Kenwood TH-D74A
Teardown Video
6 minute video @ 3x playback speed showing full disassembly of the radio with commentary, full length video with no audio here.
Teardown PCB Pictures
Processor Board Top
Processor Shield Removed
Processor Board Bottom
JTAG Pinout
Transceiver Board Top
Transceiver Board Top Zoom 1
Transceiver Board Top Zoom 2
Transceiver Board Bottom
Transceiver Board Bottom Zoom 1
Transceiver Board Bottom Zoom 2
FM Radio Module Top
FM Radio Module Bottom
Modules and Interconnects
LCD Front
LCD Back
FM Antenna Front
FM Antenna Rear
Interconnect Top
Interconnect Bottom
Channel Selector
Mechanical Pictures
Front Case Interior
Metal Frame Front
Metal Frame Back
Metal Frame Connector Side
Metal Frame Button Side
Metal Frame Top
Rubber Gaskets
Screws and Knobs
Reverse Engineering Efforts
High level goals
- Obtain a copy of the firmware for analysis/modification
- Understand how the radio works and what test ports are available internally
Obtaining firmware
- Determine routes of attack
- JTAG Port
- Serial Port
- Hardware attack - Remove Flash Memory and read directly (possibly encrypted)
Initially the radio was opened and wires were soldered to some test points and an interesting PCB footprint that I suspected was JTAG as seen in the video below.
There is also a serial port labeled SCTX and SCRX, both of these lines appear to be transmit only from the top CPU board down to the bottom transceiver board. As the radio is tuned from one frequency to another the SCRX line has a lot of activity, when the transmitter is keyed up the SCTX line has activity. Here is a sample of what is seen on the SCRX line.
| SCRX |
|---|
| J0000 |
| K0000 |
| G0283 |
| `0 |
| G1283 |
| B06EE14 |
| B0A03CE |
| B0C0028 |
| B11E960 |
| B180000 |
| B140000 |
| B1C2812 |
| B200018 |
| B280A68 |
| G;7:3 |
| K1900 |
| a7:6 |
| B1C2C12 |
| B140000 |
| B1C2812 |
| B200018 |
| B280A68 |
| F41 |
| J01 |
| G;7:3 |
| `0 |
Understand how the radio works