Canon LBP-2000 Service Manual download pdf (Page 55)

CHAPTER 2

2 - 16

4 . Protective functions

The printer is equipped with the following protective functions to prevent malfunction of the fixing

heater:

a. Thermistor (detecting overheating)

The ASIC and the high-temperature detection circuit found on the DC controller PCB monitors the

voltage readings of the main thermistor and the sub thermistor; if the main thermistor detects a

voltage level which is equivalent of the following temperature, the CPU will identify the condition

as being overheating:

• 220°C or higher (by main thermistor TH101)

b. Thermistor (detecting connector disconnection)

The connector disconnection detection circuit found on the DC controller PCB monitors the THCNCT

signal; if the THCNCT signal goes Low, the CPU will identify the condition as indicating disconnec-

tion of the thermistor connector.

c . Thermistor (cutting the power for overheating)

If the internal temperature of the thermal switch (THSW101) exceeds about 230°C, thermal switch

will go OFF, thereby cutting the power to the fixing heater.

d. Detecting the activation of the fixing heater

The fixing heater activation detection circuit found on the power supply PCB assumes that the /

HEATDT signal is Low if the /FSRDRV signal is Low (fixing heater ON). If /HEATDT goes High

while /FSRDRV signal is Low (fixing heater ON), the ASIC will identify the condition to be an error

in the activation of the fixing heater (triac short circuit).

Download Service Manual And Resetter Printer at http://printer1.blogspot.com

1 2 ... 50 51 52 53 54 55 56 57 58 59 60 ... 221 222

No comments

Canon LBP-2000 Service Manual Page 55