What was going on here? Purchased a 12v 10A power supply adaptor to replace one that had failed. Required for a 12v desiccant dehumidifier drawing 5A. The unbranded Chinese adaptor (intake of breath!) would cut out after an hour or so - very hot. Replacement just the same. Extra ventilation did not help. Oddly, introducing an analogue multimeter set to measure amps solved the issue. Got to thinking why. Realised that meter had some simple electronics that might be dealing with currents. I had a spare Drok voltage/current boost module to hand so tried introducing this - sure enough no overheating and no cutting out. So I have amateur knowledge of electronics but am used to problems as of engineering background Curious to know what do the knowledgeable people think is the design issue with the adaptor that causes the problem? Did cost cutting or poor design play a part? Why did introducing more circuitry cure the problem?