NC100 Fuser Service Manual
Contents
1. Light goes straight When an OHP sheet with a full color copy image is projected on a screen the color toner areas on the OHP sheet are visible as black This because the light passing through the OHP is diffused and refracted by the unevenness of the colored toner and the light does not reach the screen However when the OHP sheet is passed through the fuser unit the colored toner on the OHP sheet is made even by pressure and heat After this processing the light from the OHP lamp goes straight through the colored toner to the screen and you see the color image projected on the screen 10 4 1 January 1990 5 OVERVIEW 1 H C G D F The image is fused to the OHP sheet A using a fuser sheet B and rollers which apply heat and pressure The fusing rollers consist of the hot roller C and the pressure roller D Pressure is constantly applied between the rollers However when the upper cover is opened the pressure between them releases This makes it easier to remove misfed paper and to replace the fusing rollers The fusing lamp E which is located in the hot roller is turned on and off to maintain the operating temperature The temperature control circuit monitors the hot roller surface through a thermistor F The cleaning felt G which is located in the upper cover cleans the hot roller The thermoswitch protects the hot roller from overheating The Hot roller strippers H separate the OHP sheet2. 1 January 1990 1 SPECIFICATIONS Maximum Transparency Size Fuser Sheet Size Warm Up Time Fusing Speed Fusing Lamp Power Source Power Consumption Dimensions W X D X H Weight A4 or 8 1 2 X 11 A4 300 X 210 mm 11 9 X 8 3 8 1 2 X 11 284 X 216 mm 11 2 X 8 5 Approximately 60 sec 20 C 43 sec sheet 50 Hz 37 sec sheet 60 Hz Halogen Lamp 950W 115V 60Hz 220V 50Hz 240V 50Hz Stand by 250W Minimum 50W Maximum 1kW 490 X 205 X 125 mm 19 3 X 8 1 X 5 4 inches 8 64 kg 19 1lb 10 1 1 January 1990 2 MECHANICAL COMPONENT LAYOUT 1 Cleaning Felt 2 Hot Roller 3 Pressure Roller 4 Exit Rollers 5 Drive Gears 1 January 1990 3 ELECTRICAL COMPONENT LAYOUT 220V 240V Thermistor TH Transformer T 220V 240V only Thermoswitch TS Circuit Breaker CB Fusing Lamp L Upper Cover Safety Switch SW 2 Drive Motor M Distribution Board PCB 2 Control Board PCB 1 Triac TR Capacitor C Main Switch SW 1 LED Board PCB 3 Resistor R 115V only 10 3 1 January 1990 4 BASIC THEORY OF FUSER UNIT Not processed by the fuser After fuser unit processing Screen Screen Shadow Shadow Color Color Transmitted annn Transmitted sie aig Black Black Black Light Black Projection Light Projection i i Colored Toner f f f OHP Sheet Light diffuses Light from OHP t t 1 Light from OHP
3. d mechanically see DRIVE MECHANISM 10 11 1 January 1990 8 REPLACEMENT AND ADJUSTMENT 8 1 HOT ROLLER REPLACEMENT 1 Open and remove the upper cover A the left cover B and the right cover C 4 screws each 2 Remove the support cover of the hot roller D 2 screws 10 12 1 January 1990 3 Remove the left lamp terminal A 2 screws 4 Pull out the fusing lamp B 10 13 1 January 1990 D c SS E MA AZA cu W 5 Remove the right gear A of the hot roller 1 C ring B 6 Remove the hot roller holder C 2 screws 7 Remove the hot roller D with C ring E and holder NOTE When the hot roller is pulled out make sure the upper cover is opened in order to release the hot roller pressure 8 Remove the C ring from the hot roller 10 14 1 January 1990 8 2 PRESSURE ROLLER REPLACEMENT A wus Ap 1 Perform steps 1 to 9 of HOT ROLLER REPLACEMENT 2 Remove the paper feed guide plate A 1 screw 3 Remove the pressure roller B 2 bushing 10 15 1 January 1990 8 3 THERMOSWITCH REPLACEMENT 1 Perform steps 1 to 9 of HOT ROLLER REPLACEMENT 2 Remove the entrance A and upper B guide plates 2 screws and 2 spac ers 3 Remove the upper stay C 2 screws 4 Remove the thermoswitch D 2 screws 10 16 1 January 1990 8 4 THERMISTOR REPLACEMENT 1 Perform steps 1 to 9 of HOT ROLLER REPLACEMENT 2 Remov
4. e the entrance A and upper B guide plates 2 screws and 2 spac ers 3 Remove the upper stay C 2 screws 4 Remove the thermistor D 3 clamps and 1 connector 10 17 1 January 1990 8 5 FUSING PRESSURE ADJUSTMENT 1 Open the upper cover A 2 Remove the paper feed guide plate B 1 screw 3 Remove the rear cover C 2 screws 4 Loosen the nuts D of the adjusting screws E 5 Adjust the fusing pressure by loosing and tightening the adjusting screws as follows FUSING PRESSURE DIRECTION OF THE ADJUSTING SCREW Weaker Counterclockwise Stronger Clockwise NOTE After adjustment make sure that unfused copies and paper creasing do not occur 6 Tighten the nuts of the adjusting screws 10 18
5. from the hot roller and direct it to the exit rollers I The fuser sheet has two functions it prevents toner from sticking to the fusing rollers and it prevents paper misfeeds 10 5 1 January 1990 6 MECHANICAL OPERATION 6 1 DRIVE MECHANISM An ac motor A drives the fusing rollers and the exit rollers when the drive motor turns on drive power is transmitted to each part as follows Drive Motor Idle Gear B gt Release Gear C Transmission Gear D Pressure Roller Gear E gt Hot Roller Gear F ea Idle Gears G Exit Roller Gear H When the upper cover is open the release spring I lifts the release arm J and uncouples the release gear from the transmission gear This provides mechanical safety protection When the upper cover is closed the projection K of the upper cover pushes down the release lever L This force is transmitted to the release gear through the release arm The release gear then contacts the transmission gear and the main motor s drive power is transmitted to the rollers 10 6 1 January 1990 Close the upper cover Open the upper cover qu f 10 7 1 January 1990 6 2 PRESSURE RELEASE MECHANISM A C gt Open the upper cover Close the upper cover To make it easier to remove misfed paper and to replace the fusing rollers the fusing pressure is released when the upper cover is opened When the upper cover is opened the pivot A of t
6. he upper cover moves to the rear side and the pressure roller brackets B are pushed down The pressure roller C which is mounted on the pressure roller brackets also moves down and separates from the hot roller D When the upper cover is closed the pivot of the upper cover moves to the front side and the pressure roller brackets are raised by the force of the pressure springs E The pressure roller moves up and contacts the hot roller This fusing pressure can be adjusted by tightening and loosening the screws F mounted on the pressure springs One on each end 10 8 1 January 1990 7 ELECTRICAL OPERATION 7 1 FUSING LAMP CONTROL Circuit Cover Main Breaker SW SW 220V 240V Pa Distribution Board DC Power Supply Circuit Zero Cross Circuit Trigger Circuit Display Circuit Thermistor LED Board The ac power from the outlet A goes directly to the fusing lamp The fusing lamp is controlled by the triac the distribution board and the control board Control Board The dc power supply circuit on the distribution board steps down the wall outlet voltage to 15 volts In the 220V 240V version the ac power from the outlet is stepped down to 100 volts ac by an outer transformer and then goes to the dc power supply circuit 15 volts dc is supplied to all dc circuits The zero cross circuit on the distribution board produces and sends a
7. zero cross signal B to the lamp trigger circuit The temperature control circuit on the control board detects the fusing temperature by monitoring the resistance of the thermistor and sends the control signal to the lamp trigger circuit The lamp trigger circuit sends the fusing lamp trigger signal C which has the same timing as the zero cross signal to the triac to turn on the triac The fusing lamp then receives full power D from the wall outlet 10 9 1 January 1990 Based on the value of the thermistor s resistance the triac turns on and off to keep the hot roller s temperature in the operation range 155 C 5 C The lamp trigger circuit sends the trigger signal until the temperature reaches the operating level At the same time the control signal goes from the temperature control circuit to the display circuit The display circuit controls the LED display During stand by the LED blinks to display the waiting time When the temperature reaches to the operating level the LED is lit to show that the fuser is ready to use 10 10 1 January 1990 7 2 DRIVE MOTOR CONTROL Circuit Cover Main Drive Breaker SW SW Motor Capacitor The ac power from the wall outlet goes directly to the motor When the main switch is turned on the motor starts rotating However when the upper cover is opened the drive motor stops rotating For safety purposes the drive motor is stopped both electrically by the cover switch an
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