Hello,
Thanks to RoxsAndy, its discovered that FTDI part design in box has few flaws, thus preventing box to work properly.
Problems caused by this design error were :
- Unstable speed
- Impossible to read flash from phones
- Communication glitches
To fix those problems, please do the following:
- Swap resistors R8 and R9
- Short circuit R9 to C10
- Solder capacitor 22pF between R7 and pin 8 of U3 IC
- Solder 22pF capacitor between R1 and R2
Please download attached photo of PCB with detailed instructions.