high pitched noise from mh

[MarcusSmith]

I have a 150w hqi pendant that is making a noise now that I didnt notice before, I had just installed a new bulb yesterday, a phoenix. I disconnected the light and reconnected it and the noise was gone but after a couple minutes the noise has come back.
Does anyone know what causes this and how to stop it?
thanks

 

[stevereef]

Sometimes this may be due to the connection. When the lights are on the off cycle, I'd try taking the bulb out, give it a good cleaning with a dry soft cloth before carefully seating it back into the socket. Be sure the bulb is seated properly and the connection is aligned well. Then wait until the light turns on and see if you still have the same problem. If you do, contact the manufacture and see if they can help troubleshoot. I hope this helps.