Case from 07/06/2022.
Changing power supply filter capacitor 3300 uf solved the problem.
Author: Provo Electronics
Parts and repair service for audio /studio HI-FI equipment. Mcintosh,Sansui, Kenwood, Fisher,Pioneer, Marantz, others HI-FI gears. Repair service for vintage audio gears. Audio HI-FI equipment repair and restoration service. Arcade games repair. Metal detector Minelab, Whites, Garrett repair , service.
Seattle area.
Case #356465. Sansui C-77 preamplifier repair.
Different output signal level in left and right channel . Unbalanced output signal .
Repair.
Changing double front pot 100k ohm ” volume” solved the problem.
Cleaning did not helped.
One of them for some reason changed value to 60K ohm.
Case #456718. Technics SU-7600 amplifier repair. No sound.
06.11.2022. No sound on both channels.
Pilot light is ON.
Voltage -35 volt and +35 volt from power supply are present. All output transistors are ok.
Relay control transistor TR354 ( 2sc828a) replacement solved the problem.