Join me as I repair and service a beautiful and iconic Nakamichi 670ZX cassette deck.

The stand-out point to mention here is that this work took place over six years. That’s right, six bloody years! This is absolutely ridiculous and only acceptable because it happens to be MY Nakamichi 670ZX, part of a collection that includes the incredible Pioneer CT-F1250 I repaired recently and my gorgeous Pioneer CT-A9X. Welcome back and season’s greetings!

I wanted to include a couple of cassette deck articles this year for variety’s sake. Some may wonder why I even have cassette decks or write about them in 2024, legitimate ponderance, for sure. Part of me says “I don’t know” but it’s a bit like playing records or owning a mechanical wristwatch. It comes down to the pleasure of repairing and owning beautiful pieces of equipment like these that will never be made again, and the satisfaction of playing tapes with them.

By the way, I’m not a Nakamichi specialist in terms of offering overhauls on decks like my 670ZX, commercially. I’m a lover and owner of classic cassette decks and I do still offer standard service for machines like the 670, however. I occasionally overhaul decks like this Pioneer CT-A7 but I do so sparingly, knowing few others do this type of work any more. This article is more about sharing an interesting story and perhaps a little cassette deck inspiration 🙂

Background

That I finished this job in December of 2024 when I acquired this deck in late 2017 is a perfect example of how our own equipment is often last in line. There is always so much else to do when running a business and I’m sure others can relate to this. I have many other pieces like this to attend to, my Kenwood L-07DII is another example…

Anyway, I was contacted back in 2017 by a gentleman who told me he had a collection of electronics, parts and equipment he wanted to offload and wondered if I would like to make an offer on it. I got together with my friend Jason (The Speaker Doctor) and we drove over for a look.

The guy had a ton of stuff including this almost pristine but broken Nakamichi 670ZX and some other stuff including broken power supplies and a Lenco turntable. I made an offer to take the lot, which he accepted. I started working on the 670ZX in January of 2018, in my original workshop, so you’ll see some old images from before I set up my big second workshop.

I got lots done initially, including replacing rear belts and idler tyre, overhauling and lubricating the entire mech, fixing stuck meters etc. What stopped me though, and one reason I generally don’t overhaul customer Nakamichi cassette decks was the pain of having to remove and service the seized pinch roller assemblies, one of many issues that can be lurking in decks like this.

After completing everything else, realising the pinch rollers were seized on their pivots as they often are, and knowing the time needed for further disassembly and resolution, I put everything in a box and left it until October of 2024, when I finally pulled it all out again intending to finish the job. That brings us to December 2024, and I finally have finished this epic repair. Thank goodness!

Features

Nakamichi cassette decks generally need no introduction. This iconic Japanese manufacturer made a range of ground-breaking machines over the years, some better than others, but most very lovable in their own way. This 670ZX was a fairly serious ‘Nak’ back in the day, with three discrete heads, variable record-head azimuth, trimmable bias, level and EQ for all tape types, and a lovely smooth mechanism, albeit with a bit too much plastic for my liking.

The 670X was a midrange machine for Nakamichi, but that was far above even the highest-level offerings from many other manufacturers. It perhaps lacked a few features found on other machines, but that said, like the other three head Naks, this deck has features that allow it to make superb recordings and extract the most from cassette tapes. That’s why people spent the huge amounts of money needed to acquire decks like these.

I perhaps have a slightly different perspective on Naks. Some imagine that all Naks are incredible, but the 4xx and 5xx series for example are some of my least favourite cassette decks. What really sets the better Nakmichi decks apart though is how they sound and this is why many folks are still drawn to them, myself included.

Forget the somewhat over-rated Dragon, the only one many seem to remember. The 670ZX, 682ZX, 1000ZXL, ZX-7, ZX-9 and CR-7, amongst others, are some of the finest sounding and performing decks ever made. I owned a ZX-7 years ago but sold it. That was clearly a mistake!

Other cassette decks are easier to work on, less prone to 6-year-break-inducing pinch-roller seizure and idler tyre issues and have more robust head designs. Still, the pressure-pad-lifting, dual-capstan, discrete three-head Nakamichi designs really do extract the max from cassette tapes.

Nakamichi 670ZX Specifications

Adapted from and courtesy of HiFi Engine

Type: 3-head, single compact cassette deck

Track System: 4-track, 2-channel stereo

Tape Speed: 4.75 cm/s

Heads: 1 x record, 1 x playback, 1 x erase

Tape Type: type I, type II (CrO2), type IV (Metal)

Noise Reduction: Dolby B

Frequency Response: 10Hz to 22kHz  (Metal tape)

Signal to Noise Ratio: 66dB  (Dolby B)

Wow and Flutter: 0.04%

Total Harmonic Distortion: 0.8%

Input: 50mV (line)

Output: 1V (line)

Dimensions: 482 x 143 x 340mm

Weight: 9kg

Accessories: optional remote control

Year: 1979

Service & Repair

I’ve probably bored you to death with the history so I’ll keep further details reasonably brief and mostly visual. In a nutshell, repair and service on this Nakamichi 670ZX occurred in three stages:

• Mech disassembly, service, rear belts and idler replacement (2018)
• Seized meter removal and service (2018, 2024)
• Pinch roller removal, service, front belts replacement, transport shut-off lamp replacement, reassembly (2024)

Let’s go!

Initial Work in 2018

At this point back in 2018 I stopped and got busy again with a whole new series of customer jobs for the new year. It took me more than six years to come back to this job but I’m glad I did. Let’s continue.

2024 Continuation

And that, my friends, is this job completed. As time allows, a full electronic adjustment will follow.

Results

Well, what an epic and albeit extended repair this was, but well worth it as I’m sure you’ll agree. This lovely old Nakamichi 670ZX now runs perfectly once again and sounds fantastic. When I can be bothered, I’ll complete an electronic calibration, but for now, this one will go back into my collection.

I do offer general service of Nakamichi cassette decks, but I want to reiterate that the deepest service work you see here is unfortunately not something I have the time or energy to offer as a general rule. I find that the amplifier and turntable work I do is more than enough to keep me busy without adding major cassette deck overhauls into the mix.

Once again, thank you for visiting and I’ll see you again before Xmas!