Samsung Galaxy S24 Ultra Error DISP-MURA-PWM120: Display Grain Mura Effect
Low-luminance display non-uniformity (mura effect) on the Dynamic AMOLED 2X panel caused by subpixel luminance variance at 492 Hz PWM dimming thresholds coupled with anti-reflective glass refraction.
Hardware Diagnostic Matrix
Spec Ref #851e59ddRequired 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
- Fine paper-like grain texture visible across dark gray backgrounds at under 10% brightness
- Horizontal or diagonal microscopic banding during 120Hz dynamic refresh switching
- Uneven pixel luminance decay in low-light dark mode environments
Root Causes & System Failure Modes
Subpixel drive voltage imbalance (ELVDD/ELVSS delta variance) across the LTPS/LTPO TFT backplane at ultra-low duty cycles
Optical scattering artifacts introduced by the Corning Gorilla Armor low-reflection coating over low-luminance subpixel clusters
Improper factory de-mura Look-Up Table (LUT) calibration stored within DDI (Display Driver IC) EEPROM
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
Diagnostic Mode Hardware Verification
Open the Phone dialer and enter *#0*#. Navigate to the Sub-Pixel & Gray Gradient test patterns (specifically 5%, 10%, and 15% Gray). Verify if the grain artifact is static hardware mura across the TFT matrix or an image rendering artifact.
Software Color Profile & PWM Mitigation
Navigate to Settings > Display > Screen Mode. Select 'Vivid' and access Advanced Settings. Adjust the 'Vividness' slider to level 2 or 3 to force subpixel voltage saturation. Disable 'Extra Dim' in Accessibility to prevent the PWM duty cycle from dropping below stable threshold currents.
DDI Gamma Calibration Refresh via Firmware
Reflash the latest official One UI binary using Samsung Odin with CSC (not HOME_CSC) to clear system cache, reinitialize Display Driver IC (DDI) LUT registers, and load updated dynamic PWM frequency tables.
OCTA Display Panel Replacement
If mura variance exceeds delta E > 3.0 at 5 nits after software calibration, replace the Dynamic AMOLED 2X assembly (OCTA panel with integrated DDI). Ensure recalibration using Samsung Authorized Service Repair Software (ASR) to write factory optical LUT parameters.
Hardware Reset & Fault Clear Sequence
Controller ProcedurePrevention & Routine Maintenance Guidelines
- Avoid running continuous zero-percent brightness levels with Extra Dim mode enabled
- Keep One UI firmware updated to ensure optimal LTPO dynamic variable refresh rate and PWM tuning algorithms are applied
Frequently Asked Diagnostic Questions
What does error code DISP-MURA-PWM120 indicate on Samsung Galaxy S24 Ultra?
Low-luminance display non-uniformity (mura effect) on the Dynamic AMOLED 2X panel caused by subpixel luminance variance at 492 Hz PWM dimming thresholds coupled with anti-reflective glass refraction. In engineering telemetry, it indicates display grain mura effect requiring circuit verification.
What are the primary triggers causing error DISP-MURA-PWM120?
Diagnostic bench telemetry isolates the following common root causes: Subpixel drive voltage imbalance (ELVDD/ELVSS delta variance) across the LTPS/LTPO TFT backplane at ultra-low duty cycles; Optical scattering artifacts introduced by the Corning Gorilla Armor low-reflection coating over low-luminance subpixel clusters; Improper factory de-mura Look-Up Table (LUT) calibration stored within DDI (Display Driver IC) EEPROM.
How do I reset and clear Samsung error DISP-MURA-PWM120?
Perform a hardware recovery cache wipe: Power off device, connect via USB-C to PC, hold Volume Up + Power until Recovery Menu appears, select 'Wipe cache partition', confirm, and reboot system. If the error status repeats immediately after clearing, discontinue clearing and test circuit continuity.
Can I safely resolve error DISP-MURA-PWM120 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.