I have a small Chinese-made UPS. Currently, I am using the version with a 12 V output, but it is behaving oddly: it typically outputs only about 3.4 V. However, if I press on the chip XR2981 in the center of the board (labeled “U4” on the picture), it temporarily outputs the correct 12 V.
I have already tried resoldering the contacts, but the issue persists.
Interestingly, I own two identical UPS units,...
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