Page 8 - Testing Electronic Components
P. 8
Modern equipment consists of two grounds, one of which is a hot
ground while the other is a cold ground. Hot ground is in the primary
side of a switch mode power supply while the cold ground is the
equipment ground.
Be careful when taking voltage measurements around these grounds. For
example, if you want to check the primary circuit of a power supply with
power on, always ground your meter or scope to the hot ground, while
check the secondary side using the cold ground.
If the Hot ground is not used and you use only the cold ground, the
voltage measurement might not be correct and it may destroy your meter.
One way to prevent this is to use an isolation transformer.
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