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
Datasheets
Kenwood TH-D74A Datasheet - IC-701 - DRAM
Kenwood TH-D74A Datasheet - IC-702 - omap-l138