On Sat, Mar 29, 2025 at 04:19 PM, Zhenxing Han N6HAN wrote:
The steady power consumption after SMPS bootstrap is about 22W so something is probably shorted.
This would mean 1.8 A @12 V! To much and dangerous for the QMX.
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the display is normal before SMPS kicks in
What do you mean by "normal"? Before SMPS is working the display should be blank and dark.
When the controller starts to use SMPS, the LCD goes all blocks so I guess the 5V rail is damaged.
How do you know the controller is working and starts the SMPS in this state?
When the controller starts to use SMPS, the LCD goes all blocks so I guess the 5V rail is damaged.
Strange. In some failure situation going to Diagnostics may reduce input current. Do you know your supply voltage every time?
Visual inspection shows 74ACT08 is damaged as well.
When seeing a damage something very bad was happening.
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trusting a USB-C PD power supply too much...?
Could you tell a bit more about? Is it important it was USB-C? How did you feed your QMX by the USB-C PD power supply and how did you feed it later?
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73 Ludwig
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