HP-405C-CR-Manual 电路图.pdf

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1、I . : HP Archive . . This vintage Hewlett Packard document was preserved and distributed by www. Please visit us on the web ! . . On-line curator: Tony Gerbic RadioFans.CN 收音机爱 好者资料库 OPERATING A N D SERVICING M A N U A L HP Part No. 405C-901 MODEL 405C/CR SERIALS PREFIXED: 243-, 402- 219-, 120-, 114

2、-, 101- DI AUTO GITAL M V ATIC DC OLTMET ER 1961 Copvriohl HEWLETT-PACKARD COMPANY 1501 PAGE MILL ROAD, P A L 0 ALTO, CALIFORNIA, U.S.A. 0051 8- 3 v Printed IUME 1963 RadioFans.CN 收音机爱 好者资料库 Table of Contents Lists of Illustrations and Tables Model 405C Section TABLE OF CONTENTS Page Section I GENER

3、ALDESCRIPTION . 1-1 III 1 . 1 . Identification . 1-1 1.2 . Cooling . 1-1 1.3 . Stepping Switch . 1-1 1.5 . Three Conductor Power Cable . 1-1 1.4 . Power Line Voltage . 1-1 Iv II OPERATING INSTRUCTIONS . 2-1 2.1 . Automatic Operation . 2-1 2.2 . Manual Operation . 2-1 2.3 . Calibration . 2-1 2.4 . In

4、put Filter . 2-2 2.5 . Operation with Digital Recorders . 2-2 2.6 . Electrical Output Information . 2-3 III THEORY OF OPERATION . 3-1 3.1 . Introduction . 3-1 3.2 . Input Circuit . 3-1 V 3.3 . Voltage-to-Time Conversion . 3-1 3 . 4 . Zero-Setting the Voltmeter . 3-2 3.5 . The Measurement Process . 3

5、-2 Page . THEORY OF OPERATION (Contd) 3.7 . Decimal Shift Control . 3-3 3.6 . Checking Range . 3-2 4.1 . Introduction . 4-1 4 . 2 . Test Equipment . 4-1 4.3 . Performance Check . 4-1 4.4 . Cabinet Removal . 4-2 4.5 . Power Supplies . 4-2 4.6 . Balancing the Amplifier . 4-2 4 . 7 . Neutralizing the A

6、mplifier . 4-3 4.8 . 405A-95C Adapter Adjustment . 4.3 4.9 . Stepping SwitchMaintenance . 4-3 4.10 . Tube and Diode Replacement . 4-3 4 . 1 1 . Trouble shooting 4-5 . REPLACEABLE PARTS . 5-1 5.1 . Table of Replaceable Parts . 5-1 5.3 . Ordering Information . 5-1 5.2 . Digital Recorder Adapter. 405A-

7、95C . 5-1 LIST OF ILLUSTRATIONS Figure Page Figure 1 . 1 . Model 405CR, Automatic DC Digital 4.6 . Voltage and Resistance Diagram. 4.7 . Voltage and Resistance Diagram. Voltmeter V1 through V9 . . 1 . 1 3.1 . Model 405 C Biock Diagram . 3-0 4.1 . Stepping Switch Lubrication Diagram . 4-4 4.8 . Power

8、 Supply . 4 . 2 . Troubleshooting Waveform Time 4.9 . hplifier/Oscillator Section . Sequence . 4-8 4- 10 . Control/Counter Section . 4.3 . Ranging Troubleshooting Waveforms . 4-9 4.11 Stepping Switch V10 through V18 . . . 4.4 . Top Internal View of Model 405C . 4-10 4.12 . Polarity Relay Wiring . 4.

9、5 . Bottom Internal View of Model 405C . 4-11 4.13 . 405C-95C Digital Recorder Adapter . LIST OF TABLES Table Page 1 . 1 . Specifications . 1-0 2.1 . 53 Output Connector Chart . 2-3 4.1 . Troubleshooting Aid . 4-4 4.2A . Waveforms . 4-6 4.2B . Troubleshooting the Amplifier . 5.1 . Replaceable Parts

10、. 5-1 5 . 2 . Digital Recorder Adapter, Model 405A-95C . 5- 13 4-7 Page 4-13 4-14 4-15 4-16 4-17 4-18 4-19 4-20 00518-2 iii RadioFans.CN 收音机爱 好者资料库 Model 4052 Sect.1 Page 1 i : 1-1 IDENTIFICATION The 6 3 Model 405C Automatic DC Digital Voltmeter measures positive or negativevoltages from 1 milli- vo

11、lt to 999 volts. It can select range and polarity automatikally to display voltages from 100 milli- volts to 999 volts to three significant figures. 1-2 COOLING The 405C uses forced-air cooling to maintain tol- erable temperatures within the cabinet. Exhaust fan and air outlet are located on the ins

12、trument rear air intakes, on the sides. Allow at least 2 in. clear- ance about instrument sides and rear for proper ventilation. 1-3 STEPPING SWITCH The 405C uses a relax-operated stepping switch for ranging. Although the switch requires infre- quent service, it is important to -service it when due.

13、 See Section IV, Maintenance. 1-4 POWER LINE VOLTAGE The405C is normally wired for use from a 115-volt, 50-60 cps power source. To convert it for use from a 230-volt power source, change the dual 115-volt primarywindings of the power transformer from a *- GENERAL DESCRIPTIO parallel combination to a

14、 series combination. See the schematic diagram for details. At the time of conversion, change the line fuse from a 2-ampere, slow-blow type to a 1-ampere, slow-blow type. 1-5 THREE CONDUCTOR POWER CABLE This instrument is equipped with a three conductor power cable terminated with a polarized connec

15、tor recommended by the National Electrical Manufac- turers Association (NEMA). The third green conductor is terminated in a round pin added to a standard two-bladeconnector. With the NEMA con- nector plugged into an appropriate receptacle, the third lead grounds the instrument cabinet for the protec

16、tion of operating personnel. To use the NEMA connector in a two-contact receptacle, you should use a three-prong to two-prong adapter. The ground lead emerges from the adapter as a short green lead which should be connected to a grounded receptacle box. 1-6 DAMAGE IN SHIPMENT Inspect and operate thi

17、s instrument upon receipt. Section IV contains a performance check which is a good test as part of incoming quality control inspec- tion. If there is any damage, see theC1aim or Damage in Shipment sheet in this manual. i Figure 1-1. Model 405CR Automatic DC Digital Voltmeter 00518- 2 Section I Page

18、0 Table 1-1. Specifications Model 405C RANGE : . 001 to 999 volts dc. Voltages 100 mvandhigher are presented by three significant figures. ACCURACY: Within kO. 2% of reading +I count. FLOATING INPUT: Permits measurements of systems operating within *500 vdc of power line ground. RANGE ANI) POLARITY

19、SELECTION: Automatic. A hold controldisables the automatic selection and permits manual range selection. RANGING TIME: 1/5 second to 2 seconds depending on range change required. INPUT IMPEDANCE: 11 megohms to dc on all ranges. INPUT FILTER RESPONSE TIME: Less than 1 second to step function. 3 db a

20、t 1.5 cps, nominally 44 db at 60 cps INPUT FILTER AC REJECTION: DIMENSIONS: T- TOP WEIGHT: Net 31 lbs. Shipping 46 lbs. SAMPLE RATE: Internal: Maximum, more than 4 but less than 5 per second Minimum, 5 seconds or more between samples External: By 20 volt positive pulse, maximum rate of 5 per second

21、OUTPUT : 1) 10-line decimal code for operating Model 561B Digital Recorder or K05-405A Remote Indicator. 2) Single-line voltage coded decimal (staircase). For operating Model 560A Digital Recorder, use the 405A-95C Adapter. 3) A print command for Digital Recorders is issued after every sample except

22、 when the 405CR is ranging. HOLD-OFF: Internal hold-off circuitwill operate from an ex- ternal contact-closure. INPUT CONNECTORS: Front panel: Input: 3 binding posts Rear panel: Sync Input: BNC Input: MS 3102A-lOSL-3P ACCESSORIES AVAILABLE : 405A-95C Adapter, permits direct connection to Model 560A

23、Digital Recorder. COMPLEMENTARY EQUPMENT: 561B Digital Recorder; operates from 10-line decimal code. 560A Digital Recorder; operates from staircase code. K05-405A Remote Indicator KO?-405A Cable (100 ft max) for connecting K05- 405A to 405CR. 00 518 -3 Model 405C Sect.11 Page 1 2-1 AUTOMATIC OPERATI

24、ON 1) Turn instrument ON. Instrument can be used within 1 minute of turn on, but requires 15 minutes warm up before calibration against internal stand- ard brings it within specified accuracy. See para- graph 2-3. 2) Set RANGE switch to AUTO. 3) Set SAMPLING control to desired sampling rate. To cont

25、rol sampling rate externally, set SAMP- LING control to EXT and connect triggering signal to EXT TRIGGER connector on instrument rear. Trigger must be a positive step at least 20 volts peak and have repetition rate no greater than 5 per second. NOTE The instrument requires about 1 second to fully re

26、- spond to sudden input-voltage changes (see para- graph 2-4); therefore delay the external trigger about 1 second after any sudden change in applied voltage. - - - - - - 4) Connect voltage to be measured to INPUT con- nector and read its value. A parallel INPUT con- nector is located on instrument

27、rear. CAUTION When measuring voltage between two points which are both off ground potential, remove the shorting strap between power-line ground and chassis- ground terminals of front-panel INPUT connector. - 2-2 MANUAL OPERATION Manual operation permits manual selection of range and is intended for

28、 measuring voltages which pro- duce readings of 999 or 100 regardless of decimal position. In either case, a varying input voltage might cause the instrument to continuously change ranges if .it is operating automatically. 0 PER AT1 NG INSTRUCTIONS Manual operation permits measurement of some voltag

29、es to four figures, for the instrument can measure to about 150% of full scale. By holding the instrument on the range just below the correct range, you obtain the second, third, and fourth figures from the readout; the first figure, which is lost, is always 1. However, instrument accu- racy deterio

30、rates above full scale. Manual operation is convenient for measuring a series of voltages quite close in value, for the in- strument will not cycle through its ranges as you move the probe from one test point to another. 1) Set RANGE switch to HOLD. Instrument will remain on its displayed range. 2)

31、To change ranges, set RANGE switch to STEP. This is a spring-loaded position, and switch returns to HOLD when released. Instrument steps to next more positive range each time you release RANGE switch from STEP except that three blank positions occur between +9.99 and +99.9 volt ranges. The decimal p

32、oint is not lighted on the blank ranges. 2-3 CALIBRATION The 405C has an internal secondary voltage stand- ard to check its calibration. The push-button CALIBRATE switch, located on the front panel, applies this voltage to the instrument and discon- nects the INPUT connector. Calibrate the instru- m

33、ent, after sufficient warm up, each time you turn it on. Once set, calibration need seldom be checked. Proceed as follows: 1) Turn instrument ON and allow 15 - minute warm up. 2) Set SAMPLING control to maximum sampling rate (full clockwise but not to EXT). 3) Set RANGE switch to AUTO. 4) Note volta

34、ge indicated below CALIBRATE en- graving on front panel. This is the internal second- ary standard voltage. 00518-1 Sect.11 Page 2 Voltmeter Indication + 3.48 + .283 - 565. Model 405C , Printed Record 348 2 283 3 565-0 5) Press CALIBRATE switch and adjust CALI- BRATE control until readout agrees wit

35、h internal secondary standard voltage. 2-4 INPUT FILTER The 405C measures instantaneous dc voltages. To avoid readout variations due to superimposed ac signals, the instrument has a low-pass RC filter at its input. The filter has a sharp cutoff and attenuates 60-cps signals about 50 db. Thus a 60-cp

36、s signal with a peak value equal to full scale of the displayed range typically causes a readout variation of * 4 counts. Since the filter is at the input, it becomes charged to the full value of the input voltage. With the in- put open-circuited (probe lifted off test point), the filter capacitors

37、must discharge through the input attenuator, and after 2 seconds they still haveabout 37% of their original charge. (Youcansee the dis- charge by watching the readout decrease after the probe is removed from a voltage source.) There- fore, if you quickly change the probe from a high- voltage point t

38、o a low-voltage point, you will apply nearly the full high voltage stored in the filter capacitors to the low-voltage point through 500K resistance. If the low-voltage point happens to be a high-impedance point such as a vacuum tube grid or, possibly, a transitor element, the voltage ap- plied throu

39、gh the probe may upset circuit oper- ation to the point that the circuit will damage itself. A GOOD OPERATING PRACTICE IS TO TOUCH THE PROBE TO GROUND BRIEFLY OR ALLOW THE FILTER SUFFICIENT TIME TO DISCHARGE WHEN CHANGING THE PROBE FROM HIGH- VOLTAGE POINTS TO LOW-VOLTAGE POINTS. In any case be sure

40、 the readout is less than the expected voltage before connecting the probe into a low-voltage circuit. The input filter makes instrument response to step functions about 0.75 second compared to about 0.2 second between successive samplings at maximum sampling rate. If you require a response time com

41、patible with maximum sampling rate, remove C1 and replace C2 with two 0.02-pf, O-VCW, polystyrene-dielectric capacitors in series. CAUTION Since the two capacitors are in series, one will be off ground potential. Be sure to insulate the off- ground capacitor from the chassis. - Response time will th

42、en be about 50 msec. How- ever, ac rejection will be much less than with the standard filter. For example, a 60-cps signal with a peak value equal to full scale of the displayed range will cause readout variations as much as i200 counts. . The 405C can drive the 561B directly; the standard 561B cabl

43、e makes the necessary connections be- tween the voltmeter and recorder. However, the 405A-95C Digital Recorder Adapter is required to connect the 405C to the 560A. The adapter mates with the 100-pin output connector on the rear of the 405C and is held in place by two machine screws. The standard 560

44、A cable connects to the adauter. When connecting either recorder to the 405C, be sure both the recorder and 405A are turned o f f . CAUTION The405C chassis is connected to power-line ground through the adapterl550A system. Do not connect the voltmeter common lead to an off-ground potential while the

45、 560A is connected to the voltmeter. This caution also applies when using 405C with Models 561, 562 with dual input couplers. - 2-6 ELECTRICAL OUTPUT INFORMATION You can use the electrical information provided by the 405C for other purposes than operating a re- corder. For example, you might use the

46、 information to operate a remote readout identical to the one in the instrument or to record voltage information on punched cards or tape. Table 2-1 gives full details of the information available. 00518-2 Model 405C Pin TABLE 2-1. 53 OUTPUT CONNECTOR CHART Function Sect. II Page 3 Pin 1 2 3 4 5-11

47、12 13 14 15 16-25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41-43 44 45-46 47 48 49 50 Connector A (upper) Function 999-v range 99. 9-v range 1 9.99-v range 999-v range Decimal information; stepping switch stator; also see pin 44, J3A. No connection Jumpered to pin 38, J3A. +l2ov*lwo Polarity information: 0 volt on positive ranges, +110 volts on negative ranges; maximum external load 100K. Polarity information: +110 volts on positive