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<mark>3.</mark> If D2 fails to light up and there’s no HDMI output after power-on, the possible causes are:
(1)Incorrect single/dual-channel configuration (R20);
(2)Mismatched LVDS wire sequence;
(3)Short-circuit R21 and retest (for VESA/JEIDA mapping);
(4)Differential pair polarity (+/−) reversed (Fix: First swap only O2+/O2− and OCLK+/OCLK−. If D2 lights up after swapping, polarity is correct; then swap all remaining twisted pairs).
'''Double-check to ensure correct wiring and configurations.'''
'''If the debug print scrolls continuously, the cause is definitely unstable LVDS signals''', resulting in changes to the 5 parameters shown above:
(1)Ensure LVDS differential pairs use twisted pairs and are free from interference.
(2)If InputPclk fluctuates, check if SSC (Spread Spectrum Clocking) is enabled; disable it for testing if possible.
(3)If HTotal or VTotal fluctuates, check the synchronization mode in software settings (usually Freerun or FrameLock). For LVDS-to-HDMI output, the mode must be Freerun with fixed HTotal/VTotal. For direct LVDS display, HTotal/VTotal may vary within a limited range without affecting the image. Thus, LVDS working for direct display does not guarantee valid LVDS-to-HDMI output.