When searching for an alternate power supply my Uncle found an old Bose PS that was 12VDC, we plugged it in and I caught the smell right away and unplugged the PS. Turns out it was Tip Negative... what an oddball power supply!
At any rate, I was surprised the HM powered up just fine when proper power was supplied, I was sure it was gonna be toast after I smelled it cooking, but it lived through that punishment just fine... So you're probably OK. Like Bryan said, if your blower is blowing you should be fine....