Re: QMX+ failed with power issues on first power up
|
The 3.3V SMPS and the 5351 are definitely too hot! An output(s) of the 5351 might be shorted to ground, or the component may have failed.
The inductor L201 gives you an opportunity to assess whether the 5351 is drawing too much current. With the power off,? measure the L201 resistance. With the power on, measure the voltage across it and calculate the current through it. That current is the sum of 5351 and TCXO current demand, so you don't have a pure isolated reading.? Still, knowing that the TCXO does not draw much, and checking the spec for 5351, you can get a sense as to whether the current draw is out of bounds or not.
Another useful check is to look at clock signals CLK0, CLL1, and CLK2? with a scope and see if the signals are the expected frequency and level.
JZ
3.3v power supply around 50C
processor 30C
5351 34C?
|
