Heathkit HD 1984 Schematic

Page 1

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DINISSIO

"lulu u :3 CW

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mavcnu ttlmuu. sue-rte
'0 COMMON MN nu :5

NOTES:

SCHEMATIC or THE
HEATHKIT®

MICODERTMII
MODEL HD-1984

l. REFER TO THE CIRCUIT BOARD X-RAY VIEW FOR THE PHYSICAL
LOCATION OF PARTS.

2. RESISTORS ARE 1/4 WATT, 10% TOLERANCE UNLESS OTHERWISE

INDICATED. RESISTOR VALUES ARE IN OHMS IK-IODO, III-1.000.000).

3. DC VOLTAGE MEASUREMENTS WERE TAKEN WITH A HIGH INPUT
IMPEDANCE VOLTMETER FROM THE POINTS INDICATED TO
CIRCUIT BOARD GROUND. VOLTAGES MAY VARY 1101-.

I DENTI'IC AT ION
OF KEYBOARD Pl NS

THIS SYMBOL INDICATES A DC VOLTAGE WITH NO TONI:
BEING PRODUCED AND PTT SWITCH ACTUATOR DEPRESSED.

THIS SYMBOL INDICATES A DC VOLTAGE WITH KEY "I
PUSHED AND PTT SWITCH ACTUATOR DEPRESSED.

THIS SYMBOL INDICATES CIRCUIT BOARD GROUND.

THIS SYMBOL INDICATES COMMON GROUND
THIS SYMBOL INDICATES A CONNECTION TO THE CIRCUIT

B 0A R D ,
Low
Tone (Hz) 1209

High Tone I Hz)

1336 1477
I
,, 697 1 2 3
770 4 s 6
852 7 8 9
941 ' #

Two-tone output frequencies from the Micoder.

r--------------1

| KEYBOARD

1

I-

_.._.f.....

I

I

h--------------J

. CIRCUIT BOARD

442-638

PIOI
Efl- 3563.795 m

V101

1

Copyright © 1977

All

Heath Company
Rights Reserved

Printed In the United States of America
Part of 595-1963-01

R108
2200

RED

MICROPHONE

BLK

____co~rnor.