Sharp LL-T1815 Service Manual ▷ View online
PC-UM10M
LL-T1815-H/B TROUBLE SHOOTING
4 – 5
THE PC DISPLAY DOES NOT WORK. (DIGITAL DVI)
THE FIRMWARE CANNOT BE UPGRADED
AUDIO DOES NOT SOUND
Does the display work normally with analog inputs?
3
(No)
First, check with analog inputs.
4
(Yes)
Is 14Pin of CN2 at DC+5V?
3
(No)
Check CN2 and the signal source.
4
(Yes)
Are the signal levels of 1PIN, 2PIN, 9PIN, 10PIN,
17PIN, 18PIN, 23PIN, and 24PIN of CN2 changed?
3
(Yes)
IIC8 abnormality
4
(No)
Are the waveforms at 1PIN and 2PIN of IC7
changed normally when the resolution is changed?
3
(No)
Check IC7 peripheral circuits.
4
(Yes)
Check IC7and IC8.
Connected to the analog input CN1?
3
(No)
Connect the jig fro rewriting the firmware to the
analog input CN1.
4
(Yes)
Is SW1 set to 1, 2 side? (CN1 side when viewed
from you)
3
(No)
Set SW1 to 1, 2 side (CN1 side when viewed from
you).
4
(Yes)
Is 2PIN of Q16 at the GND level?
3
(No)
Check SW1 and R258.
4
(Yes)
Are 1PIN and 13PIN of IC6 changed normally?
3
(No)
Check IC6 peripheral circuits.
4
(Yes)
Are signal waveforms provided at 12PIN - 19PIN
of IC18?
3
(No)
ICheck IC18 and IC19 peripheral circuits.
4
(Yes)
Check 31, 32, 33, 35, and 44PIN of IC15. (If there
is no abnormality, IC15 or IC19 is defective.)
Is the audio cable connected to CN2 of the
AUDIO PWB?
3
(No)
Connect the audio cable to CN2 of the AUDIO
PWB.
4
(Yes)
Is 1PIN of CN1 at DC+12V?
3
(No)
Check Q15 of the main PWB and the AU12V
power line.
4
(Yes)
Is the voltage at 2PIN of CN1 changed by varying
the sound volume?
3
(No)
Check IC15 and its peripheral circuits.
4
(Yes)
Are 3PIN and 4PIN of CN1 changed to the GND
level when any display is made?
3
(No)
Check IC20 and its peripheral circuits.
4
(Yes)
Is 5PIN of CN1 at the GND level?
3
(No)
Check CN1, the cable connected to CN1, and
CN3 of the main PWB.
4
(Yes)
Replace the AUDIO PWB.
PC-UM10M
LL-T1815-H/B WAVE FORM
5 – 1
CHAPTER 5. WAVE FORM
Waveform measurement condition: Input each of the display patterns and measure the waveform (timing chart)
CAUTION
Probe: Tectronix TDS64BB
Reception mode: VESA 1280 X 1024
Reception mode: VESA 1280 X 1024
H: 80kHz V: 75Hz DOTCLK: 135MHz
WAVEFORM FIGURE
WAVE FORM1 : XN1(
IC16’s 21PIN
)
Frequency:
24MHz
Display screen: Arbitrary
2V/DIV, 25ns/DIV
WAVE FORM2 : XIN2(
X1's PIN on C113 side
)
Frequency:
24MHz
Display screen: Arbitrary
2V/DIV, 25ns/DIV
WAVE FORM3 : VSYNC (LD12)
Frequency:
75MHz
Display screen: Arbitrary
2V/DIV, 2.5ms/DIV
Wave-form No.
Measurement point
Name of waveform
Display pattern
1
IC16’s 21PIN
XIN1
Arbitrary
2
X1's PIN on C113 side
XIN2
Arbitrary
3
LD12
VSYNC
Arbitrary
4
LD11
HSYNC
Arbitrary
5
LD20
LCD CLK
Arbitrary
6
LD21
LCD DE
Arbitrary
7
IC23's 29, 30, 41, 42PIN
LVDS CK
Arbitrary
8
RN1 - RN12
LCD DATA
Pattern in every 2 lines of black and white
9
RN1 - RN12
LCD DATA
Pattern in every 2 lines of black and white
10
IC8 side of C7, C11, C15
RGB OUT
16 monochromatic gradation patterns
11
IC10/11/12's 2, 3, 5, 6, 8, 9, 11, 12, 39, 40, 42,
43, 45, 46, 48, 49PIN
43, 45, 46, 48, 49PIN
SDRAM I/O DATA
Pattern in every 2 lines of black and white
12
IC10/11/12's 2, 3, 5, 6, 8, 9, 11, 12, 39, 40, 42,
43, 45, 46, 48, 49PIN
43, 45, 46, 48, 49PIN
SDRAM I/O DATA
Pattern in every 2 lines of black and white
Oscilloscope: Tectronix TDS64BB
Input signal:
VESA 1280 X 1024
H: 80kHz V: 75Hz
DOTCLK: 135MHz
GND
GND
GND
PC-UM10M
LL-T1815-H/B WAVE FORM
5 – 2
WAVE FORM4 : HSYNC (LD11)
Frequency:
80kHz
Display screen: Arbitrary
2V/DIV, 5
µ
s/DIV
WAVE FORM5 : LCD CLK (LD20)
Frequency:
54MHz
Display screen: Arbitrary
2V/DIV, 10ns/DIV
WAVE FORM6 : LCD DE (LD21)
Frequency:
64Hz
Display screen: Arbitrary
2V/DIV, 5
µ
s/DIV
WAVE FORM7 : LVDS CK (
IC23's 29, 30, 41, 42PIN
)
Frequency:
54kHz
Display screen: Arbitrary
500mV/DIV, 10ns/DIV
WAVE FORM8 : LCD DATA (RN1 - RN12)
Display screen: Pattern in every 2 lines of black and
white
2V/DIV, 4
µ
s/DIV
GND
GND
GND
GND
GND
GND
WAVE FORM9 : LCD DATA(RN1 - RN12)
Display screen: Pattern in every 2 lines of
black and white
2V/DIV, 20ns/DIV
Enlarged
PC-UM10M
LL-T1815-H/B WAVE FORM
5 – 3
WAVE FORM10 :RGB OUT (
IC8 side of C7, C11, C15
)
Display screen: 16 monochromatic gradation patterns
500mV/DIV, 4
µ
s/DIV
WAVE FORM11 :
SDRAM I/O DATA
(
IC10/11/12's 2, 3, 5, 6, 8, 9, 11, 12, 39,
40, 42, 43, 45, 46, 48, 49PIN
)
Display screen: 16 monochromatic gradation patterns
51V/DIV, 2
µ
s/DIV
GND
GND
GND
WAVE FORM11 :
SDRAM I/O DATA
(
IC10/11/12's 2, 3, 5, 6, 8, 9, 11, 12, 39, 40
42, 43, 45, 46, 48, 49PIN
)
Display screen: Pattern in every 2 lines of black an
white
1V/DIV, 50ns/DIV
Enlarged
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