On Thu, Apr 3, 2025 at 10:25 AM, Stan Dye wrote:
Maybe Ludwig has more ideas.
Not so much in the moment. Maybe I will do a test using a cheap evalboard containing a STM 32. I want to check what will happen in case of VDD = 4.5 V or so. Will it stop? Yes, if not it's no proof for the particular QMX+. But if it stops it would point to raising VDD first and stopping the STM32 after this and not vice verse.
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It is not likely a capacitor issue; their failure rate is very low. ?It is more likely a temperature issue, where something is thermally expanding just enough to cause a short, or a component is failing and shorting as it heats up, or a 'cold' solder joint is changing its connectivity.
This is also my favorite.
There is also a lower possibility for an unreliable solder joint for one or more IC pins.
And there is a lower possibility for failure inside an IC. Lets assume the TXCO or IC202 is stopping when heat a bit up. This would stop the controller and the SMPS couldn't work right.
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It would be nice to use an oscilloscope to check the clock signal before and after IC202 in "frozen" state.
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It maybe interesting to see what happens when TCXO and IC202 are cooled a bit or heat up a bit during work. Would the period until the controller stops be significant longer / shorter?
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73 Ludwig
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