Service manual

Page 41
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
To set the cutoff point for all three CRTs.
Monochrome has a color tint, or incorrect brightness.
[CRT Circuit]
7. CRT Cutoff
Oscilloscope
TP6R, TP6G, TP6B
------
50V/Div. 2msec/Div.
None
Video Input
Note: Use the Expand mode (full screen)
1. Select an External Input with no signal.
2. Enter the Adjustment Mode, VC Function.
3. Press “1”, automatically blanks the screen and sets COL to 0.
4. Set the data to the values given in the table below.
5. Connect the oscilloscope to TP6R.
6. Adjust the Red Screen VR so the black level is 180V, as shown below, or
186V ±1VDC using an DC Voltmeter.
7. Repeat Steps 4 and 5 to set the Blue and Green Screen VRs, using
TP6G and TP6B.
Note: White Balance must be performed after this adjustment.
DC ma meter
------
------
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NTSC White Raster
RF or Video
[CRT Circuit]
8. White Balance (NTSC)
To set the CRTs white level in the NTSC mode.
Monochrome has a color tint.
Note: Use the “FORMAT” button to activate the Expand mode (full screen).
1. Supply a full White Raster Signal
2. Activate the Service Mode, VC function.
3. Set the data for Item “23 COL” to 0.
4. Adjust Items “6 RDRH” and “8 BDRH” for optimum white at the center of
the screen.
5. Reduce the input luminance level to 25%.
6. Adjust Items “9 CTRH” and “11 CTBH” for optimum white.
7. Insert a Milliammeter in series with each CRT Cathode. The maximum
allowable current for each CRT is given in the table below.
8. Set the white raster to 100% and adjust Items “12 RDRL” and “13 BDRL” for
optimum white at the center of the screen.
9. Reduce the luminance level to 25%.
10. Adjust Item “14 CTRL” and “16 CTBL” for optimum white.
11. Set the data for Item “23 COL” back to 31.
Maximum CRT Current
CRT
55"& 65"
CURRENT
73"
CURRENT
RED 580 uA 900 uA
GREEN 580 uA 900 uA
BLUE 580 uA 900 uA
CIRCUIT ADJUST MODE
Activate …….. MENU-2-1-5-7
Function …...………..AUDIO
Item No. ……….…….VIDEO
Adjust Data ….…….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)
Item Abbr Data
1SCT42
2SBRT26
5SCON2
6 RDRH 30
7GDR35
8 BDRH 40
9 CRTH 25
10 CTGH 55
11 CTBH 20
Cutoff Preset VC Data