Heathkit IM 4120 Schematic

Page 1

SCHEI
HI

MODEL IN
FREQUENC

Part of 595-1917/595-1913

NOTES:
1. COMPONENTS ARE NUMBERED IN THE FOLLOWING GROUPS;

1. 9? MOUNTED ON CHASSIS.
101-199 MOUNTED ON INPUT CIRCUIT BOARD.
201-299 MOUNTED 0N DISPLAY CIRCUIT BOARD.
3017399 MOUNTED ON MAIN CIRCUIT BOARD.

2. v THIS SYMBOL INDICATES A CIRCUIT BOARD
THIS SYMBOL INDICATES CHASSIS GROUND.

0 THIS SYMBOL WITH A LETTER INDICATES A C
BOARD WIRE CONNECTION, THIS SVMBOL W
NUMBER INDICATES A CIRCUIT BOARD-TO-C
CWVHQM©19TI BOARD"F-PIN" CONNECTION.
Heath Company
New? 5 O WT#XISIIIIII'ACIIESH".IIEIIITéEGINIu"
PNmadlnIhQUnmd MAM METER FROM THE POINT INDICATED T0 CIRCI
GROUND.

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Page 2

SCHEMATIC OF THE

HEATHKIT®

IODEL IM-4120 / SM-4120
IEGUENCY/PERIOD METER
m V nus SYMBOL INDICATES A CONNECIION 10 A
)WING GROUPS: VOLTAGE SOURCE
BOARD.
[1 BOARD. 7. O IHIS svmam INDICATES A TEST POINT,
IOARUI
IRCUIT BOARD GROUND. a. #617 ARRow INDICATES CLOCKWISE ROIATION.
I55Is GROUNDI
9- ALL RESISTORS ARE l/dWATT, 57h UNLESS MARKED OTHERWISE.
INDICATES A cmcun RESISTOR VALUES ARE IN OHMS mono, M-I,ooo,oum.
HIS SYMBOL WITH A
IT BOARD'TOCIRCUIT 10 ALL CAPACITORS ARE IN "E IMICROFARADS] UNLESS MARKED
OTHERWISE.
c vomcz MEASURE- 11. PARTS IN SHADED AREAS ARE CRITICAL FOR commuw sAmv.
PEDANCE INPUT VOLT> REPLACE THEM ONLY WITH PARTS OF THE SAME RATING OR WITH
:ATED TD CIRCUIT THE PROPER HEATH PARTS,
12. IC PINS NUT SHOWN, ARE NOT CONNECTED IN THE CIRCUITS.

LOGIC l
I .
CMOS I T
I
+5v
I
3.5ov :
MIN I
, +2.0v
L 5v I MIN
MAX Lav
W IMAX

THESE LOGIC LEVELS ARE THE Ml
YOU SHOULD FIND WHEN TRUUBLI

:DTé'fi'L'AY CIRCUIT" Bo'ARD'T

-\-----__

cm ,
ISDMF

mm
no

___ . -..-_ ----- --.. ---- _
SCHM'I'
El?- AMFLIFIER AMPLIFIER 6515:

ICZSOI
vm mm

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