First of all, an apology to those following. I haven't updated this at all. I'm going to write a set of back-dated posts so you can read about my progress.

Taking the AWR-1 apart, it seems fairly straightforward. It's pretty easy to open up and once inside there are only a few major components:

• Main PCB (this has all the audio, tuner and control ICs). It also has all the back panel connections
• Transformer
• Battery bay
• Front panel PCB (this handles the display and the buttons on the top of the unit)
• Speakers (mounted into the top half of the unit).

The transformer has three outputs:

• ~3V. I'm unsure of it's purpose at this point. Although I could trace it, I don't need it so I'll probably leave it disconnected.
• ~17V. This is smoothed with a bulk cap then powers the circuitry via a 12V regulator. It's worth bearing in mind that while there are lots of ICs, they're all fairly low power
• ~12V. This is smoothed with a larger bulk cap that powers the amplifier at the back of the unit. It's a Class B amp that's fairly power hungry and it has a large heatsink at the rear of the unit

The transformer is very uniquly shaped. I'm going to struggle with a replacement that fits, so I'll leverage the existing one. It connects to the PCB via two headers with pretty old-school connectors. I'm not sure if I'll be able to source new connectors for them or not. There's no information about this transformer so I've no idea what it's rated for. My guess is that the 3V line is for the internal clock (this is powered by the batteries when there's no power supply) and is very low rated. The 17V line for the ICs is probably not very big either. The only power hungry thing is likely to be the display on the front panel. The 12V line for the amp will be pretty beefy though.

Given what I'm working with, and what I have (some) experience with, I'll use an ESP32 for the main board. It's fairly power efficient (especially when the radio is off) but powerful. Two Xtensa LX6 cores@240MHz and 520K RAM is a lot to work with for this project.

Since I have the footprint, I'll be working largely with through-hole components. This should make it easier to work with and since I'm not going for mass production I don't really need to worry about the manual stages.

I know nothing about amplifiers, having bought them pre-built for years, so this should be a great learning experience!

I know roughly what I need:

• Control (ESP32)
• Data (micro-SD card)
• DAC (probably something pre-built)
• Amplifier (no idea)
• Display (OLED)
• Buttons (these are a mystery, more on that soon)