Replacing the fuse | Agilent Technologies U1251A instruction

5 Maintenance

4To test Fuse 2, place and touch the tip of the test probe on the right half of input terminal . Ensure that the probe tip touches the metal inside the input terminal.

5Observe the reading on the instrument's display. Refer to Table 5- 3 for the possible readings that could appear).

6Replace the fuse when OL is displayed.

Table 5-3Measurement readings for fuse checking

	Current input terminal	Fuse	Fuse rating	Fuse OK (approximately)	Replace fuse

				Displayed readings
				Displayed readings

		1	440 mA/1000 V	6.2 MΩ	OL

		2	11 A/1000 V	0.06 Ω	OL

Replacing the fuse

N O T E

This manual provides only the fuse replacement procedures, but not the fuse replacement markings.

Follow the procedures below to replace the fuse.

1Turn the meter off and disconnect the test leads from the external equipment. Make sure to remove the adaptor.

2Wear clean/dry gloves and do not touch any other component except the fuse and plastic parts. The current calibration is considered shunt only, so do not recalibrate the meter after replacing the fuse.

3Remove the battery cover compartment to replace the fuse.

4Loosen the three screws on the bottom case and remove the cover.

5Loosen the two screws on the top corners to lift the circuit board.

106	Agilent U1251A/U1252A User’s and Service Guide

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Agilent Technologies U1251A manual Replacing the fuse, 3Measurement readings for fuse checking

Contents

Agilent U1251A U1252A Handheld Digital Multimeter U T I O N WA R N I N G Safety Symbols Safety Information WA R N I N G Never measure voltage when current measurement is selected Meter, and follow the correct polarity Regulatory Markings Product Category Affixed product label is as shown below This Guide… Declaration of Conformity DoC Contents Setting Percentage % Scale Readout Overload alert Adjustment is recommended Returning to Default Factory SettingsAgilent Technologies calibration services Calibration interval Adjustment procedure Adjustments ConsiderationValid adjustment input values Calibration errors 161 III Xviii List of Figures Reset setup List of Tables 159 Getting Started Introducing the U12521A/U1252A Handheld Digital Multimeter Introducing the U12521A/U1252A Handheld Digital Multimeter Check the shipment Adjusting the tilt-stand IR-USB cable To PC host Tilt-stand at 3Tilt-stand at hanging position Display Keypad Rotary switch Terminal Connectors Front panel at a glance Tilt-stand Battery access cover Rear panel at a glanceIR communication port Rotary switch at a glance 7U1252A keypad 2Keypad desciption and functions Button Sets to Auto Range mode Display at a glance 3General display symbols LCD symbol Description 4Priamry display symbols 5Secondary display symbols KHz 6Analog bar range and counts 2500 Diode Ω, nSRange Counts/segments Used for the function Selecting display with the Hz button Hz Frequency counter press Frequency Hz Pulse width ms 7Selecting display with the Hz button Frequency HzDuty cycle % Frequency Hz Duty cycle % Hz Frequency counter press Frequency Hz 100 By pressing Selecting display with the Dual button8Selecting display with the Dual button For U1251A AC a Hz AC coupling Rotary switch position Function Primary displaySelection display with the Shift button 9Selecting display with the Shift button 9Selecting display with the Shift button For U1252A DC mV Temp Rotary switch position Input terminals Overload protection Terminals at a glance Making Measurements Understanding The Measurement Instructions Understanding The Measurement Instructions 1Numerical steps descriptionsNo.Instructions Measuring AC voltage Red Lead Black Lead Measuring DC voltage 2Measuring DC voltage Measuring Current ΜA & mA measurementPress If necessary to ensure Black Lead Red Lead 3Measuring μA and mA current Percentage scale of 4 mA to 20 mA Press2Percentage scale and measurement range 4Measuring scale of 4-20 mA Ampere measurement 5A ampere current measurement Frequency Counter 6Measuring frequency Measuring Resistance, Conductance and Testing Continuity Audible continuity 8Audible continuity, conductance, and resistance test 3Audible continuity measurement range Measurement range Beeper sound threshold 9Conductance measurement Testing Diodes 10Measuring forward bias of diode 11Measuring reverse bias of diode Measuring Capacitance Means the capacitor is charging Discharging 12Capacitance measurements Measuring Temperature 14Connecting the probe with adapter into the multimeter Making Measurements 15Surface temperature measurement Alerts and Warning During Measurement Overload alertInput warning Charge terminal alert 17Charge terminal alert Functions and Features Dynamic Recording Press to restart the dynamic recording 1Dynamic recording mode operation 2Data hold mode operation Data Hold Trigger Hold Refresh Hold Press to return Null Relative 4Null relative mode operation Decibel Display Reference for other voltage measurements 5dBm/dBV display mode operation Press Pres s To re-start the peak-recording measurement Ms Peak HoldIf the reading is OL, press If you need to re-start the peak recording, press 61 ms peak hold mode operation Data Logging Manual logging Full Log Interval logging Are filled, Full is indicated on the secondary display 9Interval Automatic logging mode operation Reviewing logged data 10Log review mode operation Square Wave Output for U1252A Frequency Hz 11Frequency adjustment for square wave output Press 13Duty cycle adjustment for Square Wave Remote Communication Connect To PC Features and Functions Changing The Default Setting Setting Data Bit Selecting Setup Mode 1Available setting options in Setup mode Menu Item Available setting optionsDisplay Description Swaps display to C Setting Data Hold/Refresh Hold Mode 1Data hold/Refersh hold setup Setting Data Logging Mode Press PressPress Setting Thermocouple Types U1252A only 3Thermocouple type setup Setting Reference Impedance for dBm Measurement 4Reference impedance for dBm measurement setup Setting Minimum Frequency Measurement 5Minimum frequency setup Setting Temperature Unit 6Temperature unit setup Setting Auto Power Saving Mode 7Auto power saving setup Setting Percentage % Scale Readout % scale readout setup Setting Beep Frequency 9Beep frequency setup Setting Backlight Timer 10Backlit timer setup Setting Baud Rate 11Baud rate setup remote control Setting Parity Check 12Parity check setup Setting Data Bit 13Data bit setup for remote control Setting Echo Mode 14Echo mode setup for remote control Setting Print Mode 15Print mode setup for remote control Returning to Default Factory Settings Press Press Maintenance General maintenance Battery replacementIntroduction List of compatible batteries for the Agilent U1251A List of of compatible batteries for the Agilent U1252ANominal voltage Charging the battery Storage considerationsMultimeter is to be unused for long periods of time U T I O N 2Battery capacity display as trickle Condition Battery voltage Proportional percentage 2Error messages Error Error message 4Charging mode Agilent U1251A/U1252A User’s and Service Guide 103 6Battery charging procedure Fuse checking procedure Figure above Replacing the fuse 3Measurement readings for fuse checking 4Fuse specifications FuseFuse Agilent part number Rating Size Type Troubleshooting 5Basic troubleshooting proceduresMalfunction Troubleshooting procedure Replaceable Parts To order replaceable parts 110 Agilent U1251A/U1252A User’s and Service Guide Closed- case electronic calibration Backlit testCurrent terminal test Agilent Technologies calibration services Calibration OverviewClosed-case electronic calibration Adjustment is recommended Calibration interval Recommended Test Equipment 1Recommended Test EquipmentApplication Recommended equipment Testing the display Basic Operating TestBacklit test Setup Current terminal test Charge terminal alert test Test Considerations Calibration Security Performance Verification Tests Doing the performance verification tests Error from nominal 1 year 2Performance verification test stepsStep Test Function Range U1251A ± 20 mV ± 17.5 mV 500 ± 200 mV 1000 ± 800 mV Agilent U1251A/U1252A User’s and Service Guide 123 ± 75 μV ± 350 mW 33250A Output Step Test Function Range 5520A Output Square Wave Use 53131A Output Use 34410A Agilent U1251A/U1252A User’s and Service Guide 127 Unsecuring the instrument for calibration To Unsecure the Instrument from the Front Panel Agilent U1251A/U1252A User’s and Service Guide 129 Tory default code using the front panel Calibration process Using the front panel for adjustments Selecting the Adjustment Mode Adjustments Consideration Problem and repeat the procedureCalibration memory for the present function Valid adjustment input values 3Valid adjustment input valuesFunction Range Valid Amplitude Input Values Adjustment procedure Simultaneously to exit the adjustment mode 136 Agilent U1251A/U1252A User’s and Service Guide 4Adjustment table Step Test Function Cal Range Input Cal Item U1251A U1252A 138 Agilent U1251A/U1252A User’s and Service Guide Agilent U1251A/U1252A User’s and Service Guide 139 Open Agilent U1251A/U1252A User’s and Service Guide 141 Finishing the adjustment To read the calibration countYour instrument was calibrated before it left the factory Calibration errors Number Recommended Accuracy Requirements 144 Agilent U1251A/U1252A User’s and Service Guide Frequency Sensitivity Specifications Frequency Counter Specifications for U1252A Product Characteristics Power Supply Agilent U1251A/U1252A User’s and Service Guide 147 Calibration Cycle Measurement Category Measurement category definition Specification Assumptions Function Range Resolution Burden Voltage U1251A U1252A Electrical SpecificationsDC Specifications Accuracy Maximum open voltage + 4.2 AC Specifications Frequency Function Range Resolution Frequency 20 Hz 45 Hz KHz 10 kHz Function Range Resolution 45 Hz KHz 10 kHz 20 kHzFunction Range Resolution Frequency Hz 45 Hz 7U1252A true RMS ac+dc current specifications Function Range Resolution 45 Hz KHz 10 kHzFrequency 30 Hz 45 Hz KHz 8Capacitance specifications Capacitance SpecificationsTemperature Specifications 9Temperature specifications 10Frequency specifications Frequency SpecificationsDuty Cycle and Pulse Width Specifications 11Duty cycle and pulse width specifications Model Number U1251A U1252A Frequency Sensitivity SpecificationsMinimum sensitivity RMS sine wave 100 kHz Peak Hold Specifications Signal Width Accuracy For DC mV/voltage/currentInput Range 16Frequency counter divide by 100 4 specifications Frequency Counter Specifications for U1252A15Frequency counter divide by 1 specifications Sensitivity Min. Input Frequency 17Square wave output specifications Square Wave Output for U1252AOutput Range Accuracy 18Display update rate approximate Operating SpecificationsDisplay update rate approximate Realtime clock. Only ONE sample per second can be logged Input impedance 19Input Impedance 164 Agilent U1251A/U1252A User’s and Service Guide Contact us