SABA 9241 receiver (made in Germany, 1977-79)

Imgur gallery: https://imgur.com/gallery/saba-9241-r... This was one of the most painstaking repairs I have ever done. I got very lucky that the Germans have forums where people actually know what they are doing. Without the dedicated SABA forums, I don't think I would have repaired it in "just" a month. The faults: • All 8 power transistors – burnt out (and not only that, but someone in the past had already tried to change them, so even the burnt ones weren't original). • About 10 more medium and small-signal transistors on the audio path – replaced. • Various burnt, carbonized resistors. • The bias potentiometers for the power stage – one completely destroyed, the other set completely wrong (10 volts instead of 0), which is probably why the replacement power transistors overheated and blew up. • A power bridge rectifier for one audio channel – destroyed. • The PCB traces from that bridge – burnt, carbonized, broken. • A dying selenium bridge, replaced. • The potentiometer for the varicap tuning voltage – massively corroded, destroyed, replaced. • The CA3189 IC (FM intermediate frequency amplifier) – completely dead, replaced with an HA12412 IC that I had salvaged from spare parts. • The TDA1029 IC – partially defective. I ordered replacements online and got very lucky to still find some 33 year old NOS After I replaced it, switching worked properly. • Electrolytic caps replaced. • The switching muting circuit was out of calibration (the speakers would pop with every input switch). • The stereo decoder wasn't working, so I adjusted it. Since I have a similar one from a SABA 9260, I pulled it out of that receiver, put it in this one, swapped them, and was able to isolate the cause quickly. After adjusting some potentiometers, it recovered. • Various other necessary adjustments. • Many cold/cracked solder joints. • The transformer had a broken plastic bracket; it was practically floating, hanging by its wires. Somehow, by a miracle, the frequency counter/display module survived. Another miracle: the TCA530 IC, the varicap voltage stabilizer, works properly. Plus, I had to put it in the bathtub under the shower for about 15 minutes to wash it with detergent... there was no other way to get rid of the grime inside. I am not a big fan of such "showers" for electronic equipment, but here the situation was far too bad. As a side note, regarding signal switching: everything is done using TDA1028 and TDA1029 integrated circuits. There is no mechanical switching in this series of receivers. This is all well and good—more reliable than mechanical buttons with contacts that can oxidize—until one of those ICs fails, as was the case with mine. Another piece of trivia: they were some of the most service-friendly devices when it comes to maintenance. Although they have rather cramped chassis, almost everything is modular, and the modules can be removed and mounted on the back of the main board, making adjustments and troubleshooting extremely easy. The new power transistors are Toshiba 2SC5198 and 2SA1941. I measured the voltages at the amplifier outputs on an oscilloscope using 4.7-ohm power resistors and converting everything gives me somewhere around 106 undistorted watts. Let's call it 100, but that's more than enough, considering the service manual specifies 2x80 watts. The heatsink doesn't get hot either; at worst, it becomes lukewarm. In fact, the entire back of the receiver is an aluminum heatsink. Yet, the receiver still gets warm. Due to the 4 dial bulbs—about 2 watts each—placed very close to the board containing the voltage stabilizers, a lot of heat is generated in that area. And finally, a few words about the reception quality – excellent. The 9200 series receivers had some of the best tuners of that era. Nothing to complain about, very sensitive. I also slightly extended its FM band coverage up to 106.1 MHz by adjusting the voltages for the varicap diodes. Even the AM section works very well if I connect a longer wire to the antenna jack. The audio section – a score of 10/10, with my compliments. The sound is top-tier, and anyone who has anything to say to the contrary either hasn't heard such a device, has bad speakers, or hasn't serviced it properly. Or they are an audiophile snob who thinks that if it doesn't carry a price tag of tens of thousands of euros, it doesn't sound good. The adjustment of the "loudness" function is done in steps, allowing the user to choose the intensity according to their own preference. And the aesthetics – the front panel cleaned up surprisingly well; only a few minor scratches remained. It looks good, ready to be put on the shelf now. The case should also be repainted; maybe I'll get around to it one day. In conclusion, what more can I say? It was a lot of work, but it was worth it. These 9200-series receivers are some of the highest-performing and most pleasant-sounding units ever produced by the West German Hi-Fi audio industry.