Repair-Off: 10 Month Old Fitness Tracker vs. 55 Year-Old Radio

Note: this post first appeared on the Fight To Repair, a newsletter for the right to repair community. You can subscribe to it at:

One morning earlier this summer our golden retriever, Bruno, chomped through the power cord to a ca. 1965 KLH Model 21 radio. Let me be clear: this isn’t a precious object, exactly. But it is a prized possession. For one thing: I really love radios – they’re cool devices and the 20th century’s Ur consumer electronic. By the early 1930s, 60% of American homes had one. And, for more than a century now, radios have reflected and embodied changes in technology, aesthetics and consumers’ taste. They range from the cabinet-sized vacuum tube powered monstrosities of the 20s to the D-battery powered, shoulder mounted boom boxes of the 1980s, to today’s sleek Bose countertop radios.

The KLH Model 21, introduced in the early 1960s, was the Bose of its day – a small, stylish, countertop radio with a big sound. (Also like Bose: it was manufactured in Massachusetts.) So, when a friend was putting a Model 21 up for sale – a single owner unit purchased half-century before – I snapped it up. And then, a few months after that, Bruno decided to lunch on its power cord.

Long and short: that “decision” on Bruno’s part rendered my Model 21 useless and set me on a path to fix the radio. In the process, I got a very useful object lesson in how much has changed in the last half century when it comes to our ability to service and repair our stuff. That’s what this post is about.

Got Power Cord?

My first task in fixing my radio was, of course, to find a replacement cord. Despite the advanced age of the Model 21, it’s really not hard to find parts. Sites like have forums for all different kinds of radio models. Got a dog who chewed through the power cord on a 50 year-old tabletop radio? There are plenty of experts on these forums who can help you navigate the repair and get your hardware working again. Then there’s eBay, which is paradise for anyone looking to buy an obscure replacement part, and where I found a white power cord harvested from another KLH unit that was nearly identical cord to the one Bruno chewed through. (Thanks jmaudioshop!)

Repairs made easy

Replacement power cord in hand, the next thing I needed to do was figure out how to replace the cord on this particular model. Fortunately, KLH made that job really easy: publishing a detailed Service Manual for the Model 21 that accompanied each new device. The service manual contains detailed schematics and other documentation of the radio’s inner workings – basically anything that owner would need to keep the tabletop radio working.

The KLH Model 21 came with a detailed service manual that included schematics and part identifiers.

That included detailed diagrams and schematics that explained the different components of the Model 21 and its inner workings. With the information in the Service Manual, I could glean the layout of the Model 21 and its workings without even removing the chassis!

KLH Model 21 schematic from service manual.

Amazingly, the service manual even included a diagram documenting the voltage and resistance for each connection to the audio amplifier board. Much more information than I needed but…wow.

I’ll also note the perfunctory language on the schematic about the absence of “user serviceable parts,” refraining from opening the device and getting “qualified” (note: not “authorized”) service personnel to fix it. What’s ironic is that, even while including that legalese, KLH provided owners – or those “qualified personnel” with all the information needed to repair the device themselves.

Diagram from KLH Model 21 Service Manual showing voltage and resistance for each connection to the Audio Amplifier Board.

Name That Fuse!

Of course, once I had the chassis off, figuring out where the cord went was straight forward. I removed the remnant of the previous cord and soldered on its replacement. Still, the Service Manual proved useful to me. The space around where the power cord attached was pretty cramped and, while I was threading it through and soldering it into place, a small fuse that was an original part detached and needed to be replaced.

What exactly was this 50 year old part? A 1/4 AMP Slow Blow fuse, according to the Service Manual. With that handy information, I was able to order a replacement fuse, solder it in to replace the fuse that broke and get my Model 21 working again.

Ta da! Mission accomplished!

FitBit: Repair = Replace

Now let me contrast that with another recent “repair” that fell into my lap – this one much more straightforward but, as it turned out, much less so: my daughter’s 10 month old FitBit Charge 4 watch and fitness tracker…