Power Supply DC-DC Converter

The Sony TC-152SD has a complicated power supply consisting of a DC-DC converter module, which generates +24 V, -24 V, +9 V rails from 6 V. Whether the six volts came from the four 1.5 V batteries, or from the mains transformer, the module has to generate the various voltage rails if the unit is to operate, and if the module fails, then the unit will not work. One advantage of a DC-DC converter is that it does not place a great load on the batteries, but instead draws current in very small pulses thereby prolonging the life of the batteries.

Circuit Diagram of Power Supply

The output from one bridge rectifier feeds around six volts to the DC-DC Converter, while the second bridge rectifier feeds power to the speaker amplifier circuit. The 10 mH and 470 mH coils provide filtering to the power rails based on the oscillator frequency of the DC-DC module.

It is interesting to note that the live and neutral from the mains socket connect directly into the primary windings of the step down transformer; therefore, the transformer isolates the high voltage. Later versions of this model had only two pin sockets, without the earth pin.

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