WhitakerAudio J C Whitaker 20 W Stereo Audio Amplifier, Manual

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20 W Stereo Audio Amplifier
3.1.4 Speaker Terminal PWBs
A small PWB is used at each of the speaker terminals to facilitate connection of the output
transformer secondary leads and for the feedback circuit. The left and right channel boards are
identical, except for placement of certain components to accommodate attachment to the rear
panel speaker barrier strips. The connection terminals are listed in Table 3.4.
The layout of the speaker terminal board is shown in Figure 3.4.
Table 3.4 Speaker PWB Connection Wiring Codes
(Note that the color codes for the transformer listed in this table may vary. Consult
device documentation before proceeding.)
PWB Code Function Connection
Color Code Notes
GND Chassis ground Black Connected to main ground point
RYL Relay input voltage (+35 V dc) Yellow To front panel Speaker switch
(not used on 40 W amplifiers)
GND Ground Shield Circuit ground
(not used on 40 W amplifiers)
HEAD1 Headphone output #1 White To headphone jack J1 on front
panel
(not used on 40 W amplifiers)
HEAD2 Headphone output #2 Black To headphone jack J2 on front
panel
(not used on 40 W amplifiers)
Conn5
1 Ground Shield Circuit ground
2 Feedback circuit to amplifier White To main amplifier PWB feedback
circuit input
3 Ground Shield Circuit ground
4 Isolated speaker output White To power management “silence
detector” input
Conn6
1 Output transformer secondary
common Black T1 secondary common to circuit
ground
2 4
Ω
secondary output Green T1 secondary 4 ohm lead
3 8
Ω
secondary output Yellow T1 secondary 8 ohm lead
4 16
Ω
secondary output White T1 secondary 16 ohm lead