Klein 3000 Series Troubleshooting Manual page 75

SYSTEM 3000 OPERATIONS AND MAINTENANCE MANUAL
the probable cause is the failure of the backup battery on the CPU board.
Locate the battery on the CPU board. It is near the heatsink and is labeled U14.
The battery is piggybacked on top of the IC. Note the location of the pin one dot.
L-3 Klein Associates, Inc. TROUBLESHOOTING GUIDE 4-71