Play it open: Grundig RTV 650 Tuner amplifier [Receiver] (1969-71)

Grundig's RTV 650 tuner amplifier ("receiver") plays during restoration. In the 56-Volt power supply 2 power Z-diodes (5W) with 60 Volt and 16 Volt were defective. This meant that there was no voltage for either the amplifier or the tuner. In the video the tuner is operated with 2x 9 Volt block batteries to "replace" the 16 Volt power supply for the tuner part. This works surprisingly well (and for a long time) because of the rather low current consumption of the tuner part. The 16 Volt power Z-diode was still on order during the recording. There is a thermo switch beside the heat sink as thermal protection what has always full mains power. So I did cover it with a thick plastic protection during work on the device. The RTV 650 is the successor of the Grundig RTV 600 and was built from 1969-71. It is a quite massive device with a stable construction and "high quality workmanship". Output power: 2x 30 Watt music power, or 2x20 Watt sine continuous power into 4 Ohm. The "Tunoscope" (red/white/red coloured 3x bulb display) facilitates the exact tuning of a received radio station. Final stage with 4x 2N3055 power transistors from RCA. These are still "originals" with the yellow color dots (transistors selected by Grundig and marked with different color codes matching to the eq. driver transistors). Beautiful solid, heavy wooden case in "Rio-Palisander" (Barazilian Rosewood). A "warm sounding" vintage hifi device from late 60'. Speakers used: Jamo dynamic D5E. See also my other, "louder" video about Grundig RTV 650 "play it loud and open" here:    • Grundig RTV 650 Receiver (1969-71) -  play...