1、DIGITAL MULTIMETER KITMODEL M-2666KWIDE RANGE DIGITAL MULTIMETER WITHCAPACITANCE AND TRANSISTOR TESTING FEATURESAssembly and Instruction ManualNo part of this book shall be reproduced by any means; electronic, photocopying, or otherwise without written permission from the publisher.-1-INTRODUCTIONRa
2、ngeSwitchesCurrentShuntsACConverterOhmsConverterVoltageDividerFunctionSwitchesA/DConverterandDisplayDriverDisplayDecimalPointDCAnalogDataVVACVAC/mA ACmAmAmACOMMV/VFigure 1 Simplified Block DiagramTHEORY OF OPERATIONA block diagram of the M-2666K is shown in Figure 1.Operation centers around a custom
3、 LSI chip. This ICcontains a dual slope A/D converter, display, latches,decoder and the display driver. A block diagram ofthe IC functions is shown in Figure 6. The inputvoltage, current or ohm signals are conditioned by thefunction and selector switches to produce and outputDC voltage between 0 and
4、 +199mV. If the inputsignal is 100VDC, it is reduced to 100mV DC byselecting a 1000:1 divider. Should the input be100VAC, then after the divider it is processed by theAC converter to produce 100mVDC. If current is to beread, it is converted to a DC voltage via internal shuntresistors. For resistance
5、 measurements, an internalvoltage source supplies the necessary 0-199mVvoltage to be fed to the IC input.The input of the 7106 IC is fed to an A/D (analog todigital) converter. Here the DC voltage amplitude ischanged into a digital format. The resulting signalsare processed in the decoders to light
6、the appropriateLCD segment.Timing for the overall operation of the A/D converteris derived from an external oscillator whosefrequency is selected to be 40kHz. In the IC, thisfrequency is divided by four before it clocks thedecade counters. It is further divided to form thethree convert-cycle phases.
7、 The final readout isclocked at about three readings per second.Digitized measurements data is presented to thedisplay as four decoded digits (seven segments) pluspolarity. Decimal point position on the display isdetermined by the selector switch setting.Assembly of your M-2666 Digital Multimeter Ki
8、t willprove to be an exciting project and give muchsatisfaction and personal achievement. If you haveexperience in soldering and wiring technique, youshould have no problems. For the beginner, caremust be given to identifying the proper componentsand in good soldering habits. Above all, take yourtim
9、e and follow the easy step-by-step instructions.Remember, “An ounce of prevention is worth apound of cure”.The meter kit has been divided into a number ofsections to make the assembly easy and avoidmajor problems with the meter operation.Section A - Meter display circuit assembly.Section B - DC volt
10、age and current circuitassembly.Section C - AC voltage and current circuitassembly.Section D - Resistance as in 3R3 = 3.310F 16V103K100VThe letter M indicates a tolerance of +20%The letter K indicates a tolerance of +10%The letter J indicates a tolerance of +5%Maximum Working VoltageThe value is 10
11、x 1,000 =10,000pF or .01F 100V*-9-RESISTOR READING EXERCISE(1) yellow-black-black-black-brown(3) brown-red-violet-red-brown(5) brown-black-black-black-brown(7) white-black-black-yellow-green(9) brown-black-black-orange-green(11) gray-white-black-black-brown(2) white-black-black-red-green(4) green-bl
12、ack-green-brown-green(6) brown-green-gray-orange-brown(8) white-black-black-silver-green(10) orange-white-red-red-brown(12) brown-brown-black-red-brownAns wer s to Resistor Reading Ex er cise:1) 400 + 1%;2) 90k + .5%;3) 12.7k + 1%;4) 5.05k + .5%;5) 100 + 1%;6) 158k + 1%;7) 9M + .5%;8) 9 + .5%;9) 100
13、k + .5%;10) 39.2k + 1%;11) 890 + 1%;12) 11k + 1%;Before starting assembly of your digital multimeterproject, you should be thoroughly familiar with the 5band color code system. Many of the resistorvalues will be identified by color bands and it is easyto mistake their value if you read the colorsinc
14、orrectly or read the value from the wrong end.Do the following exercise in resistor values. Placeyour answer in the box beneath the resistor.Answers are on the bottom of this page.-10-PARTS LIST - SECTION AIf you are a student, and any parts are missing or damaged, please see instructor or bookstore
15、.If you purchased this kit from a distributor, catalog, etc., please contact ElencoTMElectronics (address/phone/e-mail is at the back of this manual) for additional assistance, if needed. DO NOT contact your place of purchaseas they will not be able to help you.RESISTORSQty. Symbol Description Color
16、 Code Part #2 R4, R5 100k 5% 1/4W brown-black-yellow-gold 1610001 R3 200k 5% 1/4W red-black-yellow-gold 1620001 R1 220k 5% 1/4W red-red-yellow-gold 1622003 R7, R8, R9 470k 5% 1/4W yellow-violet-yellow-gold 1647002 R2, R6 1M 5% 1/4W brown-black-green-gold 171000CAPACITORSQty. Symbol Value Description
17、 Part #1 C5 100pF (101) Disc 2210171C1 .1F (104) Mylar (large brown) 251017L3 C2, C3, C4 .1F (104) Mylar (small yellow) 251017S1C6 2F Electrolytic (Lytic) 272244SSEMICONDUCTORSQty. Symbol Value Description Part #1 T1 9013 Transistor 2SC9013 329013MISCELLANEOUSSECTION AMeter Display CircuitResistorPA
18、RTS IDENTIFICATIONDiode PC Board Liquid Crystal Display (LCD)Qty. Description Part #1 LCD 3511661 Zebra 5000071 PC Board M2666K 5126661 Switch On/Off (SW1) 5400041 Battery 9V 590009Qty. Description Part #1 Battery Snap (Batt) 5900981 LCD Housing 6290151 LCD Cover 6290161 Label Top 7230511 Solder 9ST
19、4ATransistorLabel TopDisplayHousingDisplayCoverZebraLCDCapacitorsDisc LyticMylarC1-11-ASSEMBLE THE FOLLOWING COMPONENTS TO THE PC BOARDIn all of the following steps the components must be installed either on the top or bottom legend sides ofthe PC board as indicated. The board is turned to solder th
20、e component leads on the opposite side(installed on Bottom, soldered on Top, installed on Top, soldered on Bottom).Figure D Lay resistor flat against thePC board.R8 - 470k 5% 1/4W Res.(yellow-violet-yellow-gold)(see Figure A)C6 - 22F Lytic Capacitor(see Figure B)R4 - 100k 5% 1/4W Res.(brown-black-ye
21、llow-gold)(see Figure A)C5 - 100pF (101) DiscapR3 - 200k 5% 1/4W Res.(red-black-yellow-gold)(see Figure A)C4 - .1F (104) Mylar Cap.(small yellow)C3 - .1F (104) Mylar Cap.(small yellow)R2 - 1M 5% 1/4W Res.(brown-black-green-gold)(see Figure A)Figure AStand resistor on end asshown. Solder and cut offt
22、he excess leads.White markingon PC boardFigure BMount the capacitor with the negative ()lead in the negative hole and the positive(+) lead in the positive hole marked on thePC board. Mount the capacitor flatagainst the PC board as shown.Figure CMount the transistorwith the flat side in thesame direc
23、tion as thePC board marking.Markingon PC boardFlatSideNegative ()marking onPC boardNegative ()marking oncapacitorR7 - 470k 5% 1/4W Res.(yellow-violet-yellow-gold)(see Figure A)T1 - 2SC9013 Transistor(see Figure C)R5 - 100k 5% 1/4W Res.(brown-black-yellow-gold)(see Figure D)R6 - 1M 5% 1/4W Res.(brown
24、-black-green-gold)(see Figure A)R9 - 470k 5% 1/4W Res.(yellow-violet-yellow-gold)(see Figure A)C1 - .1F (104) Mylar Cap.(large brown)R1 - 220k 5% 1/4W Res.(red-red-yellow-gold)(see Figure A)C2 - .1F (104) Mylar Cap.(small yellow)Figure EInsert the switch into thePC board in the locationshown. Make s
25、ure thatthe notch on the switchis in the same directionas the marking on thePC board.Insert the 9V batterywires through the hole ofthe PC board as shown.Solder and cut off theexcess leads.Black WireRed WireTop Legend SideBottom Legend SideMount switch in direction shown.NotchSW1 - Switch On/Off(see
26、Figure E)BATT - 9V Battery Snap(see Figure E)Assembled ViewAssemble the LCD into the housing with the partsshown in Figure F. Note the top of the house iscurved.Wipe off zebra edges with a lint-free cloth andthen insert the zebra into the top slot of thehousing.The LCD must be put in with the notch
27、in thedirection shown in Figure F. Peel off the clearprotective film on top of the LCD (see Figure F),then place the LCD into the housing.Place the display cover on top of the housing andpress down to snap into place.Place the LCD housing on top of the PC board asshown.Testing ProcedureThe LCD housi
28、ng will not be screwed to the PCboard for this test. Align the LCD housing holes withthose in the PC Board and hold in place. You canalso use a rubber band to hold the housing. You willneed to apply pressure so the zebra makes contactto the copper pads.1. Place the top label over the knob. This will
29、 assistin obtaining the correct knob position.2. Connect the 9V battery to the battery snap3. Turn the meter on by pressing the power switch(down position).4. Align the LCD housing holes with those in the PCBoard and hold in place. You can also use arubber band to hold the housing. You will need toa
30、pply pressure so the zebra makes contact to thecopper pads.5. Set the selector switch to the 200 position. Thefirst decimal point should light and show a 200under it. Select the 20k position and thesecond decimal points lights with a 20 under it.Select the 2k position and the second decimalpoints li
31、ghts with a 2 under it. Adjust the selectorto other ranges and check that correct decimalpoint lights. The LCD will display randomnumbers.If the tests are not working, check for cold solderjoints, part values and if the LCD is assembledcorrectly. DO NOT PROCEED TO SECTION BWITHOUT INSTRUCTORS APPROV
32、AL.-12-ASSEMBLE THE LCDFigure GClear Protective FilmTapeLCD CoverLCDNotchZebraPC BoardBatteryRange SelectorKnob AssemblyDo not touch edgeFigure FLCD Housing-13-PARTS LIST - SECTION BRESISTORSQty. Symbol Description Color Code Part #1 R23 .01 Shunt wire 1001661 R22 0.99 0.5% 1/4W black-white-white-si
33、lver-green 1099501 R21 9 0.5% 1/4W white-black-black-silver-green 1190501 R20 90 0.5% 1/4W white-black-black-gold-green 1290501 R18 100 0.5% 1/4W brown-black-black-black-green 1310501 R32 390 1% 1/4W orange-white-black-black-brown 1339301 R31 900 1% 1/4W white-black-black-black-brown 1390302 R17, R1
34、9 900 0.5% 1/4W white-black-black-black-green 1390501 R33 5.6k 5% 1/4W green-blue-red-gold 1456001 R16 9k 0.5% 1/4W white-black-black-brown-green 1490501 R30 13k 1% 1/4W brown-orange-black-red-brown 1513301 R15 90k 0.5% 1/4W white-black-black-red-green 1590501 R14 900k 0.5% 1/4W white-black-black-or
35、ange-green 1690504 R10-R13 2.25M 0.5% 1/4W red-red-green-yellow-green 1722501 VR1 200 (201) Pot (lay down) 191320Note: Resistor tolerance (last band) of 5-band resistors may be blue instead of green.SEMICONDUCTORSQty. Symbol Value Description Part #2 D1, D2 1N4001 Diode 3140011 T2 2SA9013 9013 32901
36、3MISCELLANEOUSQty. Symbol Description Part #1 Fuse 0.2A 250V 5 x 20mm 5300202 Screw 2.5 x 8mm 6422392 Fuse Clips 6630044 Input Socket (10A, A/mA, COM, VCAP) 664066SECTION BDC Voltage therange will also be 20 to 550. If the tests are notworking, check components R49 R50, and thetransistor sockets.5.
37、Turn the meter off and remove the battery, toplabel, and test leads.DO NOT PROCEED TO SECTION F WITHOUT INSTRUCTORS APPROVAL.Attach the LCD to the PC board using the two 2.5x 8mm screws. Use the top-mounting hole andlightly tighten the screws.Assembled View for Section BAssembled Views for Section E
38、-22-Solder the spring to the PC board as shown inFigure Q.Install the bottom two 2.5 x 8mm screws to theLCD housing as shown in Figure R.Peel off the protective backing on the top label(A) and bottom label (B) and stick them to the topcase as shown in Figure S.Place the PC board into the bottom case
39、. Feedthe battery clip through the case as shown inFigure T.Place the four colored sleeves over the inputsockets as shown in Figure T. Note that the blacksleeve goes on the COM socket.Place the red power cap onto the switch SW1 asshown in Figure T.Figure R2.5 x 8mm ScrewsFigure STop Label (A)Bottom
40、Label (B)FINAL ASSEMBLYPARTS LIST - SECTION FSECTION FFinal AssemblyQty. Description Part #1 Button (red) 6220273 Sleeve Input Socket (yellow) 6226601 Sleeve Input Socket (red) 6226611 Case Top 6231121 Case Bottom 6232031 Cover Battery 6232102 Screw LCD Housing 2.5 x 8mm 642239Qty. Description Part
41、#2 Screw Case 3 x 17.5mm 6422401 Spring 6800331 Label Bottom 7230521 Shield Label 7800121 Holster 9C721 Test Leads Alligator 9TL131 Test Leads Red-Black 9TL14Note: The shield may be installed already.Figure QSolderSpring-23-Top CaseInput SocketSleevesRed Power CapPC BoardBottom CaseShield LabelFigur
42、e TBlackFeed thebattery snapthrough thisopening.Battery Snap-24-Testing Procedure SECTION C - AC voltageand current circuit1. Set range selector knob to an AC Volt scaleposition.2. Connect the test leads (red lead to VCAP andblack to COM). Turn the meter on by pressing thepower switch.3. Measure an
43、AC voltage with a known accuratemeter. Now measure the voltage with the kitmeter. The meters should be the same voltage.Current Test1. Turn the range selector knob to the 200Aposition.2. Connect the test leads (red lead to A/mA andblack to COM).Connect the kit meter and another meter of knownaccurac
44、y in series. Set the meters in the 200Aposition. Construct a circuit for an AC current andmeasure the circuit current. Both meters shouldhave close to the same readings. If the meters donot agree, check the parts just added. Do not re-adjust VR1 this will change the voltage reading setin step 1. Che
45、ck the 2m - 200mA scales. The 20Ascale requires a circuit of 1 - 20 amps. If the testsare not working, check for cold solder joints and partvaluesFeed the battery snap wires through the slot onthe top case as shown in Figure U.Connect the battery and place it in the cavity ofthe top case as shown in
46、 Figure V.Place the battery cover onto the case as shownin Figure V. Hold the two sections together withtwo M3 x 17.5 screws.FINAL ASSEMBLY (continued)Figure VM3 x 17.5 ScrewsBattery CoverBatteryFigure UBattery Snap Wires Slot-25-U1 (7106) Voltage Test1. Measure the voltage across pin 8 and pin 34 o
47、nU1 (7106) for 9V.A. Check the battery and SW1 connections.B. Check for a 9V and GND short.1. One of the ICs may be bad. Removeone IC at a time and check voltageagain between pins 8 and 34.2. Measure the voltage from pin 8 to COM on U1 for3V.A. U1 is defective.3. Check the Main Oscillator on U1 (710
48、6) pins 6, 7,and 4.Pin 6Pin 7Pin 44. Measure the voltage from pin 44 to COM on U1(7106) = 0.1V.A. Adjust VR1 so the the junction of R31,R33 and VR1 equal to 100mV.1. Cant set to 100mV.a. VR1 wrong value or defective.b. R30 - R32 wrong value.Voltage/OHM Section1. Measure across VCAP terminal and COMt
49、erminal for 10M (set meter in 200mV) batteryinstalled.A. Lower or higher than 10M.1. Check resistors R10 - R18.2. LCD readings floating.A. Measure from COM terminal to pin 43 onU1 (7106) for 220k.1. R3 open or defective.AC Voltage Section1. Apply 15VAC to meter and measure pin 14 of U2(324) to COM terminal with a scope (meter on20VAC scale).Pin 14 to COM 2VppA. Check IC2 and R342. Check junction R39 and C11 of U1 (7106) with ascope.Waveform for junction R39 and C11.A. Check R35 - R39, C7 - C11, D3 - D5,
