HP LaserJet 4 Service Manual - Page 254

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. 1 Reseat all connectors in Lower Cassette. 2 Replace the Lower Cassette Pickup Motor. 3 Replace the Paper Control PCA. 4 Replace the DC Controller. 7-24 Troubleshooting