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Model 3476A
7-24. Printed Circuit Board Removal.
7-25. Remove the Al printed circuit board assembly using
the following procedure:
a.
Disconnect power cord, remove input
fuses and
bottom shell. Leave the aluminum bottom shield fastened
to the PC board.
b.
Disconnect positive and negative battery terminals.
c.
Remove heat sink from Q100.
d.
Remove two polycarbonate spacers.
e.
Remove 4 PC board mounting screws — one on each
side of the switch assembly and the other two in each
corner at the back of the PC board.
f.
Pull J4 and J5 free from the top shell.
Section VII
g.
Using transformer T101 as a handle, lift the PC
assembly out of the top shell back first until it is above the
onsert nuts. The Al Assembly will now slide back and clear
of the top shell.
Handle the PC assembly by the transformer
(T101) and the pushbutton switches.
To avoid possible damage to the PC assembly,
do not use plastic or bubble pack as a packing
material.
Use
non-static
charge
producing
materials such as conductive foam (-hp- Part
No. 9220-1776).
GENERAL SCHEMATIC NOTES
1. PARTIAL
REFERENCE
DESIGNATIONS
ARE
SHOWN.
PREFIX
WITH
ASSEMBLY
OR
SUBASSEMBLY
DESIG-
5,
NATION(S) OR BOTH FOR COMPLETE DESIGNATION.
2. COMPONENT VALUES ARE SHOWN AS FOLLOWS UN-
LESS OTHERWISE NOTED.
RESISTANCE IN OHMS
CAPACITANCE IN MICROFARADS
INDUCTANCE IN MILLIHENRYS
DENOTES EARTH GROUND.
USED FOR TERMINALS WITH NO LESS THAN A
•
NO.
18
GAUGE
WIRE
CONNECTED
BETWEEN
TERMINAL AND EARTH GROUND TERMINAL OR
AC POWER RECEPTACLE.
DENOTES
GROUND
ON
PRINTED
CIRCUIT
ASSEMBLY. ( PERMANENTLY
CONNECTED
TO
FRAME GROUND).
DENOTES Ul HYBRID.
1
9 465U1 PIN CONNECTOR.
6.
ellie
DENOTES ASSEMBLY.
DENOTES SCREWDRIVER ADJUST.
7. *
AVERAGE VALUE SHOWN, OPTIMUM VALUE SE-
LECTED
AT FACTORY. THE
VALUE
OF
THESE
COMPONENTS
MAY
VARY
FROM ONE
INSTRU-
MENT TO ANOTHER. THE METHOD OF SELECTING
THESE COMPONENTS IS DESCRIBED IN SECTION V
OF THIS MANUAL.
8.
924
DENOTES WIRE COLOR: COLOR CODE SAME AS
RESISTOR COLOR
CODE. FIRST NUMBER IDEN-
TIFIES
BASE
COLOR, SECOND
NUMBER
IDEN-
TIFIES WIDER STRIP, THIRD NUMBER IDENTIFIES
NARROWER
STRIP. ( e.g. \ 22jii = WHITE,
RED,
YELLOW.)
9.
DC
VOLTAGE
LEVELS
WERE
MEASURED
WITH
RESPECT TO CIRCUIT GROUND USING A DVM WITH
10
MEGOHM
INPUT
IMPEDANCE.
THE
VOLTAGE
LEVELS
SHOWN
ARE
NOMINAL AND MAY
VARY
FROM
ONE
INSTRUMENT
TO
ANOTHER
DUE
TO
CHANGE
IN
TRANSISTOR
CHARACTERISTICS.
A
VARIATION OF t 10% SHOULD BE ALLOWED.
7-3
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