Luxman Amplifier Repairs
This would loose a channel, found the tone controls needed switch cleaning and the quiescent was about 250 mA per channel. The pre-set needed setting correctly to about 30 mA. The knobs would rotate as the inner bushes had become loose. Sounded fine for an early 70's amp.
The RH power amp had 50 V DC on the output, the o\p transistors, drivers and a few resistors needed replacing. The o\p transistors were 2SD218 and it's complement only rated at 60W, a bit low as it is a 80 w\ch amp. I replaced the 50 V 100 µF and 25 V 470 µF electrolytes on the power amp board as the were getting warm, not surprising after 40 years.
Another classic from 1975, 75 Watts and a price tag of over £300! This had no o\p, each power amp plugs into a main board - great idea! The drivers and o\p transistors were s\c, the drivers are TO66 types that are not available and were replaced with TO220s from RS. Cut down heat sinks (T0220's) were fitted to both sets of driver transistors as they run hot without, o\p transistors were replaced using MJ15015\16.
All the preamp section transistors needed replacing in this receiver, the tone controls were doing strange things, boosting hiss at the centre position and one channel varying both channels?