Optonica SM-4100 Inside Look

This amplifier was in a right state when I received it, and it needed some loving restoration. Luckily, it came into my hands and now it is worth its weight in gold. Somebody had cut the power cord indicating that an engineer of sorts had given up. What a shame being cut-off in your prime I thought :-)

These Japanese relays are generally very reliable, even a 30-year old one such as this is still in its useful life period. The problem usually occurs when amateurs remove them for testing.

The input selector switch is right at the back, and there is a connecting rod going to the front control knob.

The power supply circuitry consists of these Nichicon capacitors.

There is this lovely mains transformer, and interestingly it is a low profile one with copper shielding across the windings.

In the following sections of this multi-page article, there are more photographs showing the inside of this amplifier. Sit back, relax, and enjoy them all. In addition, if you like the article then donate some money to the Holocaust Memorial through the donate page.

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