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AUDIO TEST
Total Harmonic Distortion
Frequency Response
Power Bandwidth at Rated Distortion
(IHF Method)
Hum and Noise (Phono)
Range of Line Voltage and Frequency
Power Consumption - 117 v at 60 Hz (AC only)
EQUIPMENT
NEEDED
Audio Oscillator
VTVM
VOM
Oscilloscope
Load Box
Attenuator
Distortion Meter
Variac
AC Supply Fixture
Set Controls to the Following:
Input Selector
Stereo Switch
Tone Controls
Loudness
Stereo Bal. Sw.
Noise Filter
Speaker Switch
Power Switch
1.
Bias and Balance Settings and Voltage Checks
Turn unit on - watch carefully for any signs of voltage shorts.
(lK) still full ccw (from top of unit), check supply for 48 to 50.
pots for 0.8 mA current from each test point in the rear of the unit to ground.
Check power supply board
Check power supply board
2.
Sensitivity Check
Audio osc. to EXTRA at .3V (+2 dB) input.
taps.
Turn loudness pot to max., observe output of 18 watts (12V).
output jack with troubleshooting lead for same output as signal.
Distortion Check
3.
At 12V output max. distortion 0.6%.
4.
Tape Monitor Switch Check
Audio osc. to EXTRA at
speaker terminal.
output.
Connect input cable from L channel tape out to L channel tape in.
Note restoration of signal out.
tape monitor switch to out position.
Extra
Stereo
Flat "O"
Min.
Norm.
OUT
ON
OFF
.3 input to L channel.
Put tape monitor switch in the IN position.
Repeat process for R channel, then return
0.8%
18-25,000
25-20,000 Hz
-55
105-120v, 50-60 Hz
25-95 watts
for 25V +10%
for 12V +10%
Connect 8 ohm load to main speaker
Note output at left channel
2
±
1 db
With bias pots
Adjust bias
Check tape
Note loss of
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