Adjustment Procedures; Audio Circuit - Mitsubishi VS-60609 Service Manual

MODELS: VS-45609 / VS-50609 / VS-55609 / VS-60609 / VS-60719 / VS-70709

[Audio Circuit]

1. Input Level
Measuring
Oscilloscope
Instrument
TP14A, TP15A
Test Point
------
Ext. Trigger
Measuring
50mV/Div
Range
Input Signal RF Monaural
300 Hz modulation
Input Terminal
RF Input
[Audio Circuit]
2. Separation
Measuring
Oscilloscope
Instrument
TP14A, TP15A
Test Point
------
Ext. Trigger
Measuring
10mV/Div
Range
Input Signal
RF Stereo
RF Input
Input Terminal
Purpose: Set the input signal level to the MCS circuit.
Symptom: Distorted sound during a stereo broadcast.
1. Supply an RF monaural signal to the Ant A input, 300 Hz at 100% modulation
(25 kHz deviation).
2. Connect the oscilloscope to TP15A (Right Channel). (Junction of
R2K64 and R3A38)
3. Enter the Adjustment Mode and select the Audio Function.
4. Verify that the Audio Function items are set to the data values given the
table below.
5. Adjust Item "1 INP" for 1.55 ±0.06 Vp-p at TP15A.
6. Connect the oscilloscope to TP14A. (Junction of R2K62 and R3A15)
7. Confirm that the left channel output at TP14A is 1.55 ±0.06 Vp-p.
Note: Adjustment 2 (Stereo Separation) must be performed after this adjustment)
SERVICE MODE
Activate ........ MENU-0-1-5-7
Function .................AUDIO
Item No. .................VIDEO
Adjust Data ...........ADJUST
Save Data .... .........ENTER
Exit ..............MENU (twice)
Purpose: Adjust for optimum stereo separation.
Symptom: Poor stereo separation
Note: This adjustment must follow Adjustment 1 (Input Level)
1. Supply a RF Stereo Signal to the Ant. A input.
• Left Channel = 300 Hz modulation
• Right Channel = no modulation signal
2. Connect the oscilloscope to TP15A (right channel). (Junction of
R2K64 and R3A38)
3. Enter the Service Mode and select the Audio Function.
4. Adjust Item "3 WDE" for minimum signal at TP15A.
5. Change the modulation frequency to 3 kHz.
6. Adjust Item "4 SPC" for minimum signal at TP15A.
Activate ........ MENU-0-1-5-7
Function .................AUDIO
Item No. .................VIDEO
Adjust Data ...........ADJUST
Save Data .... .........ENTER
Exit ..............MENU (twice)
Page 28
AUDIO Function
SERVICE MODE
Item Abbrev. Data
1 INP 7
2 AUT 0
3 WDE 16
4 SPC 16
15 MZX 1
16 VZX 1
20 ATK 1