MODEL 8559A

SERVICE

SECTION Vlll

SERVICE

8-1.INTRODUCTION

8-2. This section provides instructions for troubleshooting and repairing the HP Model 855914 Spectrum Analyzer. It includes circuit descriptions, general servicing hints and information, arts identification iilustrations and lists, block diag;ams, component locations diagrams, and schematics.

To troubleshoot and repair this instru- ment, it must be removed from the display mainframe and reconnected through an extender cable. Operating the spectrum analyzer outside the mainframe in this manner exposes high voltage points in the instrument that will, if contacted, cause personal injury. Maintenance and repair of this instrument should, therefore, be performed only by a skilled person who knows the hazards involved. Where maintenance can be performed without power applied, the power should be removed. When any repair is com- pleted, be sure that all safety features are intact and functioning and that all necessary parts are connected to their positive grounds.

8-3.SCHEMATIC SYMBOLS, TERMINOLOGY, AND VOLTAGELEVELS

8-4. Symbols and terminology used on the schematic diagrams are explained in Figure 8-1. Test conditions for the signal and dc voltage levels shown on the block and schematic diagrams are provided in Figure 8-2.

the listed instrument is not available, another instrument that meets the required minimum specifications may be substituted.

8-7. MAJOR ASSEMBLY LOCATIONS

8-8. The major assembly location illustrations for the spectrum analyzer are located near the end of this section.

8-9.TROUBLESHOOTING8-10. GeneralInformation

8-11.Troubleshooting is most easily accomplished by using the block diagram at the end of this section to follow the signal path. Once the problem is isolated to a particular circuit, the circuit description and schematic diagram can be used to locate the faulty component.

NOTE

When a part is replaced, adjustment of the affected circuitry is usually required. For adjustment procedures, refer to Section V.

8-5. TEST EQUIPMENT

8-6.Test instruments and accessories used to maintain the spectrum analyzer are listed in Table 1-4. If

Improper cleaning of the printed circuit board edge connectors can cause damage to the contact'sgold plating, resulting in corrosion and intermittent electrical contact. Use only the recommendedprocedure.