Canon LBP-2000 Service Manual page 68

When the power switch is turned on or when sleep state is ended, the fan ON signal (FANON) goes
High and the fan full-speed rotation signal (FANFULL) goes High; the Printer supplies the fan drive
voltage (FANDRV; about 24 V) to rotate the heat discharging fan at full speed. The Printer also
rotates the heat discharging fan at full speed for 30 sec after the end of last rotation (LSTR) and
between sheets.
While printing takes place or while in standby, the Printer causes the fan full-speed rotation
signal (FANFULL) to go Low, and supplies the fan drive voltage (FANDRV; about 16 V) to rotate the
discharging fan at half speed.
The CPU monitors the fan lock detection signal (/FANLOCK) at all times while the heat dis-
charging fan is rotating; if the /FANLOCK signal is Low for a specific period of time or longer, the
CPU will identify the condition as indicating a fault in the heat discharging fan, and will commu-
nicate the fact to the video controller and indicate 'E805' on the LCD in the control panel.
Signal
Fan ON signal (FNAON)
Fan full-speed rotation signal
(FANFULL)
Table 2-2-5
Stop Half-speed rotation Full-speed rotation
0 1
0 0
CHAPTER 2
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