Sony STR-K740P Power Supply Unit

The STR-K740P power supply system consists of a standby board providing standby power to the amplifier. This is usually a 5 V system through a small transformer, and it powers the main microcontroller IC on the front panel. If there are no short circuits detected in the system, then the system allows the main amplifier transformer to receive power. The main transformer manufactured by the Bando Corporation receives power through the relay on the standby board. When the amplifier goes into protect mode, the microcontroller usually cuts power to the main transformer via the same relay.

C803 and C804 are Nichicon electrolytic capacitors with value of 4700 µf/63 V, and D802 is the bridge rectifier RBV-602LF-A.

Here is the standby board. As you can see there is a fuse marked T 2.5.

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