Sharp 20LK32, Service Manual

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12
20LK32
20LK62
CRT 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.(TP47R)
Range : 1 V/Div (DC)
Sweep : 5 msec/Div
4. Adjust SCREEN VR ,so that the tip of signal reach
3.5 Vdc + 0.1 Vdc.
1
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 990 ± 50 µA.
4
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
wherelse 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.
WHITE BAL-
ANCE SERV-
ICE MODE
ADJ. (I2C BUS
CONTROL) 3 # 11,600° K X : 0.273
Y : 0.280
( MINOLTA COLOUR ANALYZER
CA-100)
*NOTE: Above DATA can be UP/
DOWN by volume key.
LOW HIGH
20" 1.8cd/m
2
115cd/m
2
* 11,600° K
DRI-GW="DRI-GS"DATA-5
DRI-BW="DRI-BS" DATA-5
1. Receive the "Monoscope Pattern" signal.
2. Press R/C to set Picture NORMAL condition.
3. Connect the DC miliammeter between the TP 602
( - ) TP 603 ( + ).
4. Check Beam current should be around (990µA)
5. Set it to service mode and adjust the DRI-G-MH,
& DRI-B-MH data to have a colour temperature
of 11,600°K ( white ).
6. Receive "WHITE" pattern, WITH BURST signal,
and set BRIGHTNESS Y by generator, to ** 10
cd/m2 (MINOLTA CA-100) by reducing LUMINATE
Y signal.
7. Adjust "CUT-R" & "CUT-G" to get 11,600°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.
DRI-R-MH=32 (FIXED)
DRI-G-MH=33 (FIXED)
DRI-B-MH=37 (FIXED)
DRI-R-MH=32 (FIXED)
1 2 3 4 5
1 V
3.5Vdc
0