Elenco 3 1/2 Digit Cap. / Trans. Kit - Manual (Page 27)

Amps Section
1.
μ
A/mA scale not working:
A. Check fuse.
B. Measure across (
μ
A/mA) terminal and
(COM) terminal and check the following
settings:
200
μ
= 1k
Ω
2m = 100
Ω
20m = 10
Ω
200m = 1
Ω
1. Lower or higher check R19 - R23.
2. 10A scale not working:
A. Check shunt.
Capacitance Section
1. Connect the .1
μ
F cap to the meter and check pin
14 and pin 1 of U3 with a scope (meter set to 2N).
Pin 14 350Hz - 400Hz 5Vpp.
Pin 1 350Hz - 400Hz .14Vpp.
A. No signal at pin 14.
1. Check R40 - R43, C12, C13, and IC3.
B. No signal at pin 1 but present at pin 14.
1. Check R44, R45, VR1, D6, and D7.
Pin 8 350Hz - 400Hz .3Vpp.
C. No signal at pin 8.
1. Check R46 - R48, D8, D9, C14, and
C15.
h
FE
Section
1. Check for shorts on socket pins.
2. Measure across base (B) terminal to COM
terminal for 209k
Ω
to 231k
Ω
.
A. Lower or higher than value; Check R49
(NPN) and R50 (PNP).
Decimal Point Section
1. Displays two decimal points.
A. Shorted resistors R7 - R9.
2. No decimal points displayed.
A. Check R7 - R9.
Diode
1. Measure voltage across V OHM and COM
terminal (set in diode mode) = 3V.
A. Low voltage, check R51, R53, and R54.
Buzzer
U2 Voltages
Pin 1 of IC2 - 1.5kHz.
-26-
No Sound Sound
Pin 1 –5.5 Pin 1 –1.87
Pin 2 –5.5 Pin 2 –1.87
Pin 3 –5.5 Pin 3 –1.87
Pin 4 3 Pin 4 3
Pin 5 0 Pin 5 0
Pin 6 3 Pin 6 0
Pin 7 –5.5 Pin 7 1.87
1.6Vpp
6V
-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-black-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-brown
Answ ers to Resistor Reading Ex ercise: 1) 400
Ω
+1%; 2) 90k
Ω
+.5%; 3) 12.7k
Ω
+1%; 4) 5.05k
Ω
+.5%; 5) 100
Ω
+1%;
6) 158k Ω +1%; 7) 9M Ω +.5%; 8) 9 Ω +.5%; 9) 100k Ω +.5%; 10) 39.2k Ω +1%; 11) 890 Ω +1%; 12) 11k Ω +1%;
Before starting assembly of your digital multimeter
project, you should be thoroughly familiar with the 5
band color code system. Many of the resistor values
will be identified by color bands and it is easy to
mistake their value if you read the colors incorrectly or read the value from the wrong end. Do the
following exercise in resistor values. Place your
answer in the box beneath the resistor. Answers are
on the bottom of this page.