DSM/ECU/Reverse Engineering

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Example

Here is an example of record keeping of the components and PCB references I did on a 1.8l ECU I reversed as practice:

Exterior

Top

 MD159561
 E2T33674E
  0607
 Mitsubishi Electric Corp.
 Japan

Side

 9561
 E2T33674E
 Mitsubishi Electric Corp.
 Japan

Interior

Processor

DSM/ECU/TMP76xxx MH6xxx

DSM-ECU Book

EPROM

  • E924

PCB

BOM: DSM/ECU/JE331B988B

How-To

Hardware

  1. Obtain ECU
  2. Take external photographs
    • Mostly for all the numbers and letters/the stickers
  3. Open ECU
  4. Remove PCB
  5. TAKE MORE PICTURES (before you touch anything else)
    • The code on the plug socket
    • The microprocessor
    • The EPROM (if there is one)
    • Any and all visible marking on components
    • The ENTIRE board on BOTH sides
  6. RECORD all components with visible markings, decode resistor values
    • This means a table with the PCB Silkscreen references and the components values
  7. ACETONE bath
    • This is to remove all the conformal coating junk that interferes with reading markings AND the ability to probe, test, and desolder
  8. SCRUB with Toothbrush, Q-Tips
  9. PHOTOGRAPH and RECORD any newly visible information
  10. REMOVE any components with known values:
    1. Electrolytic capacitors can go first
    2. Then any ICs
    3. Resistors with the bands already decoded
    4. Connectors
  11. REMOVE components with unknown values ONE AT A TIME
    1. SMD Capacitors and Transistors are good examples
    2. Remove one, use the Multimeter and/or LCR meter to get values and RECORD them in the table
  12. Eventually you will be left with a BARE BOARD
  13. SPRAY and WIPE DOWN the bare PCB with WD-40 to clean up any remaining conformal coating and junk
    • This preps the board for nice clear photographs
  14. PHOTOGRAPH both sides of the PCB
    • Get ONE photo of EACH side of the PCB
    • Flat
    • In focus
    • Dead-on photos with no perspective error
    • Use a tripod
    • Use lighting
    • Use a remote shutter-release to eliminate shake from the image

Digitization

  1. Do color correction in darktable
  2. Import to GiMP and isolate the Silkscreen to generate a silkscreen layer
  3. Import into Inkscape to create a vector of the copper traces
  4. Use the last two steps to import into KiCad
    • Recreate the PCB
    • Create a schematic from the PCB

Result

  1. A BOM of sorts
    • List of all the components, and their values and locations on the PCB
  2. A Schematic of the electrical connections
  3. A PCB layout
  4. Lots of photos
  5. ROM dumps of all ROM, Internal ROM and EPROM
  6. Disassembly of all ROM, Internal and External

Toolbox

Tools

  • Screwdrivers
  • Tweezers
  • Solder
  • Solder Sucker
  • Solder Wick
  • Soldering Iron
  • SMD/Reflow Air Tool
  • Chamois cloth
  • Multimeter
  • LCR Meter

Solvents

  • Acetone
  • 99% Isopropyl alcohol
  • WD-40
  • Flux
  • Flux cleaner
  • H2O

Camera

  • DSLR
  • Tripod
  • Circular-polarized lens
  • Remote shutter-release
  • Lighting

Software

  • Darktable
  • GiMP
  • Inkscape
  • KiCad