Heathkit GC-1005 User manual

" D D !L GC-1005 Electronic Clock
Copyright 01972
Heath Company
All rtgha rwiwtf
PRICE $2.00

TABLE OF CONTENTS
Assembly
and
Operation
of the
ELECTRONIC CLOCK
MODEL GC-1005
Introduction. 2
Parts List. 2
Assembly Notes . 4
Step-by-Step Assembly . 5
Cabinet Top .15
Cabinet Bottom.16
Alternate Line Voltage Wiring .17
Other Wiring .17
Decorating .20
Initial Tests . 2 1
Operation .22
In Case of Difficulty .23
Troubleshooting Chart.24
Specifications . 2 5
Circuit Fundamentals.26
Chassis Photograph . •.27
Circuit Board X-Ray Views .28
Circuit Board Voltage Charts .30
Identification Chart.31
Schematic.. .(fold-out from page) .31
Warranty.Inside front cover
Customer Service.Inside rear cover
HEATH COMPANY
BENTON HARBOR. MICHIGAN 49022

INTRODUCTION
The Heathkit Model GC-1005 digital Electronic Clock has
many attractive features, including: a wiring option that lets
it display either 12-hour or 24-hour time; an AM-PM alarm
with snooze alarm; a 6-digit, easy-to-read display; a power
interruption indication; a 50 or 60 Hz wiring option; and a
120-volt or 240-volt wiring option. The heart of the Clock is
an MOS/LSI * integrated circuit that performs all the logic
functions of keeping time.
A simple wiring option lets your Clock display either
12-hour or 24-hour time. The clock "knows" the difference
between AM and PM and will only sound the alarm for the
one time (either AM or PM, but not both) in 24 hours that
you desire. The snooze alarm waits approximately seven
minutes each time it is reset, until it sounds again.
'MOS/LSI (Metal Oxide Semiconductor/Large Scale
Integration)
The readout tubes clearly display the time on a sloped
surface, and the 6-digit display shows ail 8's if there is a
significant power line interruption. The Clock can be wired
to operate from either a 50 Hz or a 60 Hz power line, or 120
volts or 240 volts AC.
Attractive, modern styling; small size; and solid-state
dependability make this Clock ideally suited for your office,
your home, or almost anywhere.
Refer to the "Kit Builders Guide" for complete information
on unpacking, parts identification, tools, wiring, soldering,
and step-by-step assembly procedures.
PARTS LIST
Check each part against the following list. The key numbers
correspond to the numbers in the Parts Pictorial (fold-out
from Page 5). Any part that is packaged in an individual
envelope with the part number on it should be placed back
in the envelope after it is identified until it is called for in a
step.
CAUTION: The integrated circuit (#443-601) can be
damaged by static voltage. Do not handle it until you are
told to do so.
To order a replacement part, use the Parts Order Form
furnished with this kit. If a Parts Order Form is not
available, refer to "Replacement Parts" inside the rear cover
of the Manual.
KEY PART PARTS DESCRIPTION PRICE
No. No. Per Kit _ Each
RESISTORS
NOTE: Each of the following resistors has a 10% tolerance
unless otherwise noted. 10% is indicated by a silver fourth
color band, while 5% is indicated by a gold band.
1/4-Watt
A1 146-12 / 27 kft (red-violet-
orange)
.10
A1
1-12-12
0
82 kft (gray-red-
orange)
.10
A1 1-90-12
r)
91 kft, 5% (white-brown-
orange)
.10
A1 1-32 12
0
100 kft (brown-black-
yellow)
.10
A1 1-16-12
<9
180 kft (brown-gray-
yellow)
.10
KEY PART PARTS DESCRIPTION PRICE
No. No. Per Kit Each
1/2-Watt
n
A2 1-45
220 ft (red-red-brown)
JO
A2
1-13
ft) 2700 ft (red-violet-red) .10
A2
1-114 8200 ft, 5% (gray-red-
.20
A2 1-109
©
0
red)
12 kft, 5% (brown-
red-orange)
.20
A2
1-162
15 kft, 5% (brown-
green-orange)
.10
©
A2 1-22
22 kft (red-red-
orange)
.10
©
A2
1-23
27 kft (red-violet-
orange)
.10
©
<3
A2
147
56 kft (green blue-
orange)
.10
A2
1-121
120 kft (brown-red-
yellow)
.10

KEY PART PARTS
DESCRIPTION PRICE
No. No.
Per Kit
Each
Resistors (cont'dJ^.
A2 1-30
270 kS2 (red-violet-
.10
A2 1-33
<D
yellow)
470 kI2 (yellow-violet- .10
A2 1-35
CD
yellow)
1 MS3 (brown-black-
green)
.10
CAPACITORS
A3 20-100
30 pF mica .20
A4 21-163
&
.001 fi F disc
.10
A5 27-63
a)
.022 mF Mylar*
.10
A6 25-30
X
Dual 20 juF electrolytic
1.00
A7
25-241 S>
1200 *iF electrolytic
.90
DIODES
B1 56-25 i
1N4166A zener
1.00
B1 56-56 8 1N4149
.20
B1 57-27 1
1N2071
.50
B1 57-65
2 1N4002
.20
TRANSISTORS-INTEGRATED CIRCUIT
NOTE: Transistors and integrated circuits are marked for
identification in one of the following four ways:
1. Part number.
2. Type number. (In integrated circuits this refers
only to the numbers: the letters may vary.)
3. Part number and type number.
4. Part number with a type number other than the
one listed.
B2 417-811
7
MPS-L01 transistor
.40
B2 417-295
6
MPS-L51 transistor
.50
B2 417-801
8
MPS-A20 transistor
.20
B3 443-601
<D
MK5017AA integrated 15.00
circuit
SWITCH ESI NSULATORS
B4 60-1 SPST switch
.20
60-6 q) SPST switch with spring
.30
return
B5
60-2
©
DPDT switch
.30
B6
75-52
Switch insulator .10
B7 75-103 Fish paper. 5-1/2" x 1-7/8'
’* 10
B8 75-93
CD
Fish paper, 1" x 1"
.10
B9 75-138
fa)
Rubber foot
.10
CORD-WIRE-CABLE
8944 (3^ Line cord .55
* Du Pont Registered Trademark
KEY PART
PARTS
DESCRIPTION
No. No. Per Kit
Cord-Wire-Cable (cont'd.)
340-11
©
Bare wire (used only
O
for soldering iron tip)
344-50
Black wire
347-55
0
8-wire cable
HARDWARE
Cl
250420 7
2-32 x 1/4" self-tapping
screw
C2 250-52 3
440 x 1/4" screw
C3
252-2
3 440 nut
C4
254-9 3 #4 lockwasher
C5 250-276
12 6-32 x 3/8" flat
head screw
C6 250-381
2
6-32 x 3/8" black screw
250-89
1
6-32 x 3/8" screw
C7
250-1156
4
6-20 x 2-1/4” self¬
tapping screw
C8 252-3 3
6-32 nut
C9
253-60
2
#6 flat washer
CIO 254-1 5 #6 lockwasher
C11
259-1
6 #6 solder lug
CIRCUIT BO ARDS-CABINET-LAB ELS
85-1239-3
Q
Main circuit board
85-1240-2
vn
Display circuit board
D1
92-77 Cabinet top
D2 92-78 Cabinet bottom
D3 390-341
Heathkit label
390-362
(n
Fuse label
390-926 Cord disconnect label
390-995
O
Wood-grain trim
391-34
©
Blue and white label
MISCELLANEOUS
54-820
<D
Power transformer
El
204-1876
Angle bracket
E2 205-141 Tool plate
E3 258-167
©
Speaker clamp
E4
346-6 q)
Sleeving
E5
401-163 vu Speaker
E6 411-286 ( y Display tube
E7 412-11
cp
Neon lamp
E8 42140
<J>
3/16-ampere slow-blow
fuse
E9 43143 Terminal strip
E10 432-134
56'
Connector pin
Ell
432-144
©
Integrated circuit
(1C) connector
El 2
432-199
(5
Wire nut
PRICE
Each
.05/ft
.05/ft
. 25/ft
.05
.05
.05
.05
.05
.05
.05
.10
.05
.05
.05
.05
1.65
.85
1.20
1.10
.10
.10
.15
.40
4.60
.15
.10
.05
.05
1.40
5.00
.20
.40
.10
.10
.01
.10

KEY PART PARTS DESCRIPTION PRICE
No, No. Per Kit Each
Miscellaneous
E13 446-609
490-5
597-260
597-308
The prices apply only on purchases from the Heath
Company where shipment is to a U.S.A. destination. Add
10% (minimum 25 cents) to the price when ordering from a
Heathkit Electronic Center to cover local sales tax, postage,
and handling. Outside the U.S.A., parts and service are
available from your local Heathkit source and will reflect
additional transportation, taxes, duties, and rates of
exchange.
(cont'd.)
Window 1.20
Nut starter .10
Parts Order Form
Kit Builders Guide
Manual (See front cover 2,00
for part number.)
Solder (Additional 6' rolls
of solder, #331-13, can be
ordered for 25 cents each.)
ASSEMBLY
1. Before you start to assemble this kit, read the wiring,
soldering, and step-by-step assembly information in
the "Kit Builders Guide."
2. Due to the small foil area around the circuit board
holes and the small areas between foils, it will be
necessary to use the utmost care to prevent solder
bridges between adjacent foil areas. Use only a
minimum amount of solder and use no larger than a
25-watt soldering iron with a small tip. Allow it to
reach operating temperature, and then apply it only
long enough to make a good solder connection.
3. I f a small wattage, small-tip soldering iron is not
available, proceed as follows: Be sure your soldering
iron is cool. Wrap the large bare wire (supplied) tightly
around the soldering iron tip as shown in Figure 1.
Allow approximately 1/4" of wire to extend beyond
the end of the soldering iron. Cut the wire end to a
NOTES
chisel shape as shown. Occasionally apply solder to the
turns of large bare wire to achieve a good heat
transfer.
4. Resistors will be called out by their resistance value in
n, kfi, or MJ2, and color code.
5. Capacitors will be called out by their capacitance value
(in pF or u F) and type (disc, mica, Mylar, or
electrolytic).

Page 21
Refer to Figure 2 (fold-out from Page 23) to identify the
function of each switch.
NOTE: If you do not obtain the proper results in any of the
following steps, unplug the line cord plug and proceed to the
"In Case of Difficulty" section on Page 22.
( ) Set the six switches to the positions shown.
( ) Plug the line cord plug into an AC outlet. Each of the
six display digits should indicate an eight.
( ) Push the TIME HOLD switch to the right and back
again. The display should now indicate 12:00:00 or
00:00:00 and start keeping time.
( ) Push the Alarm Set switch to the right. The display
should now indicate 12:00:00 or 00:00:00 and the
AM-PM lamp should be on.
< ) Push and hold the HOURS SET AHEAD switch to the
right. The HOURS DISPLAY will now advance one
digit each half second. The AM-PM lamp will turn on
and off each six seconds.
( ) Release the HOURS SET-AHEAD switch.
{ ) Push and hold the MINUTES SET-AHEAD switch to
the right. The MINUTES DISPLAY will now advance
one digit each half second.
( ) Push both the MINUTES SET AHEAD switch and the
HOURS SET-AHEAD switch to the right. The tens of
minutes will now advance one digit each half second.
( ) Push the MINUTES and HOURS SET-AHEAD
switches as necessary until the MINUTES DISPLAY
indicates 45 minutes; then quickly release the
MINUTES SET-AHEAD switch.
Continue holding the HOURS SET-AHEAD switch
until the HOURS DISPLAY indicates 6 and the
AM-PM lamp is on (indicating AM). Then quickly
release the switch.
( ) Push the ALARM SET switch to the left.
{ ) Push the ALARM ON-OFF switch to the ON (down)
position.
( ) Push the TIME HOLD switch to the right.
( ) Push both the HOURS SET-AHEAD switch and the
MINUTES SET-AHEAD switch to the right as
necessary until the MINUTES DISPLAY indicates 44
minutes. Then quickly release the MINUTES
SET-AHEAD switch.
( ) Continue holding the HOURS SET-AHEAD switch
until the HOURS DISPLAY indicates 6 and the
AM-PM lamp is on (indicating AM). Then quickly
release the switch.
( } Push the TIME HOLD switch to the left. The clock
should now start keeping time and in approximately
one minute the alarm should sound.
( ) When the alarm sounds, push the SNOOZE ALARM
switch down (to reset the snooze alarm) and release
the switch. In approximately seven minutes, the alarm
should sound again.
( ) Push the ALARM ON-OFF switch up to the OFF
position.
This completes the "Initial Tests."
INITIAL TESTS
< )

OPERATION
Figure 2 (fold-out from Page 23) points out the switches and
displays of your Clock. These switches and displays are
further described below.
1. ALARM ON-OFF SWITCH - Turns the alarm on and
off. Down is on. NOTE: After the alarm sounds, if
you wish, you may turn the alarm off and
immediately return the switch to the ON position. The
alarm will then sound 24 hours later.
2. SNOOZE ALARM SWITCH - Resets the alarm to go
off seven minutes later.
3. HOURS SET-AHEAD SWITCH - Advances the
HOURS DISPLAY one hour each half second.
4. MINUTES SET-AHEAD SWITCH - Advances the
MINUTES DISPLAY one minute each half second.
3 and 4. When used together, they advance the
MINUTES DISPLAY ten minutes each half
second.
5. ALARM SET SWITCH — Allows you to set the alarm
using the HOURS and MINUTES SET-AHEAD
switches. Also allows the display to indicate the time
for which the alarm is set. (Time continues to be kept
even though it is not displayed when this switch is
being used.)
6. TIME HOLD SWITCH — Allows you to set the Clock
ahead to the desired time, using the HOURS and
MINUTES SET-AHEAD switches, and then start the
clock when the desired time arrives.
7. AM-PM LAMP — Indicates AM when on and PM when
off; only when setting the alarm or the time. The
Lamp is not on during normal operation.
8,9, and 10. HOURS, MINUTES, and SECONDS
DISPLAY — Indicate the time or the time
that the alarm is set for. Indicates all 8's
when first plugged in or when power has
been interrupted for several seconds.
TO SET THE TIME:
1. Push the TIME HOLD switch to the right.
2. Push the MINUTES SET-AHEAD and HOURS
SET-AHEAD switches (separately or together) as
necessary to advance the display to a desired time. Be
sure the AM-PM lamp is on or off as desired — on is
AM; off is PM.
3. Watch another clock. When the time gets to the time
on the display, push the TIME HOLD switch to the
left.
TO SET THE ALARM:
1. Push the ALARM-SET switch to the right. (The clock
will continue to keep time, even though the display is
stationary.)
2. Push the MINUTES SET-AHEAD and HOURS
SET-AHEAD switches (separately or together) as
necessary to advance the display to a desired time. Be
sure the AM-PM lamp is on or off as desired - on is
AM; off is PM.
3. Push the ALARM-SET switch to the left.
4. Push the ALARM ON-OFF switch down to the ON
position.
FOR DAYLIGHT SAVINGS TIME:
1. Push the HOURS SET-AHEAD switch to the right and
advance the HOURS DISPLAY to the desired hour.
NOTE: To go back an hour, advance the display 23
hours.

IN CASE OF DIFFICULTY
This section of the Manual is divided into two parts. The
first part, titled "General Troubleshooting Information,"
describes what to do about the difficulties that may occur
right after your Clock is assembled.
The second part, titled "Troubleshooting Chart,” is provided
to assist you in servicing the Clock if the "General
Troubleshooting Information" fails to clear up the problem,
or if difficulties occur after your Clock has been in use for
some time. The "Troubleshooting Chart" lists a number of
possible difficulties that could arise along with several
possible solutions to those difficulties.
Try to analyze the symptoms of any problem you might
have before starting any troubleshooting procedure. This can
usually be accomplished by trying the various functions of
your Clock to determine abnormal operations. A review of
the "Operation" section above may help your analysis.
NOTE: Refer to the "Circuit Board X-Ray Views" on Pages
28 and 29 for the physical location of parts on the circuit
boards.
GENERAL TROUBLESHOOTING INFORMATION
1. Check all the wires that are connected between the
two circuit boards and between the circuit boards and
other parts. Trace each wire in colored pencil on the
Pictorial as it is checked. Make sure these wires are
connected to the proper points and are properly
soldered. Someone who is not familiar with the unit
may notice something you have consistently
overlooked.
2. Be sure the 1C is seated properly in its socket.
3. About 90% of the kits that are returned for repair do
not function properly because of poor connections
and soldering. Therefore, many troubles can be
located by a careful inspection of connections to make
sure they are soldered as described in the "Soldering"
section of the "Kit Builders Guide." Reheat any
doubtful connections.
4. Closely examine each circuit board foil in a good light
to see that no solder bridges exist between adjacent
connections. If available, a magnifying glass would be
helpful for this purpose. Remove any solder bridges by
holding a clean, hot soldering iron tip between the two
points that are bridged until the excess solder flows
down onto the tip. Compare your foil pattern against
the "X-Ray Views" on Pages 28 and 29.
5. Be sure each transistor is in its proper location (correct
part number and/or type number). Be sure that each
transistor lead is in the right hole and has a good
solder connection to the foil.
6. Check the integrated circuit for proper positioning.
(Be sure the dot or notched end of the 1C is over the
half dot printed on the circuit board.)
7. Check each capacitor value. Be sure that a capacitor of
correct value is installed at each capacitor location.
Check each electrolytic capacitor to be sure the lead
near the positive (+) marking is at the correct position.
8. Check each resistor value carefully. It would be easy,
for example, to install a 2200 ft (red-red-red) resistor
where a 22 kft (red-red-orange) resistor is called for. A
resistor that is discolored, or cracked, or shows any
sign of bulging would indicate that it is damaged and
should be replaced. Since damaged resistors are often
the result of some other difficulty (such as faulty
wiring), you should try to find out what caused the
damage before you replace the part.
9. Be sure the correct diode is installed at each diode
location, and that the banded end is positioned
correctly.
10. C heck all component leads connected to the circuit
boards. Make sure the leads do not extend through the
circuit board and come in contact with other
connections or parts.
If you still cannot locate and correct the trouble after the
above tests are completed, and if a voltmeter is available,
check your Clock's voltages against the voltages shown on
the Schematic Diagram (fold-out from Page 31) and in the
"Circuit Board Voltage Charts" (Page 30).
NOTE: 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. Vour Warranty is
located inside the front cover of the Manual.
( WARNING: Hazardous voltages are exposed in the Clock
when the cabinet top is removed and the line cord is plugged
into the AC outlet. See "Chassis Photograph " on Page 27.

Figure 2