4-94 Service ManualWarning: When replacing any of the following components:• Scanner interface card assembly• System card assembly• Scanner unit assemblyOnly replace one component at a time. replace the required component and perform a POR before replacing asecond component listed above. If this procedure is not followed, the printer will be rendered inoperable. Neverreplace two or more of the components listed above without a POR after installing each one or the printer willbe rendered inoperable.These components can be used as a method of troubleshooting as long as the machine is booted into diagnosticmode or is operating in diagnostic mode. Once a component has been installed in a machine and powered upinto user mode, it cannot be used in another machine. It must be returned to the manufacturer.2. Remove the scanner controller card cage cover.3. Remove all cables.4. Remove the two plastic screws (A) and screw (B) securing the ground strap to the left side of the scannerunit assembly.6. Remove the two plastic screws (C) securing the right side of the scanner unit assembly to the printer.BAScanner unit assembly removal (models X651, X652/5535dn, X654, and X656)and X656)” on page 4-85.1. Remove the ADF unit assembly. See “ADF unit assembly removal (models X651, X652/5535dn, X654,and X656)” on page 4-136.5. Remove the scanner cover, right. See “Scanner cover, right removal (models X651, X652/5535dn, X654,
