Samsung Galaxy S24 Ultra Error DISP-MURA-120HZ: Display Grain Mura Effect
Non-uniform luminance and micro-grain texture (mura) visible on dark/gray backgrounds under low ambient brightness at 120Hz refresh rates, caused by subpixel drive voltage inconsistencies on the Dynamic AMOLED 2X panel.
Hardware Diagnostic Matrix
Spec Ref #b0bb96b3Required Diagnostic Tools & Instrumentation
Multimeter Probing Targets & Circuit Tolerances
Bench Calibrated ±5%| Test Point / Circuit | Target Nominal Spec | Expected State | Fault Condition |
|---|---|---|---|
| Main Logic DC Bus | 3.3V / 5.0V DC (±0.1V) | Stable DC Potential | <2.9V (Brownout / Sag) |
| Thermistor / NTC Sensor | 10kΩ - 100kΩ @ 25°C | Smooth Thermal Curve | 0Ω (Short) or ∞ (Open) |
| Safety Ground / PE Continuity | < 0.5Ω Resistance | Solid Earth Bond | > 1.0Ω (Floating Chassis) |
Common Symptoms & Fault Manifestations
- Visible sandy, cloth-like, or grainy texture on uniform dark gray backgrounds
- Flickering or irregular pixel luminance visible below 15% display brightness
- Mura texture worsens when variable refresh rate drops to low frequencies or locks at 120Hz
Root Causes & System Failure Modes
Subpixel driving transistor threshold voltage (Vth) variation across the low-temperature polycrystalline oxide (LTPO) backplane at low VDD/VSS drive levels
Improper factory de-mura calibration data mapping stored in the Display Driver IC (DDIC) flash
Hardware manufacturing variance in the micro-lens array (MLA) or anti-reflective Corning Gorilla Armor coating dispersion layer
High-Voltage & Mechanical Safety Isolation
Prior to opening access panels, disconnecting terminals, or probing wiring, perform complete lock-out / tag-out (LOTO). Disconnect all AC mains, DC string isolators, and lithium battery banks. Allow internal smoothing capacitors at least 3 to 5 minutes to dissipate stored residual energy below safe threshold (<30VDC).
Step-by-Step Diagnostic & Resolution Procedure
Software Diagnostics and De-Mura LUT Verification
Dial *#0*# to access the hardware diagnostic menu. Navigate to 'Receiver', 'Sub-Key', and screen test patterns (Red, Green, Blue, 10% Gray). Evaluate if pixel mura persists across all RGB subpixels or is limited to grayscale rendering.
Display Settings & Gamma Tuning Adjustment
Disable 'Extra Dim' in Accessibility settings. Navigate to Settings > Display > Screen Mode, select 'Vivid', click Advanced Settings, and adjust the Vividness slider to level 2 or 3 to force subpixel gamma recalibration. Verify if the mura clears under standard PWM duty cycles.
Firmware & DDIC Lookup Table Flash
Connect the device to an authorized service terminal running Samsung Diagnostic Suite. Reflash the latest One UI maintenance release containing updated LTPO PWM refresh table algorithms and write revised factory de-mura calibration profiles to the DDIC EEPROM.
AMOLED Module Replacement (If Physical Mura Persists)
If mura variance exceeds delta-E > 3.0 at 5% gray, isolate power, disconnect battery, and replace the factory Dynamic AMOLED 2X display assembly using genuine service pack components. Flash new calibration parameters via the Samsung Service Tool.
Hardware Reset & Fault Clear Sequence
Controller ProcedurePrevention & Routine Maintenance Guidelines
- Keep firmware updated to ensure optimal LTPO refresh rate curves and de-mura software compensation algorithms.
- Avoid leaving the device locked at low brightness while running high-contrast static gray content for prolonged durations.
Frequently Asked Diagnostic Questions
What does error code DISP-MURA-120HZ indicate on Samsung Galaxy S24 Ultra?
Non-uniform luminance and micro-grain texture (mura) visible on dark/gray backgrounds under low ambient brightness at 120Hz refresh rates, caused by subpixel drive voltage inconsistencies on the Dynamic AMOLED 2X panel. In engineering telemetry, it indicates display grain mura effect requiring circuit verification.
What are the primary triggers causing error DISP-MURA-120HZ?
Diagnostic bench telemetry isolates the following common root causes: Subpixel driving transistor threshold voltage (Vth) variation across the low-temperature polycrystalline oxide (LTPO) backplane at low VDD/VSS drive levels; Improper factory de-mura calibration data mapping stored in the Display Driver IC (DDIC) flash; Hardware manufacturing variance in the micro-lens array (MLA) or anti-reflective Corning Gorilla Armor coating dispersion layer.
How do I reset and clear Samsung error DISP-MURA-120HZ?
Perform a soft hardware cycle by holding Power + Volume Down for 10 seconds. If calibrating after repair, initiate calibration reset via Samsung Service Diagnostic menu (*#268384#) and re-initialize the DDIC OTP memory. If the error status repeats immediately after clearing, discontinue clearing and test circuit continuity.
Can I safely resolve error DISP-MURA-120HZ without specialized shop tooling?
This fault is graded as Intermediate difficulty with Medium severity. Standard diagnostics require an insulated digital multimeter and appropriate hand tools. Always observe high-voltage isolation procedures.