The Amplifier Modules

To access the amplifiers, I had to remove the two wooden handles by the sides first. The entire front panel can then be lifted, exposing the amplifier modules and a spring reverb at the front.

Apart from some dust accumulated over the years, the amplifiers look fine. No signs of burnt components. The driver boards are mounted onto the heatsinks whereas the TO-3 power transistors are on the base. They are coupled to the heatsinks by aluminum L bars.

The power supply is located at the right. The secondaries of the transformer is at 31-0-31VAC (unloaded). It is connected to four rectifiers arranged in Full Bridge. The two blue cans are the filter capacitors. In front of them are two 15V zener diodes that power all the op amps.

The Mixer Section

This is the underside of the front panel. On the left is a large pcb that contains the entire seven channels. The smaller pcb on the right is the master section and graphic eq. The brown pcb on the lower right is for the LED display.

All inputs from the back panel are routed to the mixer pcb by cables. Signals from master pcb are then routed to the power amplifier modules down on the base plate.