This is a bit of a public service announcement, with the aim to help someone else down the line who runs into a similar problem and a similar dearth of helpful information online.

Recently, I found myself with a dead Kawai WK40 keyboard in the Mechlab. After some poking and probing, I found a resistor whose multimeter readings were curious and didn’t seem right. There were a few odd things about the resistor: the body color was unusual, it was positioned on the board in a weird way (sitting a few centimeters above the board, instead of flat against it) and it had a textured finish (it’s not smooth). Most of this I attributed to it being an older keyboard and component-design drift over time. In any regard, I felt I should replace it and see if that reanimated my keyboard corpse.

Because the multimeter readings were inconsistent, I needed to figure out the value of the resistor. Memorizing resistor value color codes sounds about as engaging as cataloging toe nail clippings, so I needed to rely on internet resources to determine the replacement value. This is where the mystery deepened. It was at this point that I realized that the third band in a 5-band code can’t be gold. And that the fifth band can’t be white. Yet, I had a resistor with unambiguous gold and white bands where they shouldn’t be. White is a digit or a multiplier, but not a tolerance. Gold is a multiplier or a tolerance, but not a digit. No combination of yellow, violet, gold, gold, white (or, read the other way, white, gold, gold, violet, yellow) made sense. No matter how you read it, a 5-band code should not have gold as the third band, or white as the fifth.

I checked for older standards, but still came up confused. I checked to see if there were different color code standards in Japan (where Kawai is headquartered), but found nothing. I lurked electrical engineering forums, and while there were threads devoted to this topic, none of the answers made sense (because, ultimately, they were wrong). In desperation, I went back to the circuit board for inspiration. That’s when I noticed that this particular resistor had a different component code silkscreened on the board. Where the standard component code for a resistor is R, this one was “FR1”.

With a new lead, I started researching component codes. Only to quickly discover that “FR” is not a standard component code. There are several codes that start with F, but none of them represented components that have a resistor-like form factor. Another dead end. My last-ditch thought was … What if “FR” is a combination of “F” for fuse and “R” for resistor? Is there such a thing as a “fuse resistor”?

Turns out, there absolutely is such a thing. Not only do fusible resistors exist, they have a unique color code where the third band can be gold. It should be read like a 4-band code, with an extra fifth band (typically white or black) to indicate that it is fusible. In our case, yellow (4), violet (7) and gold (10^-1) is 4.7Ω of resistance with a 5% (gold) tolerance. The fifth band doesn’t appear to have any standards, and might be manufacturer specific, but if it is white or black, that’s an almost definite sign it’s fusible.

Mystery solved. A mail-order delivery and some quick soldering later, and the little Kawai was up and running like it had never died. You’ll be hearing more about this little Kawai at a future date…