Repair of a Vintage Hitachi HA-5300 Amplifier

Repair of a Hitachi-HA5300 Amplifier

I’ve repaired a couple of Hitachi HA-5300 amplifiers so I’m familiar with how they work. Faults I’ve repaired on them include distorted sound, a failed speaker relay, and a blown bulb that illuminates the numbers around the volume control.

If you have one that needs repairing please contact me for a repair quote. Amplifiers can be sent to me or dropped off.

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This old Hitachi HA-5300 needed a repair as it had distortion on one of the channels.

Repair of a Hitachi-HA5300 Amplifier

An interesting old design as it uses a class E amplifier stage that Hitachi call Dynaharmony. Back when this was on sale a lot of amplifier manufacturers were experimenting with different types of output stage and this is one of them.

The Hitachi amplifier uses proper power transistors for the output stage rather than an obsolete STK module that ended up in most amps of the time.

Hitachi HA5300 for repair PCB view

Some components had drifted out of value causing distortion on the output so were replaced along with resetting the output stage idle current (bias).

The oscilloscope image below shows the output distortion at 1KHz. This is classic amplifier crossover distortion.

amplifier crossover distortion

If you need a Hitachi HA5300 or a vintage amplifier repaired please contact me. Amplifiers can be shipped to me for repair.

Electronics and Audio Repairs in Nailsworth, Gloucestershire