Fisher CA-271 - Recommended Test Equipments; Harmonic Distortion Test

RECOMMENDED TEST EQUIPMENTS
The following test equipments are recommended to completely test and align the Amplifier:
Line Voltage Isolation Transformer
AC DC Multimeter
Accurately Calibrated AC Voltmeter
Oscilloscope (Flat to 100 kHz Minimum)
e Low-Distortion Audio Sine-Wave Generator
e Harmonic Distortion Analyzer
¢ Two (2) Load Resistors 8-ohms, 250 Watts
(Minimum Rating)
ee HARMONIC DISTORTION TEST
CAUTION: Limit the following tests to no more than ten
minutes each. Use 8-ohm resistors, with a minimum
power rating of 250 watts when connecting a load across
the SPEAKERS terminal.
CONTROL SETTINGS:
Unplug the AC power cord and set the front panel
controls as follows:
e GRAPHIC EQUALIZER to center position.
e BALANCE control to center position.
e POWER switch to OFF
e SPEAKERS switch to OFF
e FUNCTION switch to AUX/VIDEO
e LOUDNESS switch to OFF
e VOLUME control to MINIMUM position
e LEFT CHANNEL DRIVEN
ONE CHANNEL DRIVEN:
1) Connect a low distortion audio generator to L==~
AUX IN jack. Set generator frequency to 1 kHz 472
output to minimum.
2) Connect an 8-ohm load resistor between SPE4“ -
ERS SYSTEM-A LEFT and COM terminals. Cor’ 472:
a Harmonic Distortion Analyzer and an AC VT /‘" -
parallel across the 8-ohm load.
3) Connect the AC power cord and set SPEA“*=
switch to ON position. Turn VOLUME con?7~
MAX.
ay Of)
4) Increase generator output for 100 Watts RMS 72
volts across the 8-ohm load). Harmonic Dist~’ <7
Analyzer should measure 0.05 % distortion or “~~
5) Repeat steps 1 through 4 for RIGHT CHANNEL
BOTH CHANNELS DRIVEN
Connect 8-ohm load resistors across LEFT and RIGHT SPEAKERS SYSTEM-A terminals. Adjus‘
generator output and “VCLUME” control for 100 watts at Left and Right Channels (28.2 volts across
the 8-ohm loads). Harmonic Distortion Analyzer should measure 0.05 % distortion or less at each
Channel.
CAUTION . This precision high-fidelity instrument should be serviced only by qualified
* personnel, trained in the repair of transistor equipment and printed circuitry.