The complete chassis was cleaned and polished with carnuba wax. Scratches and dents were removed. Then module by module and component by component were checked as well as all solderings, all contacts. All potentiometers and switches were cleaned and preserved, tubes were measured on Funke W20, Each single capacitor was measured. Resistors, diodes, filters and opto couplers were checked for value and function and exchanged where differences appeared.
The opto couplers are a weak point. They consist of 2 elements, a light emitter and a light sensitive resistor. We checked all of them and replaced the whole coupler which is made by our labs in premium quality better than it was.
The rc-module as the time constant, responsible for deemphasis was changed according to the schematics. Voltage was changed as indicated in the circuit diagram, a foil shielded high end power cord with ground was mounted. Finally the set was adjusted and aligned for high sensitivity and selectivity, narrow and wide reception, muting threshold, stereo-sensitivity, lowest THD and flat frequency response. Both front panel glases were renewed, the DG7-32 oscilloscope tube is new (Amperex). The tuner's technical data are now equal or better compared with its first delivery.
Audio Classics
The opto couplers are a weak point. They consist of 2 elements, a light emitter and a light sensitive resistor. We checked all of them and replaced the whole coupler which is made by our labs in premium quality better than it was.
The rc-module as the time constant, responsible for deemphasis was changed according to the schematics. Voltage was changed as indicated in the circuit diagram, a foil shielded high end power cord with ground was mounted. Finally the set was adjusted and aligned for high sensitivity and selectivity, narrow and wide reception, muting threshold, stereo-sensitivity, lowest THD and flat frequency response. Both front panel glases were renewed, the DG7-32 oscilloscope tube is new (Amperex). The tuner's technical data are now equal or better compared with its first delivery.
Audio Classics
