Heathkit GC 1195 Manual

Page 1

HEATHKIT®

for the

DIGITAL FLOOR CLOCK
DIGITAL SHELF CLOCK
Model GC-1195/GC-1197

595-1886-02

HEATH COMPANY - BENTON HARBOR, MICHIGAN

Page 2

Price $2.00

Heathkit® Manual

for the

DIGITAL FLOOR CLOCK
DIGITAL SHELF CLOCK
Model GC-1195/GC-1197

595-1886-02

DIGITAL FLOOR CLOCK
MODEL GC-1195

(floor model pictured]

DIGITAL SHELF CLOCK
MODEL GC-1197

Copyright © 1976

Heath Company

H E AT H c O M PA N Y All Rights Reserved
BENTON HARBOR, MICHIGAN 490 2 2

Printed in the United States 0! America

Page 38

PLACEMENT

If you place the Digital Floor Clock on a shag or
heavily sculptured carpet. it is a good idea to place
some additional weight inside the base of the Clock to
make it more stable. To do this, cut a 1/2 x 7" x 11"
piece of plywood and place it inside the base of the
Clock: then place weight, such as several bricks. on
the plywood in the base.

Do not cover the ventilation slots in the top of the
Digital Shelf Clock. Also. do not place the Clock in
direct sunlight. as this will cause excessive heat
buildup.

Page 37

-HEATHI{IT"'|

CLEANING

You can use any good quality furniture polish on the
wood cabinets to maintain their appearance. Wipe
dust from the display window with a soft cloth. If
smudges still remain. clean the window with a
non-caustic window cleaner and a soft cloth. Be
careful that you do not scratch the plastic window in
the Digital Shelf Clock.

OTHER CONSIDERATIONS

You can create special display effects by using
translucent colored film (not available from Heath
Company) in place of the diffuser window that is
supplied.

IN CASE OF DIFFICULTY

Begin your search for any trouble that occurs after
assembly by carefully following the steps listed
below in the Visual Tests. After you complete the
Visual Tests. refer to the Troubleshooting Chart."

NOTE: Refer to the Circuit Board X-Ray Views" on
Page 42 for the physical location of parts on the circuit

board.

VISUAL TESTS

'1. Recheck the wiring. Trace each wire in colored
pencil on the Pictorial as it is checked. It is
frequently helpful to have a friend check your
work. Someone who is not familiar with the
unit may notice something consistently
overlooked by the kit builder.

2. About 90% of the kits that are returned to the
Heath Company for repair do not function
properly due to poor connections and soldering.
Therefore. many troubles can be eliminated by
reheating all connections to make sure that they
are soldered as described in the Soldering"
section of the Assembly Notes." Be sure there
are no solder "bridges" between circuit board
foils.

3. Check to be sure that all transistors and diodes
are in their proper locations. Make sure each
lead is connected to the proper point. Make sure
that each diode band is positioned above the
band printed on the circuit board.

4. Check the values of the parts. Be sure in each
step that the proper part has been wired into the
circuit. as shown in the Pictorial diagrams. It
would be easy. for example. to install a 1200 Q
(brown-red-red) resistor where a 2200 n
(red-red-red] resistor should be installed.

5. Check for solder bits, wire ends, or other foreign
matter which may be lodged in the unit.

6. A review of the Circuit Description" may also
help you determine where the trouble is.

if you still do not locate the trouble after you complete
the "Visual Tests." and a voltmeter is available. check
voltage readings against those shown on the
Schematic Diagram." NOTE: All voltage readings
were taken with an 11 MO input impedance
voltmeter. Voltages may vary as much as 20%.

In an extreme case where you are unable to resolve a
difficulty. refer to the Customer Service
information inside the rear cover of the Manual. Your
Warranty is located inside the front cover.

Page 42

Page 41

CIRCUIT DESCRIPTION

Refer to the Schematic Diagram [on a separate fold-in
sheet) while you read this Circuit Description.

CLOCK CIRCUIT

All time-keeping functions are performed by
integrated circuit IC101. 60 Hz pulses from the
transformer secondary (T1) are fed to IC101. pin 35.
This 60 Hz input signal is filtered by R1 1 1 and C103 to
remove any power line transients that could cause
miscounting.

IC101 counts and decodes the 60 Hz signal into

seven-segment display information. The outputs of

IC101 are individual DC voltages that drive transistor
switches 0201 through 0222. For example. a DC
voltage on 1C1 01. pin 3 causes transistor switch 0202
to turn on. which in turn lights lamp PL203.
Therefore. the Hours f segment is lighted. Since
lamps PL201 and PL202 form the 1 for the tens of
hours digit. and are always on together. they are
driven by a single transistor. 0201. Likewise. lamps
PL213 and PL215 are driven by transistor 0212 since
the tens of minutes segments "a and "d" are always
on together.

POWER SUPPLY CIRCUIT

The power supply is comprised of an unregulated
+18-volt source and a regulated +5-volt* lamp
source.

This voltage is not filtered and may not read 5 volts
on many voltmeters. This voltage also depends on the
LDR resistance and will be less in dim ambient light.

The unregulated +18-volt source is full-wave
rectified by diodes D101. D102. D103. and 0104 and
filtered by capacitor C101. This +18-volt source
supplies the power for IC101.

The power supply for the lamps is a regulated.
full-wave rectified +5-volt source. Transistor 0102
and resistors R102 and R103 sample the lamp voltage
from the emitter of transistor 01. If the lamp voltage is
too low. 0102 turns off. which allows more current to
flow to transistors 0101 and 01. This causes 0101
and 01 to turn on. thus increasing the lamp voltage.

LDR CIRCUIT

In dim ambient light. the LDR (light dependent
resistor) resistance increases. which turns on 0103
and increases the voltage feedback to 0102 through
R104. 0102 then turns on and decreases the current
flow to 0101 and 01. This results in a lower lamp
voltage and dimmer display. In bright ambient light.
the LDR resistance is low. which keeps 0103 turned
off and allows a bright display.

POWER FAILURE CIRCUIT

0104 receives a power failure signal from pins 1 and
40 of IC101. 0104 then modulates 0102 with one
pulse per second to indicate a power failure. A power
failure is indicated by a flashing display.

Page 45

Page 44

SEMICONDUCTOR IDENTIFICATION CHARTS

TIIISISTIIS

HEATH MANUFACTURER'S
COMPONEM PART NUMBER PART NUMBER BASE D'AGRAM

2N3416

0201.0202.
0203,0204,
0205,020@
0207,0208.
0209.0210.
0211.0212.
0213.0214.
0215.02lt
0217.0218.
0219,0220.
0221,0222

n 417-91 2N5232A
0103 417-200 X29A826

01 417-215 2N3055
COLLECTOR
EMITTER

0104 417-801 MPSAZO
n 7.8 _ mm

EMITTEP

Page 56

PICTORIAL 3-2