1、Model 187 all previously activated button features(HOLD, Hz, etc.) are discarded.The automatic power off is preset to 15 minutes. From theSetup menu (see Chapter 5), you can specify a maximumperiod of 23 hours, 59 minutes. If you set the period to 0,the meter remains on until you turn the rotary swi
2、tch toOFF or the batteries become too weak.Automatic power off does not occur if the meter is in MINMAX, FAST MN MX, AutoHOLD, or LOGGING(Model 189) mode.Getting AcquaintedBattery Considerations 22-3Automatic Backlight OffPress G84 to select the backlight level (low, high, or off.) Inlow or high, th
3、e backlight turns off automatically after agiven period. This period is also preset to 15 minutes andcan be set to a maximum of 99 minutes from the setupmenu. If the period is set to 0, the backlight is onindefinitely and can only be turned off by pressing G84 orturning the meter off.NoteSee Chapter
4、 5 for power off and backlight offsetup information.Low Battery IndicationA constant battery icon ( G66) in the upper left corner ofthe display notifies you that the batteries are low andshould be replaced.G87WarningTo avoid false readings, which could lead topossible electric shock or personal inju
5、ry,replace the batteries as soon as the batteryicon ( G66) appears.A flashing battery icon means that battery failure isimminent. The backlight cannot be used in this condition.MIN MAX and FAST MN MX features turn off. For Model189, logging and communications also cease.Model 187 refer to Chapter 4
6、for more information.The rotary switch is shown in Figure 2-2. Each position isdescribed in Table 2-1.dBdBac+dcac+dcac+dcac+dcFnSCLEAR MEMVmAAmVVmVOFFVIEW MEMCAAmAAtc012f.epsFigure 2-2. Rotary SwitchGetting AcquaintedPushbuttons 22-5PushbuttonsThe buttons activate features that augment the functions
7、elected with the rotary switch. The buttons are shown inFigure 2-3 and described in Table 2-2.Use the blue button ( G37) to access functions labeled inblue for some of the rotary switch positions. Table 2-1defines all blue button functions.Use the yellow button ( G79) followed by other buttonsto acc
8、ess additional features. These features appear inyellow above the appropriate keys. Table 2-2 definesyellow button features. This manual identifies the yellowbutton feature in parentheses following the buttonsequence . For example, activating the FAST MN MXmode appears as G79 G77 (FAST MN MX).MIN MA
9、XHOLD REL%msHz RANGEAutoHOLD LOGGINGSAVECANCELFAST MN MXSETUPYESNOtc013f.epsFigure 2-3. PushbuttonsThe following yellow button features are not available onModel 187: (YES), (NO), (LOGGING), and (SAVE).Model 187 the laststable reading is displayed.G77 Press to start retaining min, max, and average v
10、alues.Press successively to display max, min, and averagevalues. Press G79 G78 (CANCEL) to stop.FAST MN MXG79 G77Press to start FAST MN MX mode,where min and max values for shortduration events are stored.G68 Press to store the present reading as an offsetreference; subsequent readings show only the
11、 relativedifference from this value. Press again to show thedifference as a percentage of the reference.LOGGINGG79 G68Press to start and stop Logging(Model 189). Press G79 + G78(CANCEL) to stop.Getting AcquaintedPushbuttons 22-9Table 2-2. Pushbuttons (cont.)Button DescriptionYellow ButtonFunction De
12、scriptionG32G91 In Setup, increment a digit . In counter functions, select positive pulse slope. In ohms continuity, select beep on open. In VIEW MEM, see Chapter 4 (Model 189).(none)G93G32 In Setup, decrement a digit . In counter functions, select negative pulse slope. In ohms continuity, select be
13、ep on short. In VIEW MEM, see Chapter 4 (Model 189).(none)G82 Exit AUTO and enter MANUAL ranging. In MANUAL,select next input range. Press G79 G78(CANCEL) to return to AUTO.SAVEG79 G82Press to save present reading(Model 189)G78 Successively press for frequency, duty cycle, andpulse width.CANCELG79 G
14、78CANCEL any G37 (blue key) functionand all other button features.G37G115The blue button. Press to access blue functions onthe rotary switch. In Setup, use arrow function ( G115) toselect the next digit or item in a list.(none)Model 187 & 189Users Manual2-10Selecting the RangePress G82 to select eit
15、her a fixed range or theautorange feature.NoteYou cannot use G82 in conductance, diodetest, and temperature functions or with the REL,MIN MAX, and FAST MN MX features. Theseselections all use a specific fixed range.Autoranging (AUTO lighted in the display) always comeson initially when you select a
16、new function. In autorange,the meter selects the lowest input range possible,ensuring that the reading appears with the highestavailable precision (resolution).If AUTO is already on, press G82 to enter MANUALranging in the present range. You can then select the nextmanual range each time you press G
17、82. Return toautoranging by pressing G79 G78 (CANCEL).Understanding the DisplayDisplay features are shown in Figure 2-4 and described inTable 2-3. Major display features are described in thefollowing paragraphs.NoteYou can show all display segments (as shown inFigure 2-4) by pressing G81 while turni
18、ng themeter on. Release G81 to turn off the fulldisplay.Primary DisplayThe primary display usually shows the present reading forthe rotary switch function. For most of these functions, theprimary display can be set to show 4 or 5 digits. SeeChapter 5 for more information about display digits.Other u
19、ses for this display are: AutoHOLD: most recent held reading. MIN MAX: maximum, minimum, or average value.Getting AcquaintedUnderstanding the Display 22-11 dB (in ac volts functions): the dBm or dBV value. REL: the difference between the present reading anda stored reference reading. Setup: various
20、messages (see Chapter 5). Overload conditions: OL displayed. Error conditions.Secondary DisplayThe secondary display often shows the present readingwhen the primary display shows some other feature (MINMAX, REL , etc.)When multiple features are active, the secondary displayshows one of the values. F
21、or example, Hz could appear inthe secondary display while dB appears in the primarydisplay.Bar GraphThe bar graph provides an analog indication of themeasured input. For most measurement functions, the bargraph updates 40 times per second. Since this responseis much faster than the digital display,
22、the bar graph isuseful for making peak and null adjustments and forobserving rapidly changing inputs. The bar graph is notavailable in temperature, capacitance, ac over dc, dc overac, and ac+dc functions.Model 187 & 189Users Manual2-121416 151789101171356243112tc011f.epsFigure 2-4. Display FeaturesG
23、etting AcquaintedUnderstanding the Display 22-13Table 2-3. Display FeaturesNumber Feature DescriptionG4 G126 Continuity test function is selected.G5c60 c62Bar Graph.In normal operation 0 (zero) is on the left. In Relative %, 0 is in the center, negativevalues are to the left and positive to the righ
24、t.The polarity indicator left of the bar graph shows the polarity of the input. Both polarityindicators appear in REL% mode.The arrow right of the bar graph indicates an overload condition.Both arrows appear (without bar graph) when you can use G84 (G108) and G37 (G115) to selectsettings in the setu
25、p mode.G6 G112 Percent difference in Relative mode is being displayed in the primary display. Thereference value is shown in the secondary displayG7 G101 Relative (REL ) mode is active. The primary display has been modified by thereference value shown in the secondary display.G8-Indicates negative r
26、eadings. In Relative mode, this sign indicates that the present inputis less than the stored reference.G9 G90 30 V ac and/or dc may be present at the input terminals.G10 G66 Low battery. If flashing, battery failure is imminent, and logging and backlight aredisabled.G87WarningTo avoid false readings
27、, which could lead to possible electric shock or personalinjury, replace the battery as soon as the low battery indicator appears.Model 187 & 189Users Manual2-14Table 2-3. Display Features (cont.)Number Feature DescriptionG11FASTMINMAXAVGFAST MN MX mode is enabled. ( G79 G77)Minimum reading displaye
28、d.Maximum reading displayed.Average reading displayed.G12 G59 Readings are being recorded in memory (Model 189 only.) ( G79 + G68)G13 G103 The meter is in Hold mode. ( G81)G14 G103G83 AutoHOLD is active. ( G79 + G81)G15G56G46G56G46G56G46G56G46G56Primary Display (4-1/2 digit)G48G76Overload input.G16
29、Measurement UnitsV, mV V: Volts. The unit of voltage.mV: Millivolt. 1 x 10-3or 0.001 volts.dBm, dBV For ac volts functions, reading is shown in decibels of power above or below 1 mW(dBm) or decibels of voltage above or below 1 V (dBV).Getting AcquaintedUnderstanding the Display 22-15Table 2-3. Displ
30、ay Features (cont.)Number Feature DescriptionG16 AC+DC For dc volts and dc amps functions, reading represents the rms total of ac and dcmeasurements.G101, kG101 MG101, : Ohm. The unit of resistance.k: Kilohm. 1 x 103or 1000 ohms.M: Megohm. 1 x 106or 1,000,000 ohms.nS S: Siemens. The unit of conducta
31、nce.nS: Nanosiemens. 1 x 10-9 or 0.000000001 Siemens.nF, F, mF F: Farad. The unit of capacitance.nF: Nanofarad. 1 x 10-9 or 0.000000001 farads.F: Microfarad. 1 x 10-6or 0.000001 farads.mF: Millifarad. 1 X 10 -3or 0.001 farads.C ,F Degrees Celsius (default) or Fahrenheit.A, mA, A A: Amperes (amps). T
32、he unit of current.mA: Milliamp. 1 x 10-3or 0.001 amperes.A: Microamp. 1 x 10-6or 0.000001 amperes.Hz, kHz, MHz Hz: Hertz. The unit of frequency.kHz: Kilohertz. 1 x 103or 1000 hertz.MHz: Megahertz. 1 x 106or 1,000,000 hertz.Model 187 & 189Users Manual2-16Table 2-3. Display Features (cont.)Number Fea
33、ture DescriptionG1751000AUTOMANUALRange. Digits display range in use.G18G102MSG56G56G58G56G56Time Display. Used with HOLD, AutoHOLD, MIN MAX, FAST MN MX (SAVE, andLOGGING Model 189).Elapsed Time Display (G102 on): shown in minutes:seconds to maximum of 59:59 - used iftime since Min, Max, or Logging
34、started is less than 60 minutes. Always used for Min,Max, Avg. Displays hours:minutes after 1 hour.HMG56G56G58G56G5624-hour Display (G102 off): shown in hours:minutes to maximum of 23:59. For setting the24-hour clock, refer to Chapter 5.G19G56G46G56G46G56G46G56Secondary DisplayG20 MEMG113G49G56G56G5
35、6Memory Index Display (Model 189). Also used for dBm reference resistance.G113 appears when you can use G91 and G93 to increment or decrementsettings.G32Getting AcquaintedUsing the Input Terminals 22-17Using the Input TerminalsAll functions except current use the G42andCOMG32inputs. Current function
36、s use the inputs shownbelow: G73 or G75 function: Use A and COM inputs from 400mA to 20 A. Use mA/A and COM for inputs 400mA. G61 or G120 function: Use mA/A and COM for inputs 5000.0 A.If a test lead is plugged into the mA/A or A terminal, butthe rotary switch is not correctly set to one of the curr
37、entmeasuring positions, the Input Alert beeper warns youby making a chirping sound and the primary display shows“G76G69G65G100G53“. This warning is intended to stop you fromattempting to measure voltage, continuity, resistance,capacitance, or diode values when the leads are pluggedinto a current terminal.Figure 2-5 shows the input terminals.AmACOM VAtc014f.epsFigure 2-5. Input Terminals
