Elenco 23 Range 20k-V VOM in Kit Form User Manual
ANALOG MULTIMETER KIT
MODEL M-1250K
Copyright © 2007, 2000 by Elenco®Electronics, Inc. All rights reserved. Revised 2007 REV-H 753070
No part of this book shall be reproduced by any means; electronic, photocopying, or otherwise without written permission from the publisher.
Elenco®Electronics, Inc.
Assembly and Instruction Manual
PARTS LIST
If you are a student, and any parts are missing or damaged, please see instructor or bookstore.
If you purchased this kit from a distributor, catalog, etc., please contact Elenco
®
Electronics (address/phone/email is at the back of this manual) for additional assistance, if needed. DO NOT contact your place of purchase
as they will not be able to help you.
RESISTORS
Qty. Symbol Value Color Code Part #
1 R10 .04Ω Shunt Wire 100269
1R9 .97Ω 1% 1/2W black-white-violet-silver-brown 109731
1 R27 4.5Ω 1% 1/4W yellow-green-black-silver-brown 114530
1 R11 10Ω 1% 1/4W brown-black-black-gold-brown 121030
1 R22 18.5Ω 1% 1/4W brown-gray-green-gold-brown 121832
1 R12 102Ω 1% 1/4W brown-black-red-black-brown 131034
1 R21 200Ω 1% 1/4W red-black-black-black-brown 132030
1 R7 240Ω 1% 1/4W red-yellow-black-black-brown 132430
1 R20 2.08kΩ 1% 1/4W red-black-gray-brown-brown 142034
1 R13 3kΩ 1% 1/4W orange-black-black-brown-brown 143033
1R6 5kΩ 1% 1/4W green-black-black-brown-brown 145030
1 R31 5.6kΩ 1% 1/4W green-blue-black-brown-brown 145630
1 R32 8.2kΩ 1% 1/4W gray-red-black-brown-brown 148230
1 R25 18kΩ 1% 1/4W brown-gray-black-red-brown 151830
2 R35, R36 24kΩ 1% 1/4W red-yellow-black-red-brown 152430
1 R26 31kΩ 1% 1/4W orange-brown-black-red-brown 153130
1 R19 34kΩ 1% 1/4W orange-yellow-black-red-brown 153430
1 R5 40kΩ 1% 1/4W yellow-black-black-red-brown 154030
1 R23 44kΩ 1% 1/4W yellow-yellow-black-red-brown 154430
1 R17 83.3kΩ 1% 1/4W gray-orange-orange-red-brown 158330
1 R34 100kΩ 1% 1/4W brown-black-black-orange-brown 161030
1 R4 150kΩ 1% 1/4W brown-green-black-orange-brown 161533
1 R33 165kΩ 1% 1/4W brown-blue-green-orange-brown 161630
1 R18 195kΩ 1% 1/4W brown-white-green-orange-brown 161930
1 R30 260kΩ 1% 1/4W red-blue-black-orange-brown 162630
1 R16 360kΩ 1% 1/4W orange-blue-black-orange-brown 163630
1 R3 800kΩ 1% 1/4W gray-black-black-orange-brown 168030
1 R29 820kΩ 1% 1/4W gray-red-black-orange-brown 168230
1 R15 1.8MΩ 1% 1/2W brown-gray-black-yellow-brown 171831
1 R28 3MΩ 1% 1/2W orange-black-black-yellow-brown 173031
1R2 4MΩ 1% 1/2W yellow-black-black-yellow-brown 174031
1 R14 6.75MΩ 1% 1/2W blue-violet-green-yellow-brown 176731
1 R1 15MΩ 1% 1/2W brown-green-black-green-brown 181531
1 R24 10kΩ
Potentiometer 191508
1 R8 680Ω Potentiometer 191660
* NOTE: All fixed resistors are 1% tolerance (last stripe, brown). In some cases, resistors with a .5% tolerance
(last stripe, green) may be used in place of the 1% resistors.
CAPACITORS AND INDUCTORS
Qty. Symbol Value Marking Part #
1 C4 .001μF Discap (102) 231036
1 C3 .047μF Discap (473) 234710
1 C1 .047μF, 400V Mylar (473) 245028
1 L1 57.4mH Coil 455577
Note:
C2 is not used.
-1-
Caution: Do not mix alkaline, standard (carbon-zinc), or rechargeable (nickel-cadmium) batteries.
-2-
* These parts are part of the main rotary switch assembly. This may come preassembled by the factory.
SEMICONDUCTORS
Qty. Symbol Value Description Part #
2 D1, D2 2CZ Diode 314148
1 Q2 A1015 Transistor 321015
2 Q1, Q3 C1815 Transistor 321815
MISCELLANEOUS
Qty. Description Part #
1 PC Board 516001
1 Fuse 0.5A, 250V 533004
2 1.5V Battery 590001
1 9V Battery 590009
1Buzzer 595225
1 Selector Knob 622011
1 Zero Adjust Knob 622013
1 Case Bottom 623213
1 Top Cover Assembly 623116
1 Buzzer Case Top 623117
1 Buzzer Case Bottom 623214A
1 Selector Wiper 622014
1 Selector Base 622021
1 Screw M4 x 10 642309
2 Fuse Clip 663060
4 Input Sockets M-1250 664003
6 Transistor Socket M-1250 664004
1 Ball Bearing 666401
1 Selector Spring 680020
1 Battery Clip Double 680027
4 Battery Clip Single 680028
1 Wire 30AWG Stranded, 65mm (2.5”) Red 828202
1 Wire 30AWG Stranded, 65mm (2.5”) Yellow 828204
2 Wire 30AWG Stranded, 90mm (3.5”) Red 828220
1 Wire 30AWG Stranded, 90mm (3.5”) Green 828250
1 Wire 30AWG Stranded, 65mm (2.5”) Violet 828270
2 Wire 30AWG Stranded, 90mm (3.5”) White 828290
1 Wire 27AWG Bare 65mm (2.55”) or two 25.4mm (1”) wires 83J400
1 Lead-Free Solder Tube 9LF99
1 Test Lead Set 9TL11
*
*
*
*
*
Specifications
Measurement Ranges Accuracy Remarks
DC Voltage (DCV) All ranges ±3% FS Input impedance 20kΩ/V
1,000V ±5% FS
DCV Null Meter 0 - ±5V 0 - ±25V ±5% FS Zero centering meter type input impedance 40kΩ/V
DC Current 50μA - 2.5mA - 25mA - 250mA (50μA at the DC 0.1V position) ±3% FS Terminal Voltage drop: 250mV
10A ±5% FS 100mV . . . . 50μA
AC Voltage 0 - 10V - 50V - 250V ±4% FS Input impedance 9kΩ/V
1,000V ±5% FS
AF Output (dB) –10dB ~ +22dB (AC10V) ~ +62dB Input impedance 9kΩ/V for output terminal.
0dB/0.775V (1mW through 600Ω impedance circuit)
Resistance All ranges ±3% of arc Internal batteries: (2) 1.5V “AA”, (1) 9V
Buzzer Conduct indicator (buzzer is emitted at 20Ω or less.) Same Ω range, Power supply optional.
Battery Test (BATT) GOOD _? _BAD Color Coded Scale Load current 250mA
Leakage Current
0 - 150μA at X1k range 0 - 15mA at X10k range
Current across terminals.
(Iceo) (LI)
0 - 1.5mA at X100 range 0 - 15mA at X1 range
Terminal to Terminal Voltage (LV)
Common to each Ω range 3V - 0V (Reverse of LI scale) Voltage applied across terminal while Ω is measured.
DC Current Amplification Transistor h
FE
: 0 - 1000 Insert hFEterminal (on scale) directly.
Fact or ( h
FE
) (in x 10Ω range)
Size - 6 x 3 7/8 x 1 1/2 inches
Weight - 0.62 pounds
Introduction
Assembly of your M-1250 Analog Multimeter Kit will prove to be an exciting
project and give you much satisfaction and personal achievement. If you
have experience in soldering and wiring techniques, then you should have
no problem with the assembly of this kit. Care must be given to identifying
the proper components and in good soldering habits. Above all, take your
time and follow these easy step-by-step instructions. Remember, “An
ounce of prevention is worth a pound of cure”. Avoid making mistakes and
no problems will occur.
CAUTION: WEAR SAFETY GLASSES WHEN ASSEMBLING
THIS KIT.
Safety Procedures
• Wear eye protection when soldering and during all phases of this kit.
• Locate soldering iron in an area where you do not have to go around it
or reach over it.
• Do not hold solder in your mouth. Solder contains lead and is a toxic
substance. Wash your hands thoroughly after handling solder.
• Be sure that there is adequate ventilation present.
Assemble Components
In all of the following assembly steps, the components must be installed on
the top side of the PC board unless otherwise indicated. The top legend
shows where each component goes. The leads pass through the
corresponding holes and the board is turned to solder the component leads
on the foil side. Solder immediately unless the pad is adjacent to another
hole which will interfere with the placement of the other component. Cut
excessive leads with a diagonal cutter. Then, place a check mark in the box
provided next to each step to indicate that the step is completed. Be sure
to save the extra leads for use as jumper wires if needed.
Soldering
The most important factor in assembling your Analog Multimeter is good
soldering techniques. Using the proper soldering iron is of prime
importance. A small pencil type soldering iron of 25 - 40 watts is
recommended. The tip of the iron must be kept clean at all times and
well tinned. Many areas on the PC board are close together and care
must be given not to form solder shorts. Size and care of the tip will
eliminate problems.
For a good soldering job, the areas being soldered must be heated
sufficiently so that the solder flows freely. Apply the solder
simultaneously to the component lead and the component pad on the PC
board so that good solder flow will occur. Be sure that the lead extends
through the solder smoothly indicating a good solder joint. Use only
rosin core solder.
DO NOT USE ACID CORE SOLDER! Do not blob the solder over the
lead because this can result in a cold solder joint.
-3-
CONSTRUCTION
1. Solder all components from the
copper foil side only. Push the
soldering iron tip against both the
lead and the circuit board foil.
Component Lead
Soldering Iron
Circuit Board
Foil
Example 1
Poor solder connections occur when
the lead is not heated sufficiently. The
solder will not flow onto the lead as
shown. To correct, reheat the
connection and, if necessary, apply a
small amount of additional solder to
obtain a good connection.
Solder does not flow onto the lead. A hard
rosin bead surrounds and insulates the
connection.
Poor solder
connection
Soldering iron positioned incorrectly.
Example 2
A solder bridge occurs when solder
runs between circuit paths and creates
a short circuit. This is usually caused
by using too much solder. To correct
this, simply drag your soldering iron
across the solder bridge as shown.
4. Here is what a good solder
connection looks like. Cut off excess
leads.
Mount Part
Bend Leads to Hold Part
Solder & Cut Off Leads
Foil Side
Rx - 100Ω 5% 1/4W Resistor
(brown-black-brown-gold)
2. First apply a small amount of solder
to the iron tip. This allows the heat to
leave the iron and onto the foil.
Immediately apply solder to the
opposite side of the connection,
away from the iron. Allow the heated
component and the circuit foil to melt
the solder.
Solder
Soldering Iron
Foil
3. Allow the solder to flow around the
connection. Then, remove the
solder and the iron and let the
connection cool. The solder should
have flowed smoothly and not lump
around the wire lead.
Solder
Soldering Iron
Foil
IDENTIFYING RESISTOR VALUES
Use the following information as a guide in properly identifying the
value of resistors.
IDENTIFYING CAPACITOR VALUES
Capacitors will be identified by their capacitance value in pF
(picofarads), nF (nanofarads), or μF (microfarads). Most
capacitors will have their actual value printed on them. Some
capacitors may have their value printed in the following manner.
1 2 Multiplier
Tolerance
BANDS
Second Digit
First Digit
Multiplier
Tolerance
103K
100V
Maximum
Working Voltage
The value is 10 x 1,000 = 10,000pF or
.01μF 100V
The letter M indicates a tolerance of +20%
The letter K indicates a tolerance of +
10%
The letter J indicates a tolerance of +
5%
Note:
The letter “R” may be used at times
to signify a decimal point; as in 3R3 = 3.3
Multiplier
For the No. 0 1 2 3 4 5 8 9
Multiply By 1 10 100 1k 10k
100k
.01 0.1
-4-
ASSEMBLE COMPONENTS TO THE PC BOARD
After each step, put a check in the box located next to the step that you have completed.
Place the PC board on a table with the copper side facing up and insert the four input sockets into the PC
board holes as shown in Figure A. Solder the input sockets to the PC board as shown in Figure A. Apply
enough heat to allow the solder to flow around the input socket.
Insert the six transistor sockets into the PC board as shown in Figure 1 and then solder into place.
Figure B
Figure C
Figure D
Diodes have polarity.
Mount them with the
band as shown on the
top legend.
L1 - 57.4mH Coil
(see Figure B)
Q3 - C1815 Transistor
(see Figure C)
R34 - 100kΩ 1% 1/4W Resistor
(brown-black-black-orange-brown)
R33 - 165kΩ 1% 1/4W Resistor
(brown-blue-green-orange-brown)
R25 - 18kΩ 1% 1/4W Resistor
(brown-gray-black-red-brown)
R14 - 6.75MΩ 1% 1/2W Resistor
(blue-violet-green-yellow-brown)
R15 - 1.8MΩ 1% 1/2W Resistor
(brown-gray-black-yellow-brown)
R16 - 360kΩ 1% 1/4W Resistor
(orange-blue-black-orange-brown)
D2 - 2CZ Diode
(see Figure D)
R18 - 195kΩ 1% 1/4W Resistor
(brown-white-green-orange-brown)
R35 - 24kΩ 1% 1/4W Resistor
(red-yellow-black-red-brown)
R23 - 44kΩ 1% 1/4W Resistor
(yellow-yellow-black-red-brown)
R19 - 34kΩ 1% 1/4W Resistor
(orange-yellow-black-red-brown)
R20 - 2.08kΩ 1% 1/4W Resistor
(red-black-gray-brown-brown)
R36 - 24kΩ 1% 1/4W Resistor
(red-yellow-black-red-brown)
R17 - 83.3kΩ 1% 1/4W Resistor
(gray-orange-orange-red-brown)
R21 - 200Ω 1% 1/4W Resistor
(red-black-black-black-brown)
R31 - 5.6kΩ 1% 1/4W Resistor
(green-blue-black-brown-brown)
R32 - 8.2kΩ 1% 1/4W Resistor
(gray-red-black-brown-brown)
Flat
Side
0.1”
Band
Foil Side of PC Board
Solder
Solder
Figure A
Transistor SocketsInput Socket
Coil
Solder the coil to the foil
side of the PC board.
Foil Side
-5-
C3 - .047μF Discap (473)
R29 - 820kΩ 1% 1/4W Resistor
(gray-red-black-orange-brown)
Q1 - C1815 Transistor
(see Figure C)
R30 - 260kΩ 1% 1/4W Resistor
(red-blue-black-orange-brown)
R8 - 680Ω Potentiometer
(see Figure E)
R26 - 31kΩ 1% 1/4W Resistor
(orange-brown-black-red-brown)
R7 - 240Ω 1% 1/4W Resistor
(red-yellow-black-black-brown)
C1 - .047μF 400V (473) Mylar Cap.
(see Figure F)
R1 - 15MΩ 1% 1/2W Resistor
(brown-green-black-green-brown)
R2 - 4MΩ 1% 1/2W Resistor
(yellow-black-black-yellow-brown)
R3 - 800kΩ 1% 1/4W Resistor
(gray-black-black-orange-brown)
R4 - 150kΩ 1% 1/4W Resistor
(brown-green-black-orange-brown)
R5 - 40kΩ 1% 1/4W Resistor
(yellow-black-black-red-brown)
R11 - 10Ω 1% 1/4W Resistor
(brown-black-black-gold-brown)
R9 - .97Ω 1% 1/2W Resistor
(black-white-violet-silver-brown)
R12 - 102Ω 1% 1/4W Resistor
(brown-black-red-black-brown)
R6 - 5kΩ 1% 1/4W Resistor
(green-black-black-brown-brown)
R13 - 3kΩ 1% 1/4W Resistor
(orange-black-black-brown-brown)
Figure E
Mount the 680Ω pot to the PC board as
shown. Solder the leads to the foil side of the
PC board.
ASSEMBLE COMPONENTS TO THE PC BOARD
After each step, put a check in the box located next to the step that you have completed.
Figure F
Mount and bend the mylar capacitor as
shown. Solder and cut off the excess leads.
680Ω Po t
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