CANON MP C555
Service Manual

MultiPASS C530/C560 Chapter 1: General Description

5.4.2 Data in the control processing memory (SRAM)
SRAM is backed up by a lithium battery. It can retain the stored data for 5 years after the power is turned off. SRAM stores the following data: All the data the user entered with the menu system, the activity reports and other report-generating data, the redial data containing the redial destinations set with the Redial key, the servicing data set by repair personnel with the service soft switch, and the CS LED lightson duration data. SRAM stores almost all of the data which can be entered or set. These stored data can be checked with various reports. Jumper Plug Precautions The data in the SRAM mounted on the SPCNT Board is retained by means of a lithium battery. However, it is important to keep in mind that, for the SPCNT Board supplied as a service part, the jumper plug (JP3) is not shorted so that power is not drawn, thereby preventing unnecessary consumption of power during storage. When mounting the SPCNT Board, be sure to remove the shorting plug from one of the two shorting pins, and then put it so as to span the two shorting pins. Further, for the SPCNT Board that comes originally with the machine, a chip jumper (R90; on the back of the board) is used for shorting instead of a shorting plug; and power is always flowing from the lithium battery of any SPCNT Board that came with the machine. If you want to stop the power for PCB repairs, remove the R90 chip jumper before starting the work; after the work, be sure to solder the chip jumper back in place, and check the voltage of the battery to make sure that it has not been exhausted. If the battery has reached the end of its life, replace it with a new one.

NOTE

Jumper plug (JP3)

Figure 1-26 Attaching the Jumper Plug
Lithium battery life The lithium battery can last for over 5 years after the power is turned off. When the power is on, the lithium battery�s power is untapped. Therefore, the actual battery life can be much longer. When the lithium battery becomes exhausted, �DATA ERROR� will be displayed after the power is turned off or on. When this happens, replace the lithium battery. Since the data in SRAM will be lost when the battery is replaced, it cannot be printed out. After the lithium battery is replaced and the power is turned on, �DATA ERROR� will be displayed. Press the Set button to discard the contents in SRAM and initialize it to the factory defaults. Refer to Chapter 3: 3.1 CS LED lights-on Duration Adjustment on Page 3-6 to reset the CS LED lights-on duration.

NOTE

1-55