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Summary of Contents for WV-38A

Page 1: ...SUGGESTED PRICE 5Q CENTS operating and maintenance instructions ...

Page 2: ...which can provide a ground Working with one hand in your pocket and stand ing on a properly insulated floor lessens the danger of shock 2 Filter capacitors may store a charge large enough to be lethal Therefore discharge filter capacitors before attaching test leads 3 Remember that leads with broken insulation provide the addi tional hazard of high voltages appearing at exposed points along the le...

Page 3: ...ny types of semi conductor devices Two special silicon diodes are used to protect the meter movement against burnout due to accidental overload A fuse protects the precision multiplier in the ohms network The WV 38A is completely portable requiring no external power source Five internal batteries not provided are used for the ohms function 4 penlight cells and 1 D size flashlight cell The unit wei...

Page 4: ... milliampere o M o 1 0 to 10 milliamperes K a n g e s 0 to 100 milliamperes 0 to 500 milliamperes 0 to 10 amperes Insertion Loss 0 25 volt Accuracy 3 DC Ohms Ranges Scale Ends Center Scale Full Scale Currents R X 1 0 2000 12 ohms 120 M A R X 1 0 0 0 200 000 1200 ohms M A R X 10 000 0 20 000 000 120 000 ohms 0 06 M A Accuracy 3 of pointer position for exact value Internal Batteries R X 1 SizeD Cell...

Page 5: ...scale for convenience is used when making decibel measurements The Range Switch located at the center of the control panel has 12 positions The Range Switch may be turned in either direction to obtain the function and range desired The Function Switch located at the upper left hand corner of the panel has three positions AC DC and DC To measure all A C Voltages and to make decibel measurements the...

Page 6: ...ge only should be used if a reading of best accuracy is to be obtained This general rule applies to all A C and D C Voltage ranges For resistance measurements however the range selected should be the one which provides a reading nearest the center of the scale because the WV 38A provides the most accurate Ohms readings at mid scale points For some measurements it will be necessary to use a multipl...

Page 7: ...d Note In rare applications where high energy rf is present such as measur ing dc keep alive voltage on TR tubes in radar equipment it may be necessary to disconnect meter protection diodes CR3 and CR4 Special 25 Volt 1 Volt and 5000 Volt Ranges Note When using the 25 V and 1 V jacks the Function Switch must be set to the D C position Meter polarity must be observed by applying the red test lead t...

Page 8: ...e C O M M O N jack on the control panel 4 Plug the red test lead into the jack on the control panel when the 2 5 V 10 V 50 V 250 V or 1000 V range is used When the 5000 V range is used the red test lead must be plugged into the A C 5 K V jack 5 Connect the test leads to the voltage source to be measured 6 Reset the Range Switch to a position which gives a suitable pointer deflection 7 Read the A C...

Page 9: ...position which gives a suitable pointer deflection 7 Read the D C current from the scale corresponding to the range selected 8 To use the 50 iA range set the Range Switch to the 50aA position and the Function Switch to DC Plug the red test lead into the 4 25 V 50 A jack Meter polarity must be observed by applying the red test lead to the most positive current connection and the black lead to the n...

Page 10: ...Range Switch if necessary to a position which gives a suit able pointer deflection If this is necessary repeat steps 5 and 6 before proceeding with step 8 8 Read the resistance from the O H M S scale and multiply by the range factor C A U T I O N Low current low resistance devices such as thermo couples and meter movements may be damaged unless a range above R X I is used because the WV 38A applie...

Page 11: ...4 Plug the red test lead into the O U T P U T jack on the control panel 5 Connect the test leads to the A C source to be measured 6 Reset the Range Switch to a position which gives a suitable pointer deflection 7 Read the decibel measurement directly from the D B scale when using the 2 5 V range When using the 10 V 50 V or 250 V range refer to the chart located at the lower right hand corner of th...

Page 12: ...100 times I E 25 000 V DC These probes and multiplier combinations make possible measurements in T V high voltage power supplies and other high impedance circuits having inherently poor regulation Applications The WV 38A is designed to measure the significant characteristics of electrical and electronic circuits It will measure the voltage the current and the resistance of all D C circuits For A C...

Page 13: ...t be in the D C position Checking Rectifiers The resistance of copper oxide selenium silicon and crystal recti fiers can be measured in both directions The resistance measured should be quite large in one direction and very small in the opposite direction The front to back resistance ratio can be checked easily by setting the Function Switch from D C to DC thus reversing the polarity of the test l...

Page 14: ...A C voltage ranges as with the D C voltage section are ob tained by using a voltage divider network The resistors in this network are RIO R l l R12 R13 R14 and R28 R24 is a 6K potentiometer for cali brating the low A C ranges R23 also a 6K potentiometer is for calibrating the high A C ranges DC Current The D C current ranges are obtained by switching the appropriate values of shunt resistance acro...

Page 15: ...nd serves to protect the resistors used for ohms measurement against damage due to accidental overload Maintenance The WV 38A may be removed from its case simply by removing four screws from the rear of the case The meter panel laminated circuit board and batteries are removed as a complete unit The need for battery replacement is indicated when the instrument will not zero properly on the Ohms ra...

Page 16: ...ead clipped from the defective fuse Care should be taken to prevent any short circuit and if necessary a piece of insulating sleeving may be placed over the fuse to prevent a short circuit N O T E A burned out fuse will make the instrument inoperative dn all functions in which the 4 4 C O M M O N jack is used DC Calibration If an accurate D C Current source is available it is recommended that the ...

Page 17: ...tes full scale 9 Remove the test leads from the 2 5 V A C source Removing the Laminated Circuit Board When it is necessary to gain access to the under side of the laminated circuit board or to the parts located between it and the front panel the laminated circuit board must be removed To remove the laminated circuit board proceed as follows 1 Set the Range Switch to the 2 5 V position 2 Remove the...

Page 18: ...1 M F D 400V Symbol No Description Stock No Rl R2 R3 R 4 R5 R6 R7 R8 R9 R10 R l l R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 M l CR1 CR2 CR3 CR4 F l Bl B2 SI S2 Rectifier Crystal Diode Type IN87 230099 Crystal Diode 230125 Fuse Fuse Pigtail 3AG 1 A M P 250V 212492 Batteries Type D 1 5V VS 036 Type A 1 5V VS 034 Switches Range Switch 218877 Function Switch 218876 Miscel...

Page 19: ... A 8 1 0 M A 1 0 A 9 1 M A 1 0 R X 1 1 1 R X100 1 2 R X 1 0 0 0 0 25V 50JJA DCQ OUTPUT o AC5KV O DC 5KV o ct 1 MFD R28 20 MEG 2W O R29 SO MEG 2W tOOOVAC CR3 M1 50 jJA CR4 H 4 R22 6K CAL 2 ALL SWITCH WAFERS SHOWN AS VIEWED FROM FRONT SHAFT END OF SWITCH 3 S1 SHOWN IN POSITION 1 4 S2 SHOWN INW DCH POSITION 5 SWITCH CONTACTS SHORT ARROWS INDICATE WIPER CONNECTION LONG ARROWS INDICATE CENTER RING CONN...

Page 20: ...ItC 1 Printed in U S A ...

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