Meter display circuit, Parts identification, Troubleshooting guide – Elenco 3 1/2 Digit Cap. / Trans. Kit User Manual

Page 26

Advertising
background image

-10-

PARTS LIST - SECTION A

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

®

(address/phone/e-mail 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

Description

Color Code

Part #

r

2

R4, R5

100k

Ω

5% 1/4W

brown-black-yellow-gold

161000

r

1

R3

200k

Ω

5% 1/4W

red-black-yellow-gold

162000

r

1

R1

220k

Ω

5% 1/4W

red-red-yellow-gold

162200

r

3

R7, R8, R9

470k

Ω

5% 1/4W

yellow-violet-yellow-gold

164700

r

2

R2, R6

1M

Ω

5% 1/4W

brown-black-green-gold

171000

CAPACITORS

Qty.

Symbol

Value

Description

Part #

r

1

C5

100pF (101)

Disc

221017

r

1

C1

.1

μ

F (104)

Mylar (large brown)

251017L

r

3

C2, C3, C4

.1

μ

F (104)

Mylar (small yellow)

251017S

r

1

C6

22

μ

F

Electrolytic (Lytic)

272244S

SEMICONDUCTORS

Qty.

Symbol

Value

Description

Part #

r

1

T1

9013

Transistor 2SC9013

329013

MISCELLANEOUS

SECTION A

Meter Display Circuit

Resistor

PARTS IDENTIFICATION

Diode

PC Board

Liquid Crystal Display (LCD)

Qty.

Description

Part #

r

1

LCD

351166

r

1

Zebra

500007

r

1

PC Board M2666K

512666

r

1

Switch On/Off (SW1)

540004

r

1

Battery 9V

590009

Qty.

Description

Part #

r

1

Battery Snap (Batt)

590098

r

1

LCD Housing

629015

r

1

LCD Cover

629016

r

1

Label Top

723051

r

2

Solder

9LF99

Transistor

Label Top

Display
Housing

Display
Cover

Zebra

LCD

Capacitors

Disc

Lytic

Mylar

C1

-25-

U1 (7106) Voltage Test

1. Measure the voltage across pin 8 and pin 34 on

U1 (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. Remove

one IC at a time and check voltage
again between pins 8 and 34.

2. Measure the voltage from pin 8 to COM on U1 for

3V.

A. U1 is defective.

3. Check the Main Oscillator on U1 (7106) pins 6, 7,

and 4.

Pin 6

Pin 7

Pin 4

4. 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. Can’t set to 100mV.

a. VR1 wrong value or defective.
b. R30 - R32 wrong value.

Voltage/OHM Section

1. Measure across V

Ω

CAP terminal and COM

terminal for 10M

Ω

(set meter in 200mV) battery

installed.

A. Lower or higher than 10M

Ω

.

1. Check resistors R10 - R18.

2. LCD readings floating.

A. Measure from COM terminal to pin 43 on

U1 (7106) for 220k

Ω

.

1. R3 open or defective.

AC Voltage Section

1. Apply 15VAC to meter and measure pin 14 of U2

(324) to COM terminal with a scope (meter on
20VAC scale).

Pin 14 to COM 2Vpp

A. Check IC2 and R34

2. Check junction R39 and C11 of U1 (7106) with a

scope.

Waveform for junction R39 and C11.

A. Check R35 - R39, C7 - C11, D3 - D5, and

VR2.

.16Vpp

If the meter is not working, perform the U1 (7106)
Voltage Test first. This test is to verify that the IC and
Reference Voltage are operational. Then perform

the tests that pertain to the Function that is not
working on your meter.

TROUBLESHOOTING GUIDE

.03Vpp

0V

Advertising