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, and both exhibit the same defect. They have never been used and have been stored in their packaging for about a year.
Does anyone have an idea what might be causing this behavior, and how it could be resolved?
AI: Could you provide the exact brand and model number of the UPS units?
It is a no-name UPS. Just bought on AliExpress.
AI: When testing, what are you using as the input power source and what (if anything) is connected to the UPS output? Also, have you checked the battery condition or voltage?
Input was from a USB charger. The batteries' condition was good, but without them it exhibits the same behavior as described. It behaves the same with a small load and without any.
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, and both exhibit the same defect. They have never been used and have been stored in their packaging for about a year.
Does anyone have an idea what might be causing this behavior, and how it could be resolved?
AI: Could you provide the exact brand and model number of the UPS units?
It is a no-name UPS. Just bought on AliExpress.
AI: When testing, what are you using as the input power source and what (if anything) is connected to the UPS output? Also, have you checked the battery condition or voltage?
Input was from a USB charger. The batteries' condition was good, but without them it exhibits the same behavior as described. It behaves the same with a small load and without any.
