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