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I got an amp in to repair that was the peak of late 80s high-fi performance in the USSR. It is solid state and rather complex with over 150 transistors and ICs with layered pc boards. It is "Корвет 200ум-88с" or in Latin characters Corvette 200UM -88S.
I hear of people speaking of reverence for this amp and how great it sounded but never worked on one. This one had problems with both channels. Working in it was a challenge since I had no schematic and the parts were all Russian made parts from that era. The unit is packed, little room for even air circulation let alone getting my fingering to it. It consists of 12 pc boards and hand wired connections between the boards, with no connectors to unplug and get access to the boards. After working on it for a while in frustration the thinking of the designers started to reveal itself and I had a little more respect for it. After I got it working I found a schematic on a Russian language audio forum.
It actually worked well but not in the same class as better amps from Japan and the US of the time. Noise floor was mostly 1/f noise, no hum to speak of, and it generated 200 watts per dual mono channel with about 80db signal to noise ratio. The rear label suggests 800 watts total into 4 ohms but I did not verify that. The protection circuit monitors temperatures, offset in several places current and has the protection circuit mute the front end, drive, and removed both the ground return and speaker.
I hear of people speaking of reverence for this amp and how great it sounded but never worked on one. This one had problems with both channels. Working in it was a challenge since I had no schematic and the parts were all Russian made parts from that era. The unit is packed, little room for even air circulation let alone getting my fingering to it. It consists of 12 pc boards and hand wired connections between the boards, with no connectors to unplug and get access to the boards. After working on it for a while in frustration the thinking of the designers started to reveal itself and I had a little more respect for it. After I got it working I found a schematic on a Russian language audio forum.
It actually worked well but not in the same class as better amps from Japan and the US of the time. Noise floor was mostly 1/f noise, no hum to speak of, and it generated 200 watts per dual mono channel with about 80db signal to noise ratio. The rear label suggests 800 watts total into 4 ohms but I did not verify that. The protection circuit monitors temperatures, offset in several places current and has the protection circuit mute the front end, drive, and removed both the ground return and speaker.
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