Horizontal Centering; Mts Circuit Adjustment - Hitachi 27UX01B-501 Service Manual

Service Adjustments (Electronic Controls, cont.)

Horizontal Centering

Serviceman DAC Adjustment (D0)
Preparation:
Connect a crosshatch generator.
Procedure:
1. In the Serviceman Mode for making electronic
adjustments. Select the Horizontal Centering
Adjustment DAC (D0) and adjust until the center of
the crosshatch pattern is centered on CRT.
2. EXIT the Serviceman Adjustment Mode.
MTS Circuit Adjustments
The MTS Circuit Adjustments require two steps:
1. Input Level Adjustment.
2. Stereo Separation Adjustment.
Input Level Adjustment (M0)
Preparation:
1. Connect an RMS meter with filter jig as shown in
Fig. 23.
RMS
METER
4700p
Figure 23. Filter Jig
2. Connect an RF signal generator to the RF
antenna input.
Procedure:
1. Apply the following signal from the RF signal
generator:
Video: 100 IRE flat field, 30% modulation.
Audio: 300Hz, 100%
(70 ±5dB, 75 OPEN, P/S 10dB).
2. Adjust the MTS Input Level Adjustment (M0) until
the voltage measured is 106 ± 6.0mV rms.
TPE11
10k
modulation, monaural
Stereo Separation Adjustment (M1 & M2)
Preparation:
1. Connect an RF signal generator to the RF antenna
input.
2. Connect a scope to TPE10.
Procedure:
1. Select Stereo Mode in Audio menu
2. Apply the following signal from the RF signal
generator:
Video: 100 IRE flat field, 30% modulation.
Audio: 300Hz, 100% modulation, stereo (left only)
(70 ±5dB, 75 OPEN, P/S 10dB).
3. Adjust the MTS Low-Level Separation Adjustment
(M1) until the amplitude displayed on the scope
is minimum.
4. Apply the following
signal generator:
Video: 100 IRE flat field, 30% modulation.
Audio: 3KHz, 100% modulation, stereo (left only)
(70 ±5dB, 75 OPEN, P/S 10dB).
5. Adjust the MTS High-Level Separation Adjustment
(M2) until the amplitude displayed on the scope is
minimum.
6. Repeat above steps 2 through 5 until the amplitude
is at minimum for both signals.
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signal from the RF