Guest

Cisco MWR 1900 Mobile Wireless Routers

Field Notice: FN - 62812 - MWR1941-DC Fan Failures - Replace Unit


Revised May 13, 2009

June 5, 2007


NOTICE:

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE FIELD NOTICE OR MATERIALS LINKED FROM THE FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.

Products Affected

Products Affected
MWR-1941-DC
MWR-1941-DC-2E1
MWR-1941-DC-2T1

Serial Numbers

Sequential #
From xxx0628yyyy to xxx0900yyyy

Problem Description

The content of this field notice is specific to the fans designed for use in the MWR-1941-DC router. No other platforms are covered by this field notice.

The MWR-1941 router fans could contain a defect causing one or more of the system fans to stop spinning or slow to the point prematurely where the system reports a fan failure.

The router should perform as configured providing it has not exceeded the maximum operating temperature. However, system fan failures will reduce the overall airflow and cooling within the box and can result in higher overall operating temperatures. If the router's internal temperature rises above the maximum operating range, service (network connectivity or application usage) may be impacted depending on environmental conditions. Sustained use of the router beyond the maximum operating temperature could result in permanent damage to the internal components.

Background

This issue has been linked to a specific fan vendor manufacturing problem. The root cause was identified and appropriate steps taken to resolve the problem. All MWR-1941-DC units manufactured after January 1, 2005 do not appear to have fans installed that exhibit this issue.

Problem Symptoms

The MWR-1941 router fans could contain a defect causing one or more of the system fans to stop spinning or slow to the point prematurely where the system reports a fan failure. The problem was linked to a manufacturing issue. During use, the lack of sufficient lubrication could cause the fan blades to stop spinning or slow to the point where the system reports a failure.

Router# show log

Feb 1 15:42:41.892 UTC: %FAN-3-FAN_FAILED: Fans had a rotation error reported.
Feb 1 15:47:41.903 UTC: %FAN-3-FAN_FAILED: Fans had a rotation error reported.
Feb 1 15:52:41.913 UTC: %FAN-3-FAN_FAILED: Fans had a rotation error reported.
Feb 1 15:57:41.923 UTC: %FAN-3-FAN_FAILED: Fans had a rotation error reported.

Router# show environment all


Fan status:

Warning - low fan rpm condition detected.

Overtemp Alarm status:

normal.

Workaround/Solution

Workaround:

None

Solution:

Cisco recommends all customers with a MWR-1941-DC that shows a temperature alarm or a failed fan, in the affected Serial Number range (refer to the section titled Affected Serial Numbers) replace the affected hardware.

As of approximately May 22, 2007, new products that were manufactured under Engineering Change Order (ECO) E085259 are designed to ensure more reliable fan operation. Refer to How to Identify Hardware Levels below for instructions on how to view the version and deviation of in-service product.

Product shipped from Service Logistics may still exhibit this problem. To ensure an RMA replacement is not affected by this problem, use the Upgrade Form below.

Note: Replacements fulfilled through this process typically take three business days or more to arrive on-site, therefore service level agreements do not apply to replacements obtained using the upgrade form.

How To Identify Hardware Levels

The image below shows the serial number location on the back of MWR-1941 router.

To determine the chassis serial number using IOS CLI, review the output from the show diag or show inventory command. The output below displays an example.

Router#show diagnostic

mwr1900 Backplane EEPROM :
PCB Serial Number : JAE07460097
Processor type : 67
Top Assy. Part Number : 800-22440-01
Board Revision : A0
Fab Part Number : 28-4226-06
Deviation Number : 0-0
Manufacturing Test Data : FF FF FF FF FF FF FF FF
RMA Number : 255-255-255-255
RMA Test History : FF
RMA History : FF
Chassis Serial Number : JMX0751L427
Chassis MAC Address :
MAC Address block size : 48
Field Diagnostics Data : FF FF FF FF FF FF FF FF

A chassis that has a Top Assembly Part Number that ends in -05, regardless of the serial number range, is not affected by this issue.

The Chassis Top Assembly Part Number sticker can be found on the back of the chassis next to the serial number sticker. The show diagnostic command also shows the Top Assembly Part number.

The Top Assembly Part Number looks like 800-xxxxx-05, where xxxxx is a series of numbers.

Affected Serial Numbers

The serial number range affected by this issue starts at xxx0628yyyy and ends at xxx0900yyyy. If your serial number falls between 0628 and 0900, the product could be affected by this issue.

The three letters "xxx" of the serial number range above correspond to any lettering in that character space. The "yyyy" correspond to any number in that character space of the serial number.

For example -

A serial number JMX06514567 could be affected by this field notice since the middle date codes that are in bold fall within the affected manufacturing date range.

xxx = JMX
0651 = falls between 0628 and 0900
yyyy = 4567

A serial number JMX04141234 would not be affected by this field notice as the date codes that are in bold do not fall within the affected manufacturing date range.

xxx = JMX
0414 = does not fall within 0628 and 0900
yyyy = 1234

Note-

A chassis that has a Top Assembly Part Number that ends in -05, regardless of the router serial number, is not affected by this issue.

The Chassis Top Assembly Part Number sticker can be found on the back of the chassis next to the serial number sticker. The show diagnostic command also shows the Top Assembly Part number.

The Top Assembly Part Number looks like 800-xxxxx-05, where xxxxx is a series of numbers.

Field Repair Strategy

Customers who fill out the upgrade form will receive an MWR-1941-DC that contains improved fan dependability.

The MWR-1941-DC that is sent from Cisco is the chassis - it does not come with cards. Customers are responsible for removing their interface cards and compact flash from their existing chassis and installing them in the new chassis.

To prevent damage to the Cisco MWR-1941-DC by random electrostatic discharge (ESD), the use of wrist straps is highly recommended.

Please review and follow the safety recommendations found in the online guide for Preparing to Install the Cisco MWR-1941-DC Router.

Revision History

Revision Date Comment
1.1
13-MAY-2009
Removed Umpire Program
1.0
05-JUN-2007
Initial Public Release

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:

Receive Email Notification For New Field Notices

Product Alert Tool - Set up a profile to receive email updates about reliability, safety, network security, and end-of-sale issues for the Cisco products you specify.