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SERVICE MANUAL
AUTORANGING
DC POWER SUPPLY
AGILENT MODELS
6023A and 6028A
Agilent Part No. 5964-8283
FOR INSTRUMENTS WITH SERIAL NUMBERS
Agilent Model 6023A; Serials US36490101 and above
Agilent Model 6028A; Serials US36520101 and above
For instruments with higher serial numbers, a change page may be included.
Microfiche Part No. 5964-8284 Printed in USA: July 2001
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CERTIFICATION Agilent Technologies certifies that this product met its published specifications at time of shipment from the factory. Agilent Technologies further certifies that its calibration measurements are traceable to the United States National Institute of Standards and Technology, to the extent allowed by the Institute’s calibration facility, and to the calibration facilities of other International Standards Organization members. WARRANTY This Agilent Technologies hardware product is war
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SAFETY SUMMARY The following general safety precautions must be observed during all phases of operation, service and repair of this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design, manufacture, and intended use of the instrument. Agilent Technologies, Inc. assumes no liability for the customer's failure to comply with these requirements. BEFORE APPLYING POWER. Verify that the product is set to match the a
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SAFETY SYMBOL DEFINITIONS Symbol Description Symbol Description Direct current Terminal for Line conductor on permanently installed equipment Alternating current Caution, risk of electric shock Both direct and alternating current Caution, hot surface Three-phase alternating current Caution (refer to accompanying documents) Earth (ground) terminal In position of a bi-stable push control Protective earth (ground) terminal Out position of a bi-stable push control Frame or chassis terminal On (suppl
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TABLE OF CONTENTS Introduction ............................................................................................................................................................................7 Scope ....................................................................................................................................................................................7 Calibration and Verification ..............................................................................
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Overvoltage Protection (OVP) Circuit............................................................................................................................49 Power-Limit Comparator................................................................................................................................................49 Control-Voltage Comparator ..........................................................................................................................................49
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1 Introduction Scope This manual contains information for troubleshooting the Agilent 6023A or 6028A 200W Autoranging Power Supply to the component level. Wherever applicable, the service instructions given in this manual refer to pertinent information provided in the Operation Manual. Both manuals cover Agilent Models 6023A/28A; differences between models are described as required. The following information is contained in this manual. Calibration and Verification Contains calibration procedur
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Manual Revisions Agilent Technologies instruments are identified by a 10-digit serial number. The format is described as follows: first two letters indicate the country of manufacture. The next four digits are a code that identify either the date of manufacture or of a significant design change. The last four digits are a sequential number assigned to each instrument. Item Description US The first two letters indicates the country of manufacture, where US = USA; MY = Malaysia. 3648 This is a cod
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2 Calibration and Verification Introduction This section provides test and calibration procedures. The operation-verification tests comprise a short procedure to verify that the unit is performing properly, without testing all specified parameters. After troubleshooting and repair of a defective power supply you can usually verify proper operation with the turn-on checkout procedure in the Operating Manual. Repairs to the A1 main board and the A2 control board can involve circuits which, althoug
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Table 2-1. Test Equipment Required TYPE REQUIRED CHARACTERISTICS USE RECOMMENDED MODEL Oscilloscope Sensitivity: 1 mV P,T Agilent 1740A Bandwidth: 20MHz & 100MHz Input: differential, 50Ω & 10MΩ RMS Voltmeter True rms, 10MHz bandwidth P Agilent 3400B Sensitivity: 1 mV Accuracy: 5% Logic Pulser 4.5 to 5.5Vdc @ 35mA T Agilent 546A Multimeter Resolution: 100nV P,A,T Agilent 3458A Accuracy: 0.0035%, 6½ digit CC PARD Test No saturation at 30Adc P Tektronix P6303 Current Probe Bandwidth: 20Hz to 20MHz
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Table 2-1. Test Equipment Required (continued) TYPE REQUIRED CHARACTERISTICS USE RECOMMENDED MODEL Switch SPST, 30A @ 20V P DC Power Supply Voltage range: 0-60Vdc T,P Agilent 6296A Current range: 0-3Adc Variable Voltage Range greater than -13% to +6% of P,A Transformer nominal input AC voltage (autotransformer) 1KVA P = performance testing A = calibration adjustments T = troubleshooting * Resistors may be substituted for test where an electronic load is not available. ** Less accurate, and les
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Table 2-2. Calibration Procedure TEST TESTED TEST POINTS TEST SEQUENCE AND ADJUSTMENTS EXPECTED VARIABLE RESULTS Meter F/S Meter Ref. A2J3 pin 6 ( + ) a. Connect DVM across test points and turn on 0.5V ± 50µ V Adjust. Voltage M ( - ) ac power. b. Adjust A2R24 to obtain the voltage range specified in the results. Resistance Prog. Voltage VP ( + ) a. Connect a 2KΩ 0.01%, ¼W programming 2.5V ±4mV Programming P ( - ) resistor and DVM between test points. F/S b. Set MODE switch as in Figure 2-1 and
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Table 2-2. Calibration Procedure (continued) TEST TESTED TEST POINTS TEST SEQUENCE AND ADJUSTMENTS EXPECTED VARIABLE RESULTS Power V(OUT) a. Perform I-MON F/S Adjust before 30.2A 7.55V for Limit I(OUT) proceeding. CC operation Adjust. b. Connect the unit to the ac power line via the (6023A) external variable auto-transformer which is set to nominal line voltage. 10.2A, 23V for CC operation c. Connect a 0.25Ω , 250W (6023A), 2.3Ω , 250W (6028A) resistor across the unit's output (6028A) and turn
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Table 2-3. Guide to Recalibration After Repair Printed Circuit Block Name Circuit Within Ref. Perform These Board Block Designator Procedures* A1 Main Board R3 4 A1 Main Board T1 4 then 5 A4 Power Mesh T3 4 then 5 Board A4 Power Mesh CR7 4 then 5 Board A2 Control Board Constant Voltage All Except Current All 1 then 2 (CV) Circuit Source A2 Control Board Constant Voltage Current Source All 6 (CV) Circuit A2 Control Board Constant Current All 3 then 4 (CC) Circuit A2 Control Board Power Limit All
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The substitution of the load resistor requires adding a load switch to open and short the load in the CC or CV load regulation tests. The load transient recovery time test procedure cannot be performed using load resistors. An electronic load is considerably easier to use than a load resistor. It eliminates the need for connecting resistors or rheostats in parallel to handle the power, it is much more stable than a carbon-pile load, and it makes easy work of switching between load conditions as
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Figure 2-3. Basic Test Setup d. Reduce the resistance of the load to draw an output current of: 29Adc (6023A) 10Adc (6028A) Check that the unit's CV LED remains lighted. e. Record the output voltage at the digital voltmeter. f. Open-circuit the load. g. When the reading settles, record the output voltage again. Check that the two recorded readings differ no more than: ± 0.0027Vdc (6023A) ± 0.0090Vdc (6028A) Source Effect (Line Regulation). Source effect is the change in dc output vol
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f. Record the output voltage at the digital voltmeter. g. Adjust autotransformer to the maximum for your line voltage. h. When the reading settles record the output voltage again. Check that the two recorded readings differ no more than: ± 0.0030Vdc (6023A) ± 0.0080Vdc (6028A) PARD (Ripple And Noise). Periodic and random deviations (PARD) in the unit's output-ripple and noise-combine to produce a residual ac voltage superimposed on the dc output voltage. Constant-voltage PARD is specified as th
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the unit's output voltage. To reduce common-mode noise pickup, set up the oscilloscope for a differential, two-channel voltage measurement. To reduce normal-mode noise pickup, use twisted, 1 meter or shorter, 50Ω coaxial cables with shields connected to the oscilloscope case and to each other at the other ends. Proceed as follows: a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set resistance to maximum. b. Turn the unit's power
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6023A 6028A Figure 2-6. 20KHz Noise, CV Peak-to-Peak PARD Load Transient Recovery Time. Specified for CV operation only; load transient recovery time is the time for the output voltage to return to within a specified band around its set voltage following a step change in load. Proceed as follows: a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant-current mode and set for minimum current. b. Turn the unit's power on, and turn up current setting to full output. c.
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6023A 6028A Figure 2-7. Load Transient Recovery Waveform Temperature Coefficient. (6023A) Temperature coefficient (TC) is the change in output voltage for each °C change in ambient temperature with constant ac line voltage, constant output voltage setting and constant load resistance. Measure temperature coefficient by placing the unit in an oven, varying the temperature over a range within the unit's operating temperature range, and measuring the change in output voltage. Use a
