Before you begin, read Micah's page and the related links on how to use our equipment (see: Test Equipment).
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Normally precharge will be enabled through a firmware signal from the MCU to the enable pin on the load switch U3. If the firmware is unavailable, this can be powered by connecting a 3v3 source to the enable pin (pin 2). This can be done through another power supply. Before enabling precharge, setup the oscilloscope to read voltage output. There are multiple points of interest to be measured over the duration of precharging and discharging.