And here is the Yamaha A-S1200. Finally!
Most people only ever see the front and back:
Only ASR members see more.
First you take off the side panels, they are made from birch it seems, and have a piano black high gloss paint job. Not easy to take a picture:
Then you get to take off the cover, there are screws and some sticky seal. There is a large metal bridge you have to remove as well:
The power amp board has some parts missing, these are populated on the A-S3200 which has even more output power. Sadly we can't see the transistors between board and heat sink:
These capacitors allow the power amp to draw more current than the power supply itself can deliver. The larger their capacity, the better, but they don't come cheap. You have to control inrush currents and charge them at startup, which takes a few seconds once turned on. A microcontroller controls them and you hear all sorts of relays clicking at boot time:
We are looking at the tone controls. Once you move a knob on the front from it's neutral position, relays click and put this stuff into the signal path. The volume is handled here as well, the volume knob at the front is just a dumb 1gang potentiometer, doing it that way ensures perfect channel balance and basically unlimited life:
The power supply for the 12v trigger and right from it the microcontroller that looks over all sorts of operational parameters, voltages, currents, temperatures:
We are looking at the back of the front plate, the violet remote control sensor, below the headphone connector and power switch assembly:
Volume and volume motor (left, the grey round thing), we see the input selector with the PCB on the it's back and one of the VU meters (black plastic case on the right). Conveniently, the VU meter can be zeroed by the potentiometer that has it's own hole in the top:
The front power switch board:
Sadly, the excellent phono preamp was hidden.