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I have a power supply KIKUSUI MODEL PAB 250-0.25A (photo below).

The voltage source used to work correctly, but my roommates have used it for a while and now whenever I connect it to a load and toggle the "output" to ON, it gives at most some 20 millivolts. I connected it only to a 220R resistor and an LED (which is forward-oriented) but for any load it just drops to mV whenever the "output" is on.

Do you have any idea about what is happening, and why the power supply may be behaving this way? Maybe any testing techniques to troubleshoot the problem?

enter image description here

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    \$\begingroup\$ What’s the current limit set to? \$\endgroup\$
    – winny
    Commented Jul 5 at 18:46
  • \$\begingroup\$ @winny the max current allowed for the supply is 0.25A I think. I always put the Current potentiometer on max and just regulate the voltage. But I've tried adjusting the current and the behavior remains the same (but for even less mV). When I put it on C.C and [A] option, the max current it drives is 0.033A. No more than that \$\endgroup\$
    – ludicrous
    Commented Jul 5 at 18:58
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    \$\begingroup\$ Probably broken. Take it apart and measure all rail voltages. If there, probably blown output pass transistor. \$\endgroup\$
    – winny
    Commented Jul 5 at 19:04

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The PAB 250-0.25A has an input and an output fuse. Check the output fuse, it's a normal 1/4" x 1-1/4" type rated at 300mA.

If it is open, replace it with the same type and rating.

enter image description here

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    \$\begingroup\$ It was it! Thank you very much! \$\endgroup\$
    – ludicrous
    Commented Jul 5 at 23:07

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