HP 1GSa/s Digitizing Oscilloscope 16532A manual Introduction Safety Requirements, Acquisition

Page 67

HP 16532A - Service

6-1. Introduction

The service policy for this instrument is replace- ment of defective assemblies. This service manual contains information for finding a defective assembly. This section contains information for servicing the HP 16532A Oscilloscope Module. Included are a block level theory and procedures for self diagnostics and troubleshooting. If the module or a cable is determined faulty, procedures are provided for module and cable replacement.

6-2. Safety Requirements

Specific warnings, cautions, and instructions are placed wherever applicable throughout the manual. These must be observed during all phases of operation, service, and repair of the module. Failure to comply with them violates safety standards of design, manufacture, and intended use of this module. Hewlett-Packard assumes no liability for the failure of the customer to comply with these safety requirements.

6-3. Recommended Test Equipment

Table 1-3 lists recommended test equipment. Any equipment that satisfies the critical specification given in the table may be substituted for the recommended models.

SECTION VI

Service

6-5. Attenuator Theory of Operation

The channel signals are conditioned by the attenuator/preamps, thick film hybrids containing passive attenuators, impedance converters, and a programmable amplifier. The channel sensitivity defaults to the standard 1-2-4 sequence (other sensitivities can be set also). However, the firmware uses passive attenuation of 1, 5, 25, and 125, with the programmable preamp, to cover the entire sensitivity range.

The input has a selectable 1 MΩ input impedance with ac or dc coupling or a 50Ω input impedance with dc coupling. Compensation for the passive attenuators is laser trimmed and is not adjustable. After the passive attenuators, the signal is split into high-frequency and low-frequency components. Low frequency components are amplified on the main assembly, where they are combined with the offset voltage. The ac coupling is implemented in the low frequency amplifier.

The high- and low-frequency components of the signal are recombined and applied to the input FET of the preamp. The FET provides a high input impedance for the preamp. The programmable preamp adjusts the gain to suit the required sensitivity and provides the output signal to the main assembly. The output signal is then sent to both the trigger circuitry and ADC.

6-4. Module Block Diagram and The- ory of Operation

The following paragraphs contain block level theory of operation. This theory is not intended for component level troubleshooting, rather it is to be used to help isolate a module failure to card level.

The HP 16532A Oscilloscope Module is contained on one board. It runs at a 1 GSa/s digitizing rate, with a 250 MHz single-shot (real-time) bandwidth, 8000 samples per measurement per channel, with 2-channel simultaneous acquisition which is expandable to up to 8 channels. See figure 6-1.

6-6. Main Assembly Theory of Operation

Acquisition

The acquisition circuitry provides the sampling, digitizing, and storing of the signals from the channel attenuators. The channels are identical. The external trigger (ECL) input cannot be displayed. Trigger signals from each channel and the external triggers synchronize acquisition through the time base circuitry. A 100 MHz oscillator and a time base provide system timing and sample clocking. A voltage-controlled oscillator (VCO), frequency divider, and digital

6-1

Page 66 Page 68
Image 67
Page 66 Page 68
Contents HP 16532A Safety Symbols Safety ConsiderationsContents Calibration ServiceSection Replaceable Parts List of Tables Page Table of Contents Page Introduction Safety RequirementsModule Covered by This Manual Operating Characteristics Accessories SuppliedAccessories Available SpecificationsVertical dc Gain Accuracy4 ± 1.5% of full scale HP 16532A SpecificationsRise Time2 1.4 ns Waveform Record Length 8000 pointsVertical at BNC HP 16532A Operating CharacteristicsTimebase Trigger Modes TriggeringDigitizer Trigger Level RangeDisplay Modes Waveform DisplayMeasurement Aids Operating Environment Setup AidsEquipment Critical Specifications Recommended Model USE Page Table of Contents Page Preparation for Use Power RequirementsInitial Inspection Safety Requirements Module InstallationProcedure Installation ConsiderationsEndplate Overlap Bottom Sequence Packaging Tagging for ServiceOperating Environment StorageTable of Contents Page Test Record Performance Test ProceduresPerformance Test Interval DC CAL Output Test AC CAL Output Test Equipment Required Critical Specification Model/Part Number SpecificationInput Resistance Page Voltage Measurement Accuracy Voltage Measurement Accuracy Test Div Offset Supply Upper Limit Lower Limit Offset Accuracy Procedure Zero-Input OffsetDiv Offset Supply Min Max DC Input OffsetBandwidth V1MHz Time Measurement Accuracy Menu Selection Setting Trigger Sensitivity RUN Repetitive Performance Test Record Paragraph No Test Results Yes No Page Table of Contents Page Calibration Interval Calibration Protection SwitchMaintaining System Integrity Calibration Instrument WarmupLocation of the PROTECT/UNPROTECT Switch Setting the PROTECT/UNPROTECT Switch to UnprotectEquipment Required for Calibration Loading the Default Calibration FactorsSelf Cal Menu Calibrations Calibrate Delay of the Self Cal menu as followsCalibrate Vert Cal of the Self Cal menu as follows Calibrate the Logic Trigger of the Self Cal menu as follows Calibrate the Time Null of the Self Cal menu as followsExt Trig Null Calibration Connections Calibrate the Ext Trig Null of the Self Cal menu as followsSealing the Mainframe Setting the PROTECT/UNPROTECT Switch to ProtectTable of Contents Page Exchange Assemblies Replaceable Parts ListAbbreviations Ordering InformationDirect Mail Order System Reference Designator and Abbreviations Parts Identification Mfr Code Mfr Part Number Reference DesignatorHP Part Qty Number DescriptionPage Table of Contents Page Attenuator Theory of Operation Introduction Safety RequirementsModule Block Diagram and The- ory of Operation Main Assembly Theory of OperationHP 16532A Oscilloscope Block Diagram Page Self-Tests Self-Test Access ProcedureLoad Test System Screen Touch the Functional Tests field Functional Tests ScreenA/D Test Run Screen Exit Test System Screen Test Self-Test DescriptionsData Memory Test Timebase TestTroubleshooting Aids TroubleshootingVerifying the System Clock Page Troubleshooting Sheet Troubleshooting E E T1 6 5 3 2 a Troubleshooting E E T Troubleshooting E E T Troubleshooting E E T Troubleshooting E E T Oscilloscope Module Removal Procedure Oscilloscope Module Removal and Replacement12. Endplate Overlap Bottom Sequence Oscilloscope Module Replacement ProcedureTrigger Cable Removal Procedure Trigger Cable Removal and ReplacementTrigger Cable Replacement Procedure Attenuator Removal and ReplacementAttenuator Removal Procedure Attenuator Replacement Procedure Certification WarrantyAssistance
Top Page Image Contents