Adaping a Generic Power Supply for a HP Laptop

The power supply I bought in Kandy for for my HP DM1 laptop stopped working. At the local computer store I tried a couple of replacement HP power-supplies. These made an odd beeping noise and delivered no power. So instead I cut the DC plug off the failed HP unit and soldered a socket on the cable. I then plugged the generic power supply from my old Kogan Agora Laptop into the socket. Even though the two power supplies have slightly different specifications (HP: 18.5 Volt and 3.5 Amp. Kogan: 19 Volt 3.42 Amp) the setup works fine.