For a given load (in this case, your KVM switch, but could be most* anything), the power supply cannot fix both voltage and current. If it fixes the voltage, the current supplied is determined by the voltage an the load. If it fixes the current, the voltage is determined by the current and the load.
On wall wart and similar power adapters, the V rating is the voltage that the adapter supplies. The mA rating is the maximum current the adapter can supply. If your load requires more current at the supplied voltage than the adapter can provide, then the voltage will drop, possibly causing damage to the adapter or the load. So as long as the adapter has the same voltage rating, and at least as high a current rating as the original, you should be just fine. Assuming, of course, that the polarity of the connectors is the same between the two. I suspect your problem may have been that the polarity of the connector on your adapter was opposite that of the original, and the KVM switch didn't have the circuitry to handle inverted voltage.
*OK, there are some pathological cases, but they're few and far between. Your normal device that uses a wall wart for power should behave this way |
