Clock Radio
I picked up a clock radio...
I picked up a clock radio at a garage sale last weekend. Here it is, partially reassembled for demonstration purposes.
My goal is to repurpose it into a battery powered bluetooth speaker. I took it apart to see how it's constructed.
It's a typically Sony design. High quality, and a little too clever by half. The bottom board is single-sided through-hole, and handles power and a bunch of buttons. The main board is a single-sided SMD/through-hole hybrid, which is typical of consumer A/V design.
It's a simple design, but they aren't making cut rate garbage. You may have noticed the 1000uF power capacitor on the bottom board is a Nichicon. There are a couple Rubycons too. Those are top quality capacitors. They've economized with smart design. There is only one kind of tactile button used on the board. The side buttons use levers molded into the plastic to actuate buttons on the board. The design also uses only one type of screw for both board mounting and securing the shell. And the single sided hybrid board allows moderate complexity with cheap wave solder manufacturing (though they certainly could have made it cheaper by using one PCB).
The power cable is also non-detachable, which is super annoying, but they probably did it so that the power cable doubles as an integrated antenna.
The unit does work, but it had a sticker on it that said "FM only". It turns out that was an easy fix. One of the little flying wires off of the coil was broken.
In addition to this, a couple of retaining clips were broken off, suggesting it was dropped at some point. The waxy looking stuff is in fact wax. It seems to be some kind of paraffin. I'm not sure if it's there as a protective conformal coating or it melted off the coil. The coil is fully encased in the stuff.
For the purposes of repurposing, I think I'm going to reuse the bottom board and hack in a USB connector for charging. Then I'll design a new main board with all the switchgear in the same location so I can just drop it in. Probably use one of those cheap OLED displays instead of the LCD. And I think there's juuuuust enough space in the back curve to stuff in an 18650 cell.
Also a spring fell out when I took it apart and I can’t tell where it’s supposed to go.