Grundig RR 720 [Grundig]

Grundig RR 720 – a cassette recorder with a history

Sometimes a single photo in a magazine is enough to bring back a memory that had been buried somewhere for decades. That’s exactly what happened to me with the Grundig RR 720. An article featured a picture of a similar device, and suddenly it was back: the memory of the cassette recorder that my brother and I used in the 1980s. The orange fade-in and fade-out button in particular is etched in my memory – we used to press it constantly whenever we were recording music from the radio.

Unfortunately, I couldn’t find any photos from that time. But the memory was vivid enough that I set out to find an RR 720. After a while, I came across one on eBay, and I’ve had it ever since.

More than just nostalgia

For me, the RR 720 was more than just a radio recorder for music. Before the ZX Spectrum arrived at our house, I already had a ZX81, and a cassette recorder was simply essential for both computers – nothing worked without it. I used it to load countless games and, just as often, to save BASIC listings that I’d painstakingly typed out from computer magazines. Anyone who’s experienced this for themselves knows that a cassette recorder that loaded and saved reliably was almost as important as the computer itself back then.

The series

The RR 720 is part of a four-model Grundig range launched in May 1981: the RR 621, RR 640, RR 720 and RR 750 share the same casing and basic technology, but differ in terms of their features. The RR 621 and RR 640 are the simpler mono versions. The RR 720 and RR 750 offer stereo capability as well as an additional Preomat module for automatic level control during recording. The RR 750 also features a clock module with an alarm function. My unit, the RR 720, is therefore the stereo version without a clock – just right for my purposes, as this is exactly the model we had back then.

The situation and what still needed to be done

Als das Gerät bei mir ankam, ließ sich schon nach kurzem Test erahnen, dass vor mir schon einmal jemand Hand angelegt hatte – nur nicht besonders sorgfältig. Ein Techniker des Vorbesitzers hatte offenbar die Antriebsriemen ersetzt, allerdings nicht durch passende Originalriemen, sondern durch einfache Gummibänder. Das Ergebnis: Aufnahme und Wiedergabe liefen spürbar zu langsam, was sich beim Vergleich mit einem zweiten, korrekt laufenden Kassettenrekorder eindeutig nachweisen ließ. Zusätzlich hatte eine der Andruckrollen einen Riss, und der Aufnahmeweg vom Radioteil zum Verstärker war unterbrochen, sodass sich zwar der Empfang, nicht aber Radiosendungen aufnehmen ließen.

With the help of the original Grundig service manual from 1981 – including circuit diagrams, part numbers and calibration instructions – it was possible to pinpoint the problem and have it rectified by a technician: the correct belts instead of rubber bands, a new pressure roller, and the broken connection in the recording circuit was repaired. Since then, the device has been running at the correct speed and is once again recording from the radio.

Outlook

The device is heading to the museum, where it will be used to recreate my original setup – the ZX Spectrum 48K and the Grundig RR 720, just as they were back at our house all those years ago. I’ll describe in a separate article how I got the recorder working again and connected it to the Spectrum.