Heathkit RS 232C Manual

Page 2

Pa9e2

Heathkit

PARTS LIST

Remove the parts from the carton and check each
part against the following list. The key numbers cor-
respond to the numbers on the Parts Pictorial" [Il-
lustration Booklet. Page 1). Return any part that is
in an individual envelope back into the envelope
after you have identified it until that part is called
for in a step. Do not throw away any packing mate-
rial until you account for all the parts.

KEY HEATH QTY. DESCRIPTION CIRCUIT
& Part No. Comp. No.
RESIST ORS

NOTE: All resistors are 1/4-watt, 5%.

Reierdirectiymthoenelosedreslstor/dlodesheetandtollow
IheMUdIuIsatthetopotthatsheettocheokywrresistors
anddiodee.

A1 s-1a1-12 2 1800(brn-gry-brn) 3401. Race
A1 8471-12 1 470 n (yeI-viol-brn) am

A1 5102-12 1 1000 n (hm-blond) R402

A1 5472-12 1 4700 n (yeHIoI-red) mos

A1 ewe-12 1 10 m (hm-bloom) mos

A1 6223-12 1 22 I10 (MM-org) R404

A1 W12 2 as m (org-arm) R407. mos
A1 6404-12 1 100 m (bur-bli-yei) R409
CAPACITORS

BI 21-199 1 1 uF ceramic C426

31 21 -1 40 1 W1 uF ceramic 042!

32 25-838 1 3 3 of tantalum electrolytic C404

83 25-800 1 10 pF Myth: 0405

BS 25-885 I 100 of eiearotytic C401

34 27-71 1 1 F Mylar owe

54 27-181 1 01 uF Mylar c402
DIODES

CI 56-16 1 1N5231 zener 2401

C1 5&56 1 1N4149 D401

TRANSISTORS - INTEGRATED CIRCUIT

NOTE: The translstor and Integrated circuit may be marked
tor Identification In any one of the Iollowing tour ways:

To order a replacement part, always include the
PART NUMBER. Use the Parts Order Form fur-
nished with this kit. If a Parts Order Form is not
available, refer to Replacement Parts" inside the
rear cover of this Manual.

KEY HEATH
No. PartNo.

QTY. DESCRIPTION CIRCUIT

m

1. Part number.

2. Type number. (On the integrated circuit. use only those
numbers and letters In BOLD print. Disregard any
other numbers or letters.)

3. Part number and type number.

4. Part number with a type number other than the one
shown.

CAUTION: The IC is protected against damage caused by
static electricity. Do NOT remove the IC from its team pad
until you are instructed to do so in a step.

D1 417-801 2 MPSA20 transistor 0401. 0402
D2 444-2934 1 3870 programmed U401
microprocessor
MISCELLANEOUS
E1 45-608 1 39 pH coil L402
E1 45-609 1 2.2 .111 mil L401
:2 eo-ase 1 Dip switch 5401
E8 252-2 2 4-40 nut
E4 54-0 2 #4 Iodtweeher
E5 255757 2 4-40 X 3/18 hum
347-55 12' Mrs ribbon ediie
E6 390-2488 1 Function Iebel'
346-1 3" Fberaieeving
. 346-35 3' Heat-ohm shoving
E7 1 Blue and white label
Ea «2-134 2 Wire oonneota
E9 432-068 4 Spring oonneaor
(one extra)
£10 432-1032 1 PIS-2320 connector
E11 432-1033 4 Gold pin (one extra)
E12 432-1129 I 41am plug
513 432-1151 1 m m
E14 434-253 1 Huh IC socket
E15 438-55 1 PoIarlzlng plum
597-3263 1 Resistor/Diode sheet
1 Instrualon Mutual (see from
M0 '0' Pin number)
Solder

'Located Inside the Manual. Set it aside until it is called Ior later.

Page 11

Heathkit"

Page

THEORY OF OPERATION

Refer to the Schematic [supplied with the GC/GCW-
1000) as you read the following Theory Of 0pera~
tion."

The RS-232C Output Accessory. Model GCA-1000-1,
receives the WWV (or WWVH) time and date infor-
mation from the Clock microprocessor (1C U203)
every 10 milliseconds (ms). The RS-232C micropro-
cessor (IC U401) then converts the date from the Ju-
lian format into the standard month and day format.
It then reads the year you have selected via the bi-
nary coded switches. It computes the year by adding
the decimal equivalent of this binary code to the
number 83." Next, it corrects the month and day
for leap year and your selected time zone.

lC U401 then checks to see if there has been a request
by your computer to send this time and date infor-
mation to it. If no request has been sent. the micro-
processor repeats the process described previously.
(The request to send the information requires a low-
to-high voltage transition at pin 4 of P401. This volt-
age is coupled through resistor R404 and capacitor
C402 to cause transistor Q402 to briefly turn on and
pull pin 38 of U401 to a low state.)

SPACES

/\

In the normal mode (S401 switch setting), the micro-
processor is looking for the request-to-send signal.
When it receives this signal. the microprocessor (IC
U401] waits 1.00 seconds to allow time for your
computer to get ready to receive the time and date
information. The microprocessor then determines
the BAUD rate, (S401 switch setting) and the number
of stop hits 0401) that you have selected, and a trans-
mission is made. In the auto mode [S401 switch set-
ting), the microprocessor sends time and date infor-
mation continuously with no delay. (See the RS-232
function label on the inside of the cabinet top for
S401 switch settings). The microprocessor sends the
time and date in ASCII format through pin 2 of P401
via transistor Q401.

When this transmission is completed, it will send
the ASCII character for a carriage return (DD in
hexadecimal) to signal your computer that it is done
sending the information. NOTE: If you are operating
in the normal mode, the next transmission of infor-
mation will be 1.00 second slow at the beginning
of the transmission. Thus, you must make the neces-
sary corrections for this, the BAUD rate used, and
the execution time of your program to preserve the
accuracy of time, if needed.

An example of the format that is sent is as follows:

CARRIAGE
RETURN

09:12:52.3-AM-06/23/87 0

TIME E/day/yr'
Same zone & format as There will \Thmjzte is corrected
displayed on the clock be spaces to the time and the
(except no leading zero it the 24 year that is selected
blanldngontha103 hourmode via switch S401
othoun). is selected. '