A technically very interesting car radio from 1967. In the world of vintage car radios, the Autovox Concorde Serie 2000 from 1967 is a particularly interesting unit, often installed in cars such as the Lancia Fulvia. Recently I was entrusted with one to restore, and the work turned out to be very interesting both from a technical point of view and for the solutions adopted at the time.

The Autovox Concorde Serie 2000 is a very advanced example for its time. Produced in 1967, this car radio stands out for being completely solid state and for using an electronic automatic station search system. Tuning uses varicap diodes and three logic integrated microcircuits produced by SGS, Società Generale Semiconduttori, responsible for managing station selection and the automatic tuning operation.

The operating principle of the automatic tuning is based on a voltage ramp controlled by the internal logic. By pressing the right knob, the radio starts scanning the band and the tuning progressively moves along the frequencies. When a valid station is detected, the ratio detector stops the ramp and locks the tuning at the correct point. The search occurs in only one direction, from the lower end toward the upper end of the band.

A particularly interesting element of this car radio is represented by the three metal integrated circuits marked SGS AUTOVOX, specially made for this device. In the absence of the complete schematic it is not easy to determine precisely all their functions. In case of failure, moreover, replacement becomes problematic because these components are practically unobtainable and can only be recovered from another unit used as a donor.

This unit was delivered to me completely silent. An initial diagnosis revealed the failure of a 470 ohm resistor in the amplifier section, which was immediately replaced.

It was then necessary to replace the faulty electrolytic capacitors in order to restore correct operation of the car radio.

Another critical point concerned the four AF117 germanium transistors. These are four terminal transistors well known for reliability problems that can appear over time. In this case they were all faulty. Replacing them with NOS AF117 would not have been a truly reliable solution, because even apparently new components can present the same defects. I therefore used BC251 silicon transistors that I had available, which proved suitable for the purpose.

The replacement was successful and the car radio started working again regularly from the very first power up test.

Overall, the repair of this Autovox Concorde Serie 2000 made it possible to bring back into operation a technically remarkable car radio, which clearly shows the level reached by automotive electronics already in the late 1960s. These are devices that still maintain considerable historical and technical interest today, especially for those who appreciate the particular circuit solutions adopted in those years.

To observe more closely the result of the repair, a demonstration video of the Autovox Concorde Serie 2000 in operation is available below. In the video I quickly move from one station to another to avoid continuous playback of music and instead focus on talk radio stations.

Functional recovery of a Concorde 2000 that could not be repaired

In another Autovox Concorde Serie 2000 that was entrusted to me, unfortunately one of the custom SGS integrated circuits was faulty and, since no replacement or complete schematic was available, traditional repair proved impossible. In these cases the only sensible solution was to recover the radio from an aesthetic and functional point of view, maintaining its original appearance but completely replacing the internal electronics. I therefore removed all the original circuitry and also eliminated the separate power supply block, which had become unnecessary.

Inside the chassis I installed one of my FM modules with modified firmware, so that tuning was controlled by a variable voltage from 0 to 5 volts obtained directly from the wiper of the original tuning potentiometer of the radio, which in fact was originally designed with a potentiometer for frequency adjustment. Next to the FM module I also installed a small audio amplifier based on TDA2030.

In this way the radio completely maintains its external appearance and original controls, but with much more stable and precise tuning and with audio power increased from about 2 watts originally to about 8 watts RMS, making it perfectly usable even today in a vintage car.