Strange noise

[RDV8]

Hi all
Friend of mine just bought a 1999 450 Chimaera with only 17k on the clock. It's sitting in my garage whilst he sorts out his own storage.
This afternoon I was looking over the engine bay and could hear a strange humming or electrical buzz...best way to describe it...definitely coming from the alternator. Not very loud but consistent.
Ignition is off
Alarm not activated
Alternator is brand new and is cold to the touch.
Any suggestions please as the last thing we want is a fire....especially as it's parked next to mine !
Many thanks
R

[chris52]

Disconnect the battery just in case. I doubt it's anything to worry about but safety first.
Chris

[RDV8]

Will do but need to know what 's causing the noise if it comes back.
Cheers R

[chris52]

Disconnect the cables from the back of the alternator if the noise disappears then it will more than likely be a defective rectifier/voltage regulator I have heard of them buzzing before if faulty.

[RDV8]

Will try tomorrow......welcome any other opinions also.
Ta
R

[RDV8]

Thanks Chris........alternator will be exchanged....faulty unit.