WhitakerAudio J C Whitaker 20 W Stereo Audio Amplifier, Manual

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20 W Stereo Audio Amplifier
5.2 Assembly of the 20 W Stereo Amplifier PWB #2 (Left Channel)
Check the shipping box for the major component groups. Find the 20 W Stereo Amplifier PWB
#2 (Left Channel) box. Set the other boxes aside for now. Organize the components for the left
channel amp in a logical manner, grouping resistors together, capacitors together, and so on. Note
that a schematic diagram of the amplifier is provided, along with a copy of the PWB component
layout. The component layout sheet is a useful reference as many of the part numbers are
obscured when the components are installed. The estimated time required to complete assembly
of the left channel PWB is two hours.
After reviewing the Construction Techniques section of this manual, begin populating the
board. As the packing envelopes are used, set them aside for recycling. Before beginning, clean
the soldering iron tip.
– Install the “quick disconnect” male tabs using the pads provided on the board. There are
25 positions in all. Solder in place.
Note that the mounting pins fit tight into the board. This is normal. Use a pair of pliers to hold
the tab while inserting the pins into the PWB. Make sure the PWB is resting on a soft flat surface
while the tabs are installed. It is most efficient to install all of the tabs and then turn the board over
and solder in place. Be careful to not damage the board while installing the tabs. While not strictly
necessary, it is recommended that the flat side of the tab be oriented so as to face the same
direction for all posts.
The proper procedure is illustrated in Figure 5.1.
Clean the soldering iron tip before moving on to the following steps.
– Install R18 – 1 m
Ω
, 0.5 W . Solder in place.
Caution: leads may tend to fly toward the face when they are cut. Wear protective glasses. For
all steps that follow, excess lead length should be trimmed after the component is soldered in
place.
– Install R19 – 10 k
Ω
, 0.5 W . Solder in place.
– Install R20 – 820 k
Ω
, 0.5 W . Solder in place.