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I'm suspecting my voltage regulator is defective because I made the same circuit twice with the exact same components but this time, the battery voltage of 7.2V is being passed to the entire circuit when the rest of the circuit should only get 5V.

So when a voltage regulator is defective, does the input and output normally short together when its turned on?

The regulator I'm using is LM2940 with 22uF grounded electrolytic capacitors at its input and output.

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    \$\begingroup\$ My first guess when faced with this problem would be that there is a short circuit between the regulator's input and output. (perhaps not right at the regulator, but somewhere on the board). \$\endgroup\$ Commented Jul 13, 2018 at 23:33
  • \$\begingroup\$ Right, so test for a short with power off. If short found, remove regulator and test for a short again. That will tell you conclusively if the short is through the regulator or intrinsic to your board / wiring \$\endgroup\$
    – vicatcu
    Commented Jul 14, 2018 at 0:09
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    \$\begingroup\$ could just be the ground connection is bad. \$\endgroup\$ Commented Jul 14, 2018 at 5:17

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if that happened it would be defective, but that's not the only possible failure mode.

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It turned out after all that something inside the regulator in question IS defective.

This is because I replaced the "defective" regulator with another one from the same package with the exact same part number and soldered it in place exactly like the last time and the voltage outputs are now correct.

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