Disappointment permeates all things Wah+Fuzz here at RetroTone®. Our repair job on the inductor did not work so we are forced to seek another solution. Good thing we checked out all the options for inductors in Wah-Wah pedals. This article reviews where we are in the repair/rebuild process, the schematic of the color sound Wah+Fuzz and what is the most appropriate solution for Greg's Wah+Fuzz.
I tried to solder a lead onto the tiny stub. The weight of the lead snapped the stub off at the body of the inductor. Usually in the situation where the inductor lead breaks off, we just open the inductor and take off a wind or two to give some slack. If you remember, the inductor was glued together and therefore could not be opened.
We will have to replace the inductor. Bummer. Hope there wasn't much mojo on there.
The photos below show the "Halo" on the left and the "Stack of Dimes" on the right.
"Halo" is a manufacturer name. "Stack of Dimes" is American slang because the inductor package is about the same size as a stack of 10 cent coins. There is one thing these inductors all have in common. They are all "Pot Core Ferrite Inductors". No mojo, no magic. These inductor's form factor, material composition and magnetic properties have been standardized since the late 1950s through several international standards organizations. The standard for Pot Cores is form the International Electrotechnical Commission, document IEC 62317-2:2010. This document started as IEC133 and IEC 133 replaced an earlier document. There is an excellent book on all things electromagnetic entitled "Goldman, Alex. Handbook of Modern Ferromagnetic Materials Norwell: Kluwer, 1999."
Why does all this matter? Because we are going to have to wind our own inductor. There are a couple of things to remember about our inductor. First, 500mH is a very large value. Finding this value off the shelf in the day and age of high tech, high frequency, surface mount devices is nearly impossible. I already discovered Castledine Electronics won't sell direct. The Whipple "Halo" won't fit on our board although the Whipple is a hand wound pot core with very nice mounting hardware.
We can probably get close on the form factor and ferrite material with a little more research since the form factor and materials have been standardized before the wah was invented in the 1960s.
The photo below shows our original inductor with valuable information printed on the top. I can see the manufacturer logo. It looks like a capital H with a lower case s centered. The designator N22, a Z above 49 and the number 70. I do not recognize the logo. This inductor is most likely English and/or at least European. The N22 and the Z49 don't look familiar as far as inductors go. These could be part number or a lot number or a week of manufacture. The 70 could denote a year or a ferrite material type.
The markings don't give us much to go on but we do know it is a pot core common to the early 70s and is used in low current, low frequency, filter applications. I was able to measure the thickness of a tiny bit of the wire. The wire used in our inductor was 40AWG (very fine) wire. Most likely because we needed so many turns for the 500mH value and it is a low current application. We also know that almost all of the wah-wah pedals use the same schematic so our inductor should work in almost any wah-wah.
UPDATE Our reader, Gonzalo, pointed out that the logo on the inductor is from Seimens. Thanks Gonzalo. I did a bit of research and found this logo sheet showing the evolution. The number "N22" is the material type. Consequently our replacement inductor works as a near replacement.
Next time, we do the deep dive into what it takes to make our own inductor to replace the one in Greg's ColorSound Wah+Fuzz. I'll do more searching on the internet to see if anything stamped on our inductor shows up to give us some clues...