LC-46XL2E (serv.man4). Troubleshooting Table - Sharp TV Service Manual (repair manual). Page 19

LC-42XL2E/S/RU, LC-46XL2E/S/RU, LC-46X20E/S/RU, LC-52XL2E/S/RU, LC-52X20E/S/RU

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No picture appears on EXT1 - connected monitor during the tuner (U/V) reception.

                                            
Checklist:
1) Is the Signal Type (item) in MENU-Option-Input Select equal to Signal Type of an external device? 

⋅ ⋅ ⋅ Set it to “CVBS”, “Y/C” or “RGB”.

2) Is ANT-CABLE disconnected or connected improperly? 

⋅ ⋅ ⋅ Connect it correctly as per the operation manual.

3) The picture is sent to the monitor in a CVBS signal if the source during display is TV, CVBS or Y/C of EXT1-3.

When sent by component, etc., that signal is not sent to the monitor.

4) When the monitor picture is not sent and is not displayed on the monitor, refer to “No picture” for each terminal.
5) The video output from EXT1 is not the monitor output (output of the picture now watching).

The picture of the last selected TV channel is always sent to EXT1. (Specification)

TERMINAL UNIT:                 
Is CVBS signal output into pin (19) of SC502 (SCART1) from pin 
(2) of IC1501 (SW)?

YES

Check the setting of an external input device that connects of 
SC502.

NO

Is TUNRE_CVBS signal input into pin (6) of IC503 (SW)?

YES

Check the IC501 (SW), IC503 (SW) and their peripheral circuits.

NO

Is TUNRECVBS signal output from pin (17) of IC7504 (IF-
DEMO)?

YES

Check the line between IC7504 and IC503.
(Q7505, IC7508, etc.)

NO

Is IF signal output from pin (17) of TUNRE (TU7501)?

YES

Check the IC7504/FL7502 (VIF_SAW) and its peripheral circuits.

NO

Check whether I2C is normally accessed between TU7501 and 
IC7507 (COFDM).