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ELECTRICAL MEASUREMENTS AND ADJUSTMENTS
Specification Measurement
The audio test CD 4822 397 30085 can be used to measure to the
specification.
Use to measure:
• Total Harmonic Distortion (THD).
• Intermodulation distortion.
• Signal-to-Noise Ratio (S/N)
A 7th order filter 4822 395 30204.
Changes to the transformer connections
If the appliance is to be connected to a mains voltage different from
that stated on the rating plate, the transformer connections must be
changed as shown in the figure.
Note
When changing to 110V or 127V, the glass fuse on the mains filter
must be changed from 160mA to 315mA.
Adjusting the offset control
(see SERVO PCB)
Put the servo-µp into service mode by simultaneously pressing the
power switch and the stop keys.
Connect a DC voltmeter between point 14 of IC6215 and ground.
With resistor 3315 regulate the voltage to 0V.
Control of the AGC and the offset circuits
(see SERVO PCB)
Play from test disc 4822 39730096 track 1. (CD without defects).
The voltage between point 14 of 106212 and ground should be
-4V ±2V.
The voltage between point 14 of IC6215 and ground must be
0V ± 5.5 V.
Adjusting the channel equality
(see DECODER PCB)
From the audio test CD, play the track or where the left and right
channels are modulated at 0dB.
Measure the output voltage of the left and right channels.
Adjust the output voltage of the left channel with bias resistor 3586
so that the difference with the right channel is 0dB ± 0.2dB
A DECODER with identification A05 and subsequent, this setting is
no longer valid.
Setting of the PLL circuit
(see DECODER PCB)
Put the device into the stop position.
Connect a frequency counter between point 22 of IC6501
(DEMOD) and ground.
Adjust the frequency with the coil 5501 to 4.350MHz ± 5kHz.
Note:
This installation must be done immediately after
switching on the device.
With decoding boards marked A05 and subsequent, this
setting is no longer valid.
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