Heathkit AR-14 - Installing Transistors

Page 36
INSTALLING TRANSISTORS
Refer to Detail 24A for the following steps.
( ) Locate both transistors #417 -100 (2N3053),
both transistor mounting plates , and both
heat sinks. Position the heat sink with the
rivet side as shown, and then mount the parts
on both heat sinks as described in the
following steps.
( ) Note that the leads of each transistor are
grouped near one side of the transistor.
The emitter (E) lead is the one closest to
the locating tab. The next lead, the one
nearest , to the emitter lead, is the base (B)
lead. The remaining lead is the collector
(C) lead. Install the transistor in the heat
sink with the emitter and collector leads
opposite the indicated small holes.
( ) Install a transistor mounting plate on the
heat sink with 4-40 x 5/ 16" self-tapping
screws. Position the transistor leads
through the large hole in the plate.
( ) Install heat sinks on the circuit board at Qll
and Q12. See Pictorial 24. Insert the tran-
sistor leads through their respective holes
C, B, and E, and insert the spade bolts
through the mounting holes. Use #6 lock-
washers and 6-32 nuts on the spade bolts.
( ) Solder the transistor leads to the foil side
of the circuit board. Make sure the leads
do not touch each other or the transistor
mounting plate.
Refer to Detail 24B for the following steps.
Install the shield on the circuit board at
the location shown in Pictorial 24. Use #6
lockwashers and 6-32 nuts.
Refer to Pictorial 24 and install two 2500
µfd electrolytic capacitors on the circuit
board with the positive (+) leads positioned
as shown. Solder the leads to the foil side
of the board.
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SMALL HOLE
EAT SIN
~
I
~:
t
MOUNTING
' I PLATE
RIVET I
HEAD ~: 1 - ~ ~
___,.::::;;:;1 ~ %<::ii ~·~ 'tt, :.----
~······· ~x i - §-;;;; ~~;._,~ _ 40x5 / 16 "
' ~•::;:, ~NQ•U~ SELF - TAPPING
l ~>~~ ~
::,: . E ~~
•,•. >+""'"'====::.,.B , : • ')~]Ni;Ri
~"'• ~~~.......,. '7; ~/~:: KWASHER
$ @ 6 -3 2 NUT
CIRCUIT
BOARD
SHIELD
~
Detail 24A
Detail 248