I am debugging my power supply using an oscilloscope. I have uploaded pictures of my setup, including oscilloscope reading, wiring (just power and ground with jumpers), and the power supply specs. The power supply is supposed to output 5V 10A DC, but the oscilloscope at 1X is reading ~480mV. Is this power supply bad, is there something wrong with my setup, am I reading the oscilloscope incorrectly, or is it something else?

osc reading


power supply specs

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    \$\begingroup\$ Are you using a X10 scope probe? If so, your 488 mV would really be 4.88 V. Use a multimeter to verify the voltage. \$\endgroup\$ – Peter Bennett Mar 8 at 5:03
  • \$\begingroup\$ It's from this oscilloscope, and I think the scope probe is X10: amazon.com/gp/product/B07XBL4BTL/… \$\endgroup\$ – errolflynn Mar 8 at 5:25
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    \$\begingroup\$ If you tell the scope you are using a 10X probe, it will display the actual measured voltage. Usually in the input setup menu but that scope has a button. \$\endgroup\$ – ScienceGeyser Mar 8 at 6:25

Agree about the probe.

Also, switching power supplies, especially low-cost ones like yours, usually have a minimum load requirement. 10% is a common requirement "to stabilize the magnetics" (ooooold app note phrase). Without this, the supply is not guaranteed to maintain regulation.


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