4 Troubleshooting
Notes: 1. Before troubleshooting, setup the PC’s display as below.
• Resolution: 1024 x 768
• H-frequency: 48 kHz
• V-frequency: 60 Hz
2. If no picture appears, make sure the power cord is correctly connected.
3. Check the following circuits.
• No raster appears: Audio PCB, SMPS PCB, Main PCB
• 12V develop but no screen: Main PCB
• 12V does not develop: Audio PCB, SMPS PCB
4. If you push and hold the “EXIT” button for more than 5 seconds, the monitor automatically turns back
to the factory preset.
4-1 No Power (GH15LS/GH15ES/GH15MS)
Does proper DC 12 V
appear at FT901, FT902
or Pin 1, 2 of CN101?
Yes
Does proper DC 3.3 V
appear at Pin 7 of CN 101?
Yes
Check IC102 and Q192.
No
Check SMPS or CN101.
No
Check SMPS.
GH15LS/GH15ES/GH15MS 4-1
4 Troubleshooting
4-2 No Video
Does the H-sync pulse
1
appear at Pin 9 of IC108?
Yes
Does the H-sync pulse
4
appear at Pin 150 of IC105?
Yes
Does the V-sync pulse
2
appeaer at Pin 30 of IC301?
Yes
Does the V-sync pulse
3
appeaer at Pin 148 of IC105?
Yes
No
No
No
No
Check CN102.
Replace IC108 or
check its related circuit.
check CN102.
Replace IC301 or
check its related circuit.
Does the clock pulse
5
appeaer at Pin 44 of IC105?
Yes
Do the pulse appeaer
6
at Pin 43 of IC105?
Yes
Does the waveforms
7
appeaer at Pin 3
and 16 of CN201?
Yes
Replace LCD Panel
No
No
Replace IC105 or
check its related circuit.
No
Replace IC251 or
check its related circuit.
4-2 GH15LS/GH15ES/GH15MS
WAVEFORMS
1 5
4 Troubleshooting
2
3
6
7
4
GH15LS/GH15ES/GH15MS 4-3
4 Troubleshooting
4-3 User Controls Don’t Work
Does the DC level change at
Pin 35 and 36 of IC301 when you
push the front panel button?
Yes
Refer to 4-4 No OSD Display.
4-4 No OSD
There is video but no OSD.
While pushing a front control button does
5
any pulse appear at Pin 46,47
and 55, 56 and 63,64 of IC105?
Yes
Replace IC105.
No
No
Check the buttons.
(SW801~SW808)
3
1
Do sync signals appear at Pin 44,
150 and 43 of IC105?
Replace IC105 or check its
related circuit.
2
Yes
No
Replace IC251 and IC252.
Replace CN251.
WAVEFORMS
5
Replace IC105 or check
its related circuit.
4-4 GH15LS/GH15ES/GH15MS
4-5 No SOUND (GH15MS)
4 Troubleshooting
Does the DC 12V appear
at Pin 15, 16 of IC401 and
Pin 5, 6, 7, 8 of Q403?
Yes
Does the sound input signal
appear at Pin 4 and 9 of IC401?
Yes
Does the sound signal appear at
Pin 14 and 17 of IC401?
Yes
Check CN402 outputs.
No
No
No
Check Q403, Q401 and related circuit.
Check CN401
and related circuit.
Check IC401 and related circuit.
GH15LS/GH15ES/GH15MS 4-5
4 Troubleshooting
4-6 Microphones Don’t Work
Does the PC’s sound
program operate well?
Yes
Is the connection between the PC
and monitor secure?
Yes
Is the Internal Microphone
connector attached?
Yes
Does the Internal Microphone
work?
Yes
No
No
No
No
Check the PC’s sound program
and compatibility.
Connect the cable between the PC
and monitor.
Check the connection between
CN808 on the Audio PCB and the
Internal Microphone.
Check Q801 and related circuits.
Does the External Microphone
work?
Yes
OK
4-7 Headphones Don’t Work
Can you hear any sound from
the Headphones?
Yes
OK
No
No
Check the CN803 jack.
Check CN802 on the Audio PCB
and related circuit D805, D806,
R811, and R812.
4-6 GH15LS/GH15ES/GH15MS
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