Sharp VL-MC500U Service Manual page 30

VL-MC500U/K
ADJUSTING THE LCD CIRCUIT
* To make this adjustment, set the backlight switch to the "NORMAL" position.
(Wiring board diagram: Main Side A)
C420
C419 R418 C418 TL4429 TL418
L471
X401
C473 C472
R2851
TL2824
C2828
D471
C2822
04
R407
3301
L2803
C2826 R2856 C2823
R2840
R2804
R2805 C2802
D2801
TL2800
COMMON PULSE
1. DAC full-scale adjustment
Test point TL7824(G OUT)
Address VCR ADJ 5DF(G)
Mode VCR AV input
Procedure 1) Set the data of the addresses 582/585/59A/5E1 to FF/80/77/00, respectively. (At this time, the LCD is not
displayed.)
2) Set the data of the addresses 595/5D0/5D3 to 00/80/48, respectively.
3) Connect a digital voltmeter to TL7824(G_OUT) to measure the DC voltage.
* The voltage value at this time is regarded as (DA_VG).
4) Set the data of the addresses 595/5D0 to 80/00, respectively.
5) Adjust the DC voltage to the adjustment standard value at the address 5DF.
6) Preset the same data as the address 5DF to 5DE/5E0.
7) Restore the data of the addresses 582/585/595/59A/5D0/5D3/5E1. (Initial values: 40/C5/28/7F/28/40/71)
DA_VG+0.55V ± 10mV
Adjustment
rating
Examples • During IC705 replacement.
2. COMMON PULSE adjustment
Test point TL2801(C OUT)
Mode VCR AV input
Procedure 1) Connect TL2800 to GND.
2) With VCR ADJ 32, adjust the output voltage of TL2801 and the DC voltage value of the digital voltmeter to the
specified adjustment values.
7.05V ± 50mV
Adjustment
rating
Examples • During IC705 replacement.
3. COM-BIAS adjustment
Test point LCD panel display surface
Mode VCR AV input
Procedure 1) Input the white 100% signal to AV input.
2) Set up the illuminance meter (TOPCON IM-3) on the LCD panel surface. (The outside light must not enter.)
3) Minimize the ripple of the output waveform of the illuminance meter.
Adjustment Minimum
rating
Remark Make this adjustment after 5-minute or longer aging.
Examples • During LCD Panel replacement. • During IC705 replacement.
C2805
C2808 R2806
C421 C410
C475 R431 FB456
R432 C476
R2852
TL2825 TL2826 R2853
C2824
C2810
C2825
R2823
SC2801
C2811
R2825
C2812
R2830
C2814
C2816
TL2836
TL2835 C2813
IC2803
R2812 R2802
R2819 R2820 R2829
D2800 D2802
TL2800
TL2801 C2803
Q2800
TL2801(C OUT)
COMMON PULSE
• During VIO ENG (IC4401) replacement.
(Wiring board diagram: Main Side B)
R7835 R7823
R7840 R7824
C7821
R7836 C7830
C7820
C7827
TL7824(G OUT)
R7837
DAC full-scale
IC7801
IC7802
C7802 C7804
C7826 C7824
L1431
C1440
Adjustment procedure and connecting same as the VCR section.
Address VCR ADJ 32(C)
Address VCR ADJ 33
Response time : 0.6sec
30
TL4437
TL4440
TL234 TL4439
R4454 C4454
C4427 R4456
R7820 R7822
TL7820
C7807
C7801 C7809
C7805 C7808
R7829 C7803
TL7825
IC4401
R7826
TL7823
TL7824
C7806
C7823
C1438
TL1431 R1442
TL4428 TL4405 TL4426
R4488
Q
C4485 R4486
Q4481
R4489
R4472 R4471
R1405
C4482
R4485
Q1404
C1436
C1432
R1432
C1410
Q1432