I have bought this electronic drumkit by Roland about a year ago. It was second hand. It came with a 230v ac to 9 v dc 1000ma adapter. On the drum module, a few types of compatible adapters are written. It's official. The adapter I have is one of them and it's also made by Roland. Now the problem. I wanted to take a look at how many amps the drum module takes from the maximum of 1A of the adapter by screwing the module open and using my multimeter on the power dc input. Weirdly, it shows that it's using about 4.3 amps, which is way more than the adapter should be able to handle. Then, I unplugged the module and left the adapter plugged into my outlet and checked the output voltage. It shows 13.4, not 9. This really surprised me. I checked my multimeter by checking other power supplies for their voltages, and they show about the same as they are claiming to output.
Does anyone know what this could be?