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15

charged.

e.

Connect the black test lead to the negative side of the circuit being measured
and the red test lead to the positive side of the circuit.

f.

Turn on power in circuit being measured.

g.

Read the voltage using the 0-10 figures on the black scale marked DC.
Multiply the reading by 100.

Turn off power to the circuit and wait until the meter indicates zero before discon-
necting the test leads.

4.9

AC Voltage Measurement 0-2.5 Through 0-500V

Range

Branch and distribution circuits (120/240/480V etc.) can deliver dangerous ex-
plosive power momentarily into a short circuit before the fuse/breaker opens the
circuit.  Make sure that the Instrument switches are set correctly, jacks are prop-
erly connected, and that the circuit power is turned off before making connections
to such circuits.

The 270 responds to the average value
of an AC waveform.  The Dial is cali-
brated in terms of the RMS value of a
pure sine wave.  If the waveform is non-
sinusoidal, and depending upon its
waveform, the reading may be either
higher or lower than the true RMS value
of the measured voltage.  Thus an error
may be introduced if the 270 is used to
measure a non-sinusoidal waveform.
Also, accuracy is lessened at higher in-
put frequencies (Figure 4-2).

Before proceeding with the following
steps, review the Safety Precautions in
Paragraph 4.1.

a.

Set the function switch at AC (Fig-
ure 4-3).

b.

Set the range switch at one of the
five voltage range positions marked
2.5V, 10V, 50V, 250V or 500V.
When in doubt as to actual voltage present, always use the highest voltage
range as a protection to the Instrument.  If the voltage is within a lower range,
the switch may be set for the lower range to obtain a more accurate reading.

c.

Plug the black test lead into the - COMMON jack and the red test lead into the
+ jack.

d.

Turn off power to the circuit to be measured and discharge any capacitors.

!

!

2.5V.

1V

-D.C.

+D.C.

10V.

50V

μ

AMPS

250V.
500V

1000V

COMMON

+1V.

+50 

μ

AMPS.

250MV.

1000V

AC.     D.C

ALL TERMINALS 1KV. MAX.

WARNING

READ MANUAL BEFORE USE

270

Figure 4-2. Frequency Response,
AC Voltage Ranges

Summary of Contents for 270-5

Page 1: ...Simpson 270 Series 5 Volt Ohm Milliammeter INSTRUCTION MANUAL ...

Page 2: ...factured by it to be free from defects in material and workmanship under normal use and service its obligation under this warranty being limited to making good at its factory or other article of equipment which shall within one 1 year after delivery of such instrument or other article of equipment to the original purchaser be returned intact to it or to one of its authorized service centers with t...

Page 3: ...oltage Measurement 0 250 Mv Range 13 4 6 DC Voltage Measurement 0 1V Range 13 4 7 DC Voltage Measurement 0 2 5 Through 0 500V Range 14 4 8 DC Voltage Measurement 0 1000v Range 14 4 9 AC Voltage Measurement 0 2 5 Through 0 500V Range 15 4 10 AC Voltage Measurement 0 1000V Range 16 4 11 Output Voltage Measurement 17 4 12 Decibel Measurement 20 to 50 dB 18 4 13 Direct Current Measurement 19 4 14 Dire...

Page 4: ...4 NOTES ...

Page 5: ... the Instrument when the Instrument is misused The fuse varistor combina tion in the 270 has been designed to afford maximum instrument protection un der foreseeable overload conditions which might occur within the measuring capabilities of the Instrument However the operator must use care to avoid severe overloads particularly when working in high voltage circuits a Fuses Basic overload protectio...

Page 6: ...oping position for easy viewing The case can also be placed either vertically or horizontally The horizontal position is preferable for greater accuracy since the Instrument is calibrated in this position 1 7 Test Leads Each Instrument is furnished with one pair Catalog Number 00043 of probe type test leads one red and one black each 48 inches long for all applications of the Instrument These test...

Page 7: ... c r A f o 5 2 1 c r A f o 1 0 0 0 0 1 x R 10 DECIBELS Ranges 20 to 10 dB 8 22dB 6 to 36 dB 20 to 50 dB Reference Level W zero power level equal to 1 mW across a 600 line 11 BATTERIES 1 5V D Size NEDA 13F 9V NEDA 1604 12 FUSES F1 1A 250V type 3AG quick acting Littlefuse Type 312001 F2 2A 600V Bussman Type BBS or Littlefuse Type BLS 13 TEST LEADS 1 red 1 black 48 long 14 SIZE 5 1 2 x 7 x 3 1 8 13 3...

Page 8: ...pecial caution and warning symbols which alert the user to hazardous operating and servicing conditions These symbols appear throughout this publication where applicable and are defined on the inside front cover of this manual under NOTES AND SAFETY INFORMATION These instructions must be adhered to in order to ensure the safety of operating and servicing personnel and to retain the operating condi...

Page 9: ...tions on how to open the battery compartment and install the batteries 2 2 Warranty The Simpson Electric Company warranty policy is printed on the inside front cover of this manual Read the warranty policy carefully before requesting any warranty repairs For all assistance including help with the Instrument under warranty contact the nearest Authorized Service Center for instructions If nec essary...

Page 10: ...e rotated in either direction to select the desired voltage current or resistance range position 3 Function Switch The function switch has four positions Off Transit DC DC and AC To measure DC current or voltage set the function switch at the DC or DC position de pending on polarity of the signal applied across test leads To measure AC voltage set the function switch to the AC position For resista...

Page 11: ...ronmental conditions 4 OPERATION This section contains information required to operate the 270 5 safely and prop erly Multifunction Instruments VOM s such as the 270 5 are intended as general purpose measuring instruments for use in low power circuitry such as found in consumer appliances TV and radio receivers and in general laboratory applica tions Their use is not recommended in high voltage hi...

Page 12: ...fore making con nections to circuitry Voltage may appear unexpectedly or in unexpected locations in faulty equipment An open bleeder resistor for example may result in a capacitor retaining a dangerous charge k Make certain that the equipment being worked on is properly grounded and fuses are of the proper type and rating l Double check switch positions and jack connections before applying power t...

Page 13: ... DC Voltage Measurement 0 250 mV Range NOTE For polarity reversing see paragraph 4 2 Before measuring voltage review the SAFETY PRECAUTIONS listed in para graph 4 1 Also when using the 270 as a millivoltmeter care must be taken to prevent damage to the indicating instrument from excessive voltage Before using the 250 millivolt range use the 1 0 volt DC range to determine that the voltage measured ...

Page 14: ...e black scale marked DC For the 2 5V range use the 0 250 figures and divide by 100 For the 10V 50V and 250V ranges read the figures directly For the 500V range use the 0 50 figures and multiply by 10 Turn off power to the circuit and wait until the meter indicates zero before discon necting the test leads 4 8 DC Voltage Measurement 0 1000V Range Use extreme care when working with high voltage circ...

Page 15: ...the waveform is non sinusoidal and depending upon its waveform the reading may be either higher or lower than the true RMS value of the measured voltage Thus an error may be introduced if the 270 is used to measure a non sinusoidal waveform Also accuracy is lessened at higher in put frequencies Figure 4 2 Before proceeding with the following steps review the Safety Precautions in Paragraph 4 1 a S...

Page 16: ... any circuit to ground voltage measurement which may exceed 1000 volts Be sure that the range switch is set to the 500V 1000V range function switch to AC position and test leads connected to common and 1000V jack Do not touch the Instrument or test leads while the power is on in the circuit being measured a Set the function switch at AC Figure 4 3 b Set the range switch at 500 1000V position c Plu...

Page 17: ...ircuit The blocking capacitor may alter the AC response at low frequencies but is usually ignored at audio frequencies Figure 4 4 Do not connect the OUTPUT jack to a circuit in which the DC voltage component exceeds 350V Before proceeding with the following steps review the Safety Precautions in Paragraph 4 1 a Set the function switch at AC Figure 4 5 b Plug the black test lead into the COMMON jac...

Page 18: ... 2 5V range zero dB 0 775V Higher ranges may be used by adding an appropriate dB value to the reading in accor dance with chart on the following page a Review the safety precautions in paragraph 4 1 b Set the functions switch at AC figure 4 6 c Plug the black test lead into the COMMON jack and the red test lead into the jack c Use operating instructions for AC VOLTAGE MEASUREMENT 0 2 5 10 50 250 5...

Page 19: ...lead into the COMMON jack and the red test lead into the 50μA 250mV jack c Set the range switch at 50μA dual position with 50V d Turn OFF power Then discharge any capacitors in the circuit e Open the ground side of the circuit in which the current is being measured Connect the VOM in series with the circuit Connect the red test lead to the positive side and the black test lead to the negative side...

Page 20: ...azardous to the operator Turn off circuit power and wait for the meter reading to drop to zero The polarity reversing feature of the function switch does not operate on the 0 10A range If polarity is found to be incorrect turn off circuit power wait for the meter indication to read zero and then interchange test lead connections to the circuit a Plug the black test lead into the 10A jack and the r...

Page 21: ...g connections to it When making in circuit measurements circuit paths in parallel with the resis tance being measured may cause reading errors Check circuit diagrams for the presence of such components before assuming that the reading obtained is correct a Before measuring resistance in the circuit make sure the power is off in the circuit being tested and all capaci tors discharged b Disconnect t...

Page 22: ...cuit forward and reverse bias resis tance measurements consider the following before making the measurement a The polarity of the internal ohmmeter battery voltage at the positive jack is identical to the function switch polarity setting and opposite to the com mon jack Make sure that the OHMS range being used will not damage any of the semiconductors refer to Table 1 1 item 8 Section 1 b If the s...

Page 23: ... fastened in place before the Instrument is used Do not permit an Instrument with a broken glass meter cover to be used Whenever the battery compartment cover is removed for any reason check that the proper fuses are being used Severe overloads may have damaged the Instrument s circuitry despite the pro tection afforded by the fuse When a fuse is replaced all ranges should be routinely checked cal...

Page 24: ...ttery and fuse compartment Access compartment by de energizing and disconnecting the test leads and loosening the single captivated screw on the compartment cover To replace or check a fuse apply pressure to the 1 amp fuse cup then rotate the plate to expose a selected fuse for removal from the panel s cavity Replace the 1 and 2 ampere fuse with the specified fuse type only See replace ment parts ...

Page 25: ...0 days check the batteries for leakage and replace if neces sary e It is recommended that the Instrument be returned annually to the nearest Authorized Service Center or to the factory for an overall check adjustment and calibration f When not in use store the Instrument in an environment free from tempera ture extremes dust corrosive fumes and mechanical vibration or shock If storage time is expe...

Page 26: ...26 NOTES ...

Page 27: ...27 NOTES ...

Page 28: ...SIMPSON ELECTRIC COMPANY 520 Simpson Avenue Lac du Flambeau WI 54538 0099 715 588 3311 FAX 715 588 3326 Printed in U S A Part No 06 111642 Edition 15 07 17 Visit us on the web at www simpsonelectric com ...

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