
5. TROUBLESHOOTING
B–63465EN/01
100
An ECC error occurred in the SRAM that contains data such as
parameters.
This error occurs when the battery mounted on the faceplate of the base
PC board becomes weak or when data stored in the SRAM is destroyed
by an external cause. Alternatively, this error may be due to a failure in
the memory module or base PC board.
The ECC check method is a method of checking data stored in the SRAM.
This method is employed in place of the conventional parity check.
With the ECC check method, 8–bit correction data is provided for 16–bit
data. If a data error occurs in any bit of the 16 bits, the error is
automatically corrected by the correction data, and the Digital Servo
Adapter operation can be continued. This alarm is issued when a data
error occurs in more than one bit.
With the conventional parity check method, even a single–bit data error
resulted in a system alarm.
The battery is rated at 3 V. If the battery becomes weak, causing a voltage
drop to TYP 2.5 V (2.3 V to 2.7 V), a battery alarm is issued, and “BAL”
is displayed on the alarm screen.
If a battery alarm is issued, replace the battery with a new one as soon as
possible.
Perform memory all–clear operation to start the Digital Servo Adapter.
Alternatively, when there is already a backup copy of SRAM data, restore
the data. Use the boot system for SRAM data backup and restoration.
If the alarm still exists after memory all–clear operation or backup data
restoration, replace the memory module.
After replacing the memory module, perform memory all–clear operation
to start the Digital Servo Adapter. In this case, all data must be set again.
When there is backup data, restore the data then start the Digital Servo
Adapter.
If the alarm still exists even after the above action is taken, replace the base
PC board.
5.11
ALARM 935
(SRAM ECC ERROR)
Causes and Remedies
D ECC check
D Battery check
D Attempting memory
all–clear operation
D Replacing the SRAM
module
D Replacing the base PC
board