Tenma power supply fails to power up in constant voltage mode

Question

My company recently purchased 8 of these supplies and one will not power up with the CV LED on. When I hold the voltage knob for 3 seconds the CV LED comes on and current indicates 0 and is fine until the supply is restarted.

It is model 72-272072-2720.

jw0752 · Answer

Hi Nicholas, I am interested in your problem but you have not given enough information to actually make a guess as to what is going on. As I understand it the unit will not work when powered on but there is something that you can do to make it work until the unit is cycled to the off position and then back on. Perhaps you can post some pictures and a more detailed description of the procedures needed to make it work or even a video of the procedure. John

nick.s · Answer

Thanks for your replies. I have attached two photos, one showing four supplies just powered on, the one on the left is the “problem” supply, the other picture focuses on the “bad” supply. We have a total of 8 supplies and all but one power up with the CV LED on. It’s easy to get the supply to turn on the CV LED, you press and hold the voltage knob for 3 seconds, you feel and hear a relay and click and then, the supply functions like the rest. The supply with the issue was the first one we used to setup our experiment and we were unfamiliar on all the functions. I think we may have enabled some kind of undocumented mode. Nick

Tenma power supply fails to power up in constant voltage mode

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