Samsung SyncMaster LD190G, Service Manual

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4-7
4. Troubleshooting
4-4. No Video (USB Input)
Symptom - Even though the LED power turns on, the screen is blank when the USB cable is connected.
Major checkpoints
- Check the USB cable connections.
- Check whether the USB driver is installed onto the PC correctly.
- Check whether the USB display device is recognized correctly after connecting the USB cable.
- Check whether the LVDS cable is connected to the panel correctly.
- Check whether the lamp connector of the panel is connected correctly to the IP board.
Diagnostics
⑤
Main Board Front
②
①
③
④
②
Yes
Check the USB cable and its
connections
Yes
Check whether the USB driver
is installed on the PC and
the DL-120 (IC301) driver is
installed on the EEPROM
(IC302) correctly (see also
UBIsync Restrictions).
No
Check whether the PC has
recognized the USB display correctly
(using the Device Manager).
Are X202 and X301 oscillating
correctly?
Check the circuits related to
X202 and X301.
No
Yes
Do the IC301 DVI_D (0:11)
outputs appear correctly?
Check and replace the circuits
related to DL-160.
No
Yes
Do the TMDS outputs appear at
pins 21 to 32 of IC303?
Check and replace the circuits
related to IC303.
No
Yes
Do output signals appear at pins 8
to 16 and 18 to 30 of CN202?
①
②
Check the circuits related to
IC201 and CN202.
No
③
④
⑤
Caution Make sure to disconnect the power before working on the IP board.