Troubleshooting Guide Hardware & T-Con Diagnosis

Panel Test for Half-Screen Fault – Android Smart TV Troubleshooting

Technician-verified diagnosis, root causes, software repair workflows, and USB firmware solutions.

⚡ Quick Answer

To execute Panel Test for Half-Screen Fault, utilize a digital multimeter to measure critical DC power rails (VIN 12V, VGH +30V, VGL -6V, AVDD +16V), inspect chip-on-film (COF) thermal signatures, and identify physical board silkscreen part numbers for accurate replacement.

Common Symptoms

Complete loss of picture with functional backlight and normal sound output.
Half of the screen displays lines, slow motion, or dark ghosting.
T-Con DC-DC converter IC becomes excessively hot within seconds of powering on.
Micro-short on panel bypass ceramic capacitors pulling mainboard supply rails low.

Root Causes

Blown surface-mount fuse (F1) on the T-Con board.
Failed DC-DC power management IC (e.g. TPS65178, SM4186) failing to generate gate drive rails.
Short-circuited MLCC bypass capacitor on the source driver PCB.
Internal gate line leakage inside the liquid crystal panel glass.

Step-by-Step Diagnostic & Repair Steps

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Identify Silkscreen Number: Locate the white printed engineering model on the T-Con board (e.g., 6870C-0532A, HV320WHB-N86) or mainboard.
Measure Primary Rail: Check 12V supply at fuse F1 relative to chassis ground. If 12V is missing, the fault is on the mainboard panel power switch circuit.
Verify Gate Voltages: Measure VGH test point (+25V to +32V DC) and VGL test point (-5V to -8V DC). If voltages pulse briefly and drop to 0V, the protection circuit has tripped due to a panel short.
Tape Cut Isolation Technique: For internal panel shorts, place narrow kapton tape over clock (CKV/STVP) lines on the T-Con ribbon to isolate the damaged gate drivers.
Replace Defective Module: If voltages remain missing with panel ribbons disconnected, replace the T-Con board.

When is Firmware Flashing Required?

Hardware diagnostics distinguish between electronic board failures and software issues. If voltages are verified normal but the display renders noise or wrong resolution, flashing the correct panel profile firmware resolves the defect.

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