Service manual
14
14GT15
14GT20
CUT-OFF, BACKGROUND AND SUB-CONTRAST ADJUSTMENT
No. Adjusting point Adjusting procedure/conditions Waveform and others
CRT CUTOFF
ADJUSTMENT
(I
2
C BUS
CONTROL)
1. Switch TV to VIDEO mode,BLUE BACK OFF, with
NO VIDEO signal.
2. Press R/C to set Picture Normal condition.
3. Connect the oscilloscope to Red OUT from
IC801.(TP851)
Range : 1 V/Div (DC)
Sweep : 5 msec/Div
4. Adjust SCREEN VR ,so that the tip of signal reach
3.0 Vdc + 0.1 Vdc.
1
1 V
3.0Vdc
0
SUB-BRIGHT-
NESS
ADJUSMENT
(I
2
C BUS
CONTROL)
1. Call " SUB-BRI" in service mode. (Receive Cross-
hatch pattern with 5 black level windows)
2. Adjust the " SUB BRIGHT " bus data in order that
the line 1, 2 and 3 have the same darkness
whereas line 4 is slightly brighter than line 1, 2
and 3 and finally line 5 will be the brighter than
line 4.
2
1, 2, 3 are in same black level.
1 2 3 4 5
WHITE BAL-
ANCE SERV-
ICE MODE
ADJ. (I
2
C BUS
CONTROL)
1. Receive the "WHITE" pattern with BURST signal.
2. Press R/C to set Picture NORMAL condition.
3. Connect the DC miliammeter between TP602 (-)
and TP603 (+).
4. Check Beam current should be around 800 µA.
5. Set it to service mode and adjust the " WPG"
(WhitePoint-G), "WPB" (White Point-B) data to
have a colour temperature of 12,300°K ( white ).
* Note .
6. Receive "WHITE" pattern, with BURST signal, and
set Brightness Y by generator, to **10cd/m
2
Minolta CA-100) by reducing Luminate Y signal.
7. Adjust "CUT-R" & "CUT-G" to get 12,300°K . Then
go back normal mode. (High Bright)** to check
colour temperature. If out of range, back to 1.
Note: This adjustment must be done after
warming up the unit for 30 minutes or
longer with a beam current over 500µA).
* Adjust DRI-GC/GW, DRI-BC/BW as following
data, after finishing DRI-GS and DRI-BS: DRI-
GC=DRI-GW="DRI-GS"-7:DRI-BW="DRI-BS"-
7:DRI-RC=25:DRI-BC=DRI-BS:DRI-RW=32
** Low=10cd/m
2
:High=200cd/m
2
3 * 12300°K X : 0.272
Y : 0.275
(MINOLTA COLOUR ANALYZER
CA-100)
*Note: Above Data can be UP/
DOWN by Volume key.
Maximum
beam check
1. Receive the "Monoscope Pattern" signal.
2. Press R/C to set Picture NORMAL condition.
3. Connect the DC miliammeter between TP603 (+)
and TP602 (–).
(Full Scale: 3 mA Range)
4. Beam current must be within 800 ± 100 µA.
4