you can admit that I have quite the deal:

- Bought the Unidyne III for $50, found out it was irreparable
- Bought the 2 Shure SM57s for $50, got them both working
- Moved one Shure capsule into the Unidyne body and cap
- Can sell the other working SM57 for around $70, with a negative net of $30

But wait! There's more!

I have a fully working body from a Shure SM57 and a completely un-working Unidyne SM57 capsule. I might put both up for sale and see if there's anyone interested. Probably sell both for $20-30 which would mean fully recuperating my investment, and still having a Unidyne SM57.

It's been a long ordeal, but I think I see light at the end of the tunnel! Here are the lessons I learned from this complicated flip (although it's not over yet!):

1. Don't get ahead of yourself on thinking you'll make money, especially if you have no idea the extent to which the repairs will be.
2. Don't give up on a botched repair; look for opportunities that will let you get out of whatever mess you're in.
3. When possible, consider alternatives that may cost more, but will result in you keeping or being able to sell a piece of high-quality gear.

~C

Maybe Digging the Hole Deeper? More on Unidyne SM57

My sentiments exactly. Update on the Unidyne SM57.

After the horrible failure of a fix earlier (and I know the reason is because I over-confidently said "profit, here I come!), I set the microphone aside, but it called to me.

"FIX ME"

I knew I was going to wait until an opportunity presented itself, but just then, an opportunity presented itself.

2 SM57 microphones, for $50. Both were sold untested, as-is, from a seller who got it from a storage garage auction. Am I really just digging myself into a hole? Maybe not. Hear me out.

According to this forum post and Shure's website on services, even microphones out of warranty are covered. For $55, they will attempt to repair nonworking microphones, or replace them outright. So, if the bad happens and neither microphone works, I've got the option to get both fixed for $110, and so for $160, I have 2 new microphones, priced at $200 new. Not really anything to profit off of, but I can recoup my money fairly easily.

If either (or both!) microphones work, I'm in luck! I can pull the capsule half of the microphone and solder it into the bottom half of the Unidyne, even going so far as to replace the windscreen and collar with the original Unidyne ones. Now, I fully realize that the microphone is not then a Unidyne, but the capsule has not undergone any significant changes, so it will be literally the same microphone. Maybe worth selling at $150 or so, for a minor profit, or keeping. If both work, I can sell the other working one for $70ish and recoup almost all of my costs, making my Unidyne virtually free. Virtually...meaning I'm willing to net having paid $30 for one of the best microphones around. I might even paint it, just to be coy.

I honestly think the worst case scenario at this point is if they are both fake. That's not terrible, as I'll just send the microphones back for being horribly incorrectly described.

At any rate, it's a lesson to myself not to speak too soon, and a chance to hopefully vindicate myself after speaking too soon. I'll keep you updated!

~C

Unidyne SM57 Update...or How I Spoke Too Soon

I must confess, I've made a mistake. I've jumped to conclusions, and it came back and bit me.

The recent SM57 acquisition is a much tougher nut to crack.

I did all of the soldering I had mentioned before, using shrink tubing to ensure a good connection and no shorting. After doing all of that work, nothing. No signal.

I eventually got to the point where I had to remove the R57 capsule from its housing and discovered the real culprit: a coil wire had broken.

Anyone who has worked on SM57s know it's a death sentence for these microphones if the coil wire breaks, especially right near the diaphragm. The only way to restore the microphone would be to remove the diaphragm, unwind the coil a couple turns, re-secure the coil wire, and find some way to precisely return the diaphragm. Near-impossible, and if you pull it off, you have a slightly underwound coil. Probably not enough to make any difference, but this is the sort of work that needs to be disclosed to any would-be buyers and would undoubtedly sell for less. There's just no longer any profit in it.

So what I've done for now is tabled the SM57. My plan is to eventually buy a replacement R57 capsule and wire it into the body, whose transformer should likely influence the sound and make the closest thing to vintage as possible, and keep it. Better yet, buy a used SM57, just in case there is a transformer issue too. Unfortunatly, I have no way to know for sure since the capsule is beyond repair.

Ugh, this is the first time I've had something that's been deemed "un-fixable" -- heck, even Shure's service work with that type of issue consists of sending you a replacement microphone. I could actually do that, but it'd cost $55 and I'd lose the Unidyne and gain a MIM Shure SM57. Just not what I'm up for.

Besides, I already have a sweet instrument microphone. I'll probably put this microphone aside and wait until the right opportunity presents itself. I was hoping for a tech article, but alas. Such is the way things work.

~C

Another Unidyne SM57...the "Fixer-Upper"...

So, from my last flip, wherein I tripled my money in 24 hours by buying and selling an old Unidyne III SM57, I went on the hunt for instrument microphones.

(For myself, I got a slightly less-expensive but responsive instrument microphone from Audio-Technica, the Midnight Blue MB2k. This is going to be my "keeper" microphone, so other purchases are really just for profit.)

Anyways, on ebay, I found an auction for a non-working Unidyne SM57: eBay link and quickly followed the auction, planning to bid the minimum ($60) at the end of the auction.

In a crazy twist of fate, my mobile eBay app wasn't working properly and I missed the end of the auction, where I was going to swoop in. Luckily, I was able to message the seller and ask if he'd be interested in selling the item at a reduced cost, as he hadn't described the issue.

Side note: If you look at the description, you see it "has been worked on" but was non-working, which worried me, as I figured he took it to a tech who couldn't make it work. This turned out to not be the case, as he said he just opened it up and couldn't figure out what was wrong with it.

Lo and behold, I made an offer for $50 and got the microphone. It arrived in the mail yesterday. I finally got to open it up today. Brace yourself...

 So here's the bottom of it. Literally every wire was detached between the body and the capsule. Every. Wire. How is that even remotely "worked on"? No wonder it doesn't work!

This picture is actually quite alarming, as the black wire (read: the ground) is attached to the (+) of the element, rather than the middle, using the eyelet on the table to the right of the image. Sigh. Also, look at the terribly poor soldering job. The frayed wire edges on the right eyelet there are worrisome, as they could easily be in contact with the body, effectively grounding what should remain an isolated loop.

So I basically just need to attach the black wire back to the middle where it belongs and attach it back to the copper bar down inside the body, then connect the yellow wire (which is too short to reach the capsule, just by a little) and the green wire to their respective poles on the capsule, and I guarantee this will work again.

Profit, here I come! :)