Recently, two friends with lovely vintage Yamaha CA-610 and CA-710 integrated amplifiers sought my assistance to have them repaired. One was dead, the other was not working well.
The Yamaha CA-710 had blown one channel. One of the original output devices, a Sanken 2SA745, had a collector to base short and it had taken out one of the driver transistors.
The CA-610 was exceptionally dirty and greasy inside and working intermittently due to this contamination of switches and rotary controls.
I fixed both of them and their respective owners were extremely happy, they had probably both not sounded so good in years!
Full writeups coming soon…