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, we found ourselves with a dead Kawai WK40 keyboard in the Mechlab. After some poking and probing, we 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 we attributed to it being an older keyboard and component-design drift over time. In any regard, we felt we should replace it and see if that reanimated our keyboard corpse.

Because the multimeter readings were inconsistent, we needed to figure out the value of the resistor. Memorizing resistor value color codes sounds about as engaging as cataloging toe nail clippings, so we needed to rely on internet resources to determine the replacement value. This is where our mystery deepened. It was at this point that we realized that the third band in a 5-band code can’t be gold. And that the fifth band can’t be white. Yet, we 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.

We checked for older standards, but still came up confused. We checked to see if there were different color code standards in Japan (where Kawai is headquartered), but found nothing. We 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, we went back to the circuit board for inspiration. That’s when we 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, we 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. Our 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…