Hitachi Amplifier Repairs

Hitachi HMA-8300

200 Watts per channel 1977, this had self-destructed one channel and required a repair. Two output transistors were short circuit (2SA1117\2SC2608) & a fuse blown. There are several small fusible resistors as in the Sansui AU-717 (they are grey 1\4 W resistor size) that were either open circuit or totally the wrong value and needed replacing. One of them was 100 ohm in series with a diode for a c\current source was open circuit, this may or may not have been the cause of its demise.

Hitachi HMA-8300 Power Amplifier Hitachi HMA-8300 Power Amplifier Hitachi HMA-8300 Power Amplifier

This is a class G amplifier, there is a low power amp that works at low power and the higher voltage section 'switches' in when needed +\-40 V, & +\-90 V, the first of this type it is reckoned, but I don't see the point as its weight (24 Kg) and size doesn't give it any advantage over class B amps. The Carver M400 was a better design.