Long story short, I managed to damage my fresh built QMX+ by trusting a USB-C PD power supply too much... The symptoms are that I'm still able to power it up and the display is normal before SMPS kicks in. When the controller starts to use SMPS, the LCD goes all blocks so I guess the 5V rail is damaged. Visual inspection shows 74ACT08 is damaged as well. The terminal application is still working (so 3.3V is fine?), but if I try to access the hardware diagnosis function, QMX+ crashes and the USB connection is lost. The steady power consumption after SMPS bootstrap is about 22W so something is probably shorted.
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I have an unbuilt QMX+ board that I can take components from. Really appreciate anyone could help me narrow down the components to check/repair. I was trying to use QMX+ SSB to work some WPX SSB contest stations... Really wish I could still make it... ?Many thanks!
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73 de N6HAN Zhenxing Han
