Service manual

Page 38
Purpose:
Measuring
Instrument
Test Point
Measuring
Range
Input Signal
Ext. Trigger
Input Terminal
Symptom:
Purpose
Measuring
Instrument
Test Point
Measuring
Range
Input Signal
Ext. Trigger
Input Terminal
Symptom:
MODELS: WS-48511 / WS-55511 / WS-55711 / WS-65511 / WS-65611 / WS-65711 / WS-65712 / WS-73711 / WS-B55
Oscilloscope
Connector ST pins 16&12
------
50mV/Div
RF Stereo
300 Hz modulation
RF Input
Check the input signal level to the MCS circuit
Distorted sound during a stereo broadcast.
1. Supply an RF MCS signal to the Ant A input, 300 Hz at 100% modulation
(25 kHz deviation) for right and left channels.
2. Connect the oscilloscope to connector ST pin 16 (Right Audio).
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. Set the data for Item “1 INP” for 1.56 Vp-p ±0.06V. (550mv ±10mv rms)
6. Connect the oscilloscope to connector ST pin 12 (Left Audio).
7. Confirm that the left audio level at pin 12 of the ST connector is 1.56 Vp-p
±0.06V (550mv ±20mv rms).
Note: Adjustment 2 (Stereo Separation) must be performed after this adjustment)
[Audio Circuit]
1. MCS Input Level
Oscilloscope
Conector ST pin 16
------
10mV/Div
RF Stereo
RF Input
[Audio Circuit]
2. Separation
Check stereo separation
Poor stereo separation
Note: This adjustment must follow Adjustment 1 (Input Level)
1. Supply a RF Stereo Signal (dual tone stereo) to the Ant. A input.
• Left Channel = 300 Hz modulation
• Right Channel = no modulation
2. Connect the oscilloscope to connector ST pin 16 (Right Audio).
3. Enter the Adjustment Mode and select the Audio Function.
4. Set the data for Item “3 WDE” for minimum 300 Hz signal.
5. Change the modulation frequency to 3kHz.
6. Adjust the data for Item “4 SPC” for minimum 3kHz signal.
AUDIO Function
Item # Abbrev. Data
1INP8
3WDE3
4SPC3
CIRCUIT ADJUST MODE
Activa te …….. MENU-2-1-5-7
Function …...………..AUDIO
Item No. ……….…….VIDEO
Adju s t Da ta ….…….ADJUST
Save Data …. ………ENTER
Exit …………..MENU (twice)
CIRCUIT ADJUST MODE
Activate …….. MENU-2-1-5-7
Function …...………..AUDIO
Item No. ……….…….VIDEO
Adjust Data ….…….ADJUST
Save Data …. ………ENTER
Exit …………..MENU (twice)