Externally, this looks very much the same as some other devices and is marked 668A on the battery cover, however, it has no built-in torch.
Internally, it is quite different, having only two crystals and three chips.
We'll call this the FM-162 as that's what's silk screen printed on the PCB.
The board is marked FM-162 06113 VER:A BANDV and underneath this writing is a PCB inductor. It uses this and a strip running across the top as an internal antenna before connecting with the signal lead ground. L3 takes the AF to ground. The display is very much like the ChaoYu displays, but above the globe icon is the word 'MUSIC'
Audio is very good on this device, there is no high frequency artifact or high noise floor as found with the CY-6698A type with torch.
| Number | Marking | Manufacturer | Package | Function |
|---|---|---|---|---|
| - | None | Integral | Microcontroller and stereo encoder | |
| IC2 | FS8308-LF  |
 |
TSSOP 16 pin | Low Power PLL Synthesizer |
| IC3 | 070518 24LC02D - 1.8 |
14 pin | Serial EEPROM |
As yet incomplete and in places erroneous schematic from what I've pieced together. Requires Eagle by CadSoft
DOWNLOAD FM-162 SCHEMATIC
Taking the right channel as an example ...
Audio enters via the signal lead. It hits R27 C24 parallel RC pre-emphasis filter. Then it's through R39 before disappearing through to the LCD side of the board. It then goes into IC1 along with the left channel. The left channel is similar.
In the usual way, RF is fed into the ground of the signal lead in order to provide some sort of aerial.
DC Input impedance measures at around 4Mohms so it's much better suited to a line level impedance than other devices with a low impedance input which are more suited to a headphone output.
