Revised April 25, 2008
November 7, 2003
THIS FIELD NOTICE HAS BEEN EXPIRED AND IS NO LONGER MAINTAINED OR UPDATED BY CISCO.
THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE, WARRANTY OR SUPPORT. USE OF THE INFORMATION ON THIS FIELD NOTICE OR MATERIALS LINKED FROM THIS FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.
The power supply used in the Cisco10720-DC system may emit a high pitched humming sound under normal operations.
It has been found that a certain capacitor used in the DC power supply can cause the supply to emit a high pitched sound under some situations. This sound is different than what may normally be heard from a power supply, and the intensity of the sound is based on the load of the power supply. Under a no load condition, the sound in the high frequency range has the highest audible noise. This issue occurs only with capacitors provided by one vendor and not all units emit sound at the same level. In all cases, the sound is still well within the allowed specifications of noise radiation for the system. Also, the reliability of the power supply is not reduced in those supplies which emit this sound. Manufacturing has discontinued use of capacitiors from this vendor.
Except for the different sound from the power supply, there are no other symptoms for this issue.
This field notice is for information purposes only and no workaround is required for this issue. Approximately 300-400 units were built which may emit the high pitched humming sound, but all of these units will operate normally with no degradation of performance. A return materials authorization (RMA) is not required for a unit with this issue.
For More Information
If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods: