HP Laserjet 4 Manual
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Jam Location Checks and Action Required Input Area Jams (Sensed by PS1.)1. Check that the Transfer Roller is fully seated and shows no sign of wear. 2. Check that the Toner Cartridge is fully seated. 3. Check that the cassettes are not overfull and the media is loaded correctly. 4. Ensure that the media meets specs. (media is not too smooth or rough), and it has been stored properly. 5. Ensure that the paper tray is fully seated (especially if printing from the Lower Cassette). 6. Ensure that the spring force of the Lower Cassette is set correctly. Registration Area Jams (Sensed by PS1.)1. If paper is damaged at the Registration Sensor (PS1), check that the Transfer Charge Roller is properly seated. Lower Cassette Paper Jams (Sensed by PS1.)1. The LC Tray (Tray 3) is not fully seated into the printer. Seat the LC Tray firmly into the printer. 2. The Lower Cassette feed pressure (spring force) adjustment is incorrect. Set the spring force as shown in Chapter 3. Fuser Assembly Jams (Sensed by PS3.)1. Check that the Fuser Pressure Roller Levers are down (LJ4 and 4 Plus Only). 2. Check that the Exit Sensor Arm (PS3) is free throughout its travel and that the Exit Sensor Arm is installed correctly. False Paper Jams Paper Jam occurs when the last sheet of paper is fed from the tray.1. PS1, PS3, or PS5 are damaged or mechanically broken. 2. The sensor wires are damaged or disconnected. 3. 4.The rear door is open. Paper out sensors in the paper tray or envelope feeder may be defective, or the sensor flags may be broken or missing. PS2 is the sensor for the PC Tray (Tray 2), PS4 is the sensor for the MP Tray (Tray 1), PS6 is the sensor for the LC Tray (Tray 3), and PS7 is the sensor for the Envelope Feeder. Table 7-7Paper Jam Troubleshooting Checklist Troubleshooting 7-21
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PS1 (Input/Registration Sensor) Check 1Power ON the printer with the top cover open. Wait for the 12 PRINTER OPEN (or CLOSE PRINTER COVER) message. 2Engage PS1 by taping it down. aFor the LaserJet 5, install the toner cartridge. 3Close the top cover. The 02 WARMING UP message should display. 4After the fuser warms up, the main motor should turn on. 5The 13 PAPER JAM message appears if the sensor is working correctly. 6If the 13 PAPER JAM message does not appear, check that PS1 was fully engaged, then replace PS1. 7Remove the tape from PS1, install the Toner Cartridge and close the top cover. 8The display should change from 02 WARMING UP to 00 READY. If the 13 PAPER JAM message persists, replace PS1. Figure 7-4 PS1 Input/Registration Sensor 7-22 Troubleshooting
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PS3 (Exit Sensor) Check 1Open the rear door (cover) of the printer. 2The display should read 13 PAPER JAM (or REMOVE PAPER JAM) immediately after the door is opened. 3Close the rear cover. The display should change from 02 WARMING UP to 00 READY. aIf the 00 READY message does not appear, check that the rear door is not damaged, and the the door closes and latches properly. bIf the PAPER JAM message does not appear, replace PS3. Pickup Motor Functional Test (M2) There is not a good method with which to access the test points around the Pickup Motor (M2) circuit. Therefore, when troubleshooting Pickup Motor failures, perform the following in the order listed (see Figures 7-11 and 7-12 for component location). 1Reseat J601 and J602 on the Paper Control PCA. 2Reseat J201 on the DC Controller. Reseat J703 on the Sensor PCA. 3Verify that the Paper Control PCA and the Sensor PCA are firmly seated into one another. 4Replace the Pickup Motor. 5Replace the Paper Control PCA. 6Replace the Sensor PCA. Troubleshooting 7-23
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Lower Cassette Functional Check When troubleshooting a Lower Cassette failure, always prove the failure by removing the Lower Cassette from the printer. Next, test the printer’s ability to move and print media satisfactorily without the Lower Cassette installed. The Lower Cassette is a field-serviceable item. The procedures for removing and replacing the Lower Cassette components are in Chapter 6. Replacement parts for the Lower Cassette Assembly are listed in Chapter 8. After the failure has been associated with the Lower Cassette Assembly, perform the following in the order given. Test the repair after each replacement. 1Reseat all connectors in Lower Cassette. 2Replace the Lower Cassette Pickup Motor. 3Replace the Paper Control PCA. 4Replace the DC Controller. 7-24 Troubleshooting
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14 NO EP CART Message The printer detects the presence of the Toner Cartridge and the level of toner present in the cartridge through the condition of the ANTIN signal. The ANTIN signal becomes part of the serial data stream used to communicate with the DC Controller (see Figure 7-5 for cartridge components). Troubleshoot the 14 NO EP CART (or INSTALL TONER CARTRIDGE) message as follows: 1Reseat the Toner Cartridge. Try a new or known good Toner Cartridge. 2Check the High Voltage Contacts for damage. If the contacts are dirty or damaged, clean the contacts after the repair. 3Replace the High Voltage Power Supply. 4Check and reseat the HVPS cable. 5Replace the DC Controller. 16 Toner Low Message The TONER LOW message results as the level of toner in the cartridge cavity falls past the minimum level. The level is sensed by a mechanism similar to an antenna, which detects the AC Developer Bias Voltage applied to the developer mixture. If the TONER LOW message cannot be cleared by shaking or replacing the Toner Cartridge, perform the steps listed for troubleshooting the 14 NO EP CART message. Troubleshooting 7-25
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1 245 6 3 Figure 7-5 Toner Cartridge Components Callout Assembly 1 Toner Low Voltage Contact 2 Developer Roller High Voltage Contact 3 Developer Roller 4 Photoconductive Drum 5 Charge Roller High Voltage Contact 6 Charge Roller Table 7-8 Toner Cartridge Components 7-26 Troubleshooting
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41.X ERROR Message A 41.X ERROR (misprint) indicates that a temporary malfunction has occurred with the print engine (NOT a Formatter error). Occasional occurrences of this message can be expected. However, persistent 41 ERROR messages indicate a problem requiring attention. The 41.X ERROR is usually accompanied by a blank, or partially printed page. Pressing the [Continue] (or Go) key re-prints the page, and continues the print job. A 41 ERROR occurs due to the following conditions: •Incorrect Universal Tray Switch setting. Set the Universal Tray and the Lower Cassette Tray paper size as shown in Chapter 3. •Wrong size paper in tray. Check that the Universal Tray, and/or the Lower Cassette settings match the installed paper. •An unstable or temporary loss of the Beam Detect pulse. This problem normally is accompanied by a partially printed page, often with thin horizontal black lines, deformed characters, or solid black areas. Loss of the Beam Detect pulse for more than 2 seconds results in a 51 ERROR condition. •Paper reaching the Input Paper Sensor (PS1) before it is expected. This is accompanied by a blank page. This normally is due to paper feed problems. Proceed as directed in the following table. Troubleshooting 7-27
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Error Message Recommended Action 41.1 ERROR Noisy Vertical Sync (VS)Reseat all connectors on the DC Controller, the Laser Drive PCA, the Scanner Connector and the Beam Detect Connector. 41.2 ERROR Beam Detect (BD) weak or unstable.Reseat all connectors on the DC Controller. Also check the Laser Scanning Assembly connections. 41.3 ERROR Paper Multifeed1. Incorrect size selection on the cassette. 2. One of the cassettes is overfull. Remove the extra paper from the overfull cassette. 3. Check the paper for edge damage. Improperly cut edges can lock together causing multi-feeds. 4. 5. Check that the pickup rollers and separation pad are not worn. Replace the rollers and pad as a set if necessary. Ensure that the corners of the paper are tucked in the tray’s retainers. Check the paper tension adjustment on the optional Lower Cassette, if attached. Refer to procedure in Chapter 3. 41.4 ERROR Vertical Sync Late (VS) SignalReseat the DC Controller and Formatter PCA Connections. 41.5 ERROR Undetermined CauseReseat the DC Controller and Formatter PCA connections. See Figures 7-11 through 7-17 for connector locations. Table 7-9 41.X ERROR Checks 7-28 Troubleshooting
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50 SERVICE Error - Fuser Malfunction WarningThe Fuser Assembly is HOT. Allow the assembly time to cool before servicing. The purpose of the fusing system is to maintain a constant temperature on the fuser roller. A high intensity fusing lamp, located inside the fuser roller, provides the high temperature required for the fusing process. While the printer is in standby mode, a temperature of approximately 172° C is maintained on the fuser roller. While the printer is in printing mode, a temperature of around 183° C is maintained. The main components of the Fuser Assembly are the fusing lamp and its associated fusing and pressure rollers, a thermistor, thermoprotector, and the AC controller/safety circuitry in the AC Power Supply. The fusing lamp is a specially designed 460 watt (220V), or 500 watt (115V) halogen lamp that operates at line voltage. The thermistor is a resistor whose value changes with temperature. At room temperature the resistance value of the thermistor should be between 180k ohms and 280k ohms.The thermoprotector is a switch designed for over-temperature protection, and opens when the temperature reaches 230° C. The thermoprotector will not reset when the fuser cools. It may be necessary to replace the thermoprotector or fuser assembly if the thermoprotector opens. The following conditions result in a fusing error: 1Unable to maintain a temperature above approximately 180° C. 2A temperature above 230° C. 3A condition wherein a temperature of 165° C is NOT reached within 90 seconds after power-up. Note If a 50 SERVICE error message is displayed, turn the printer OFF for at least 10 minutes. Failure to wait the full 10 minutes before turning the printer ON results in a continuation of the error message and the shutting off of the fuser lamp current during this time, though the source of the error may have already been resolved. Troubleshooting 7-29
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NoteThe 50 SERVICE error message can be cleared immediately by shorting the C202 leads on the HP LaserJet 4/4M (or the C205 leads on the HP LaserJet 4 Plus/4M Plus/5/5M/5N) on the DC Controller. Remove the Formatter PCA to access the DC Controller as shown in Chapter 6. Checks Action Is the Fuser Assembly correctly seated?Reseat the Fuser Assembly. Allow adequate time for the error message to clear (10 minutes) and turn the printer ON. Is the Fuser Bulb/ Thermoswitch open? 1. 2.The fuser bulb and thermoswitch are wired in series. To check if one or the other is defective, perform the following: Remove the Fuser Assembly from the printer. Use an ohmmeter and measure the continuity between pins (see Figure 7-6, callout 1). It should read about 2 ohms (about 4 ohms for the 220 volt fuser). If an open condition is detected, either the fusing bulb or the thermoswitch is defective. Replace the defective component (refer to Chapter 6) or replace the complete Fuser Assembly. Is the Thermistor defective? 1. 2.Remove the Fuser Assembly and let it cool to room temperature. Use an ohmmeter and measure the resistance between pins (see Figure 7-6, callout 2) It should read about 220 K ohms +/- 40 K ohms at ambient room temperature. If the thermistor is either open or shorted, replace the thermistor (refer to Chapter 6) or the complete Fuser Assembly. Does the error persist? 1. 2.Verify all cabling is correct. Replace the following components in the order given: Power Supply Assembly DC Controller PCA See Figure 7-11 for Fuser Assembly location and Chapter 6 for removal and replacement, as necessary. Table 7-10 50 SERVICE Fuser Malfunction Checks 7-30 Troubleshooting