6 components coveredField manual · TV
LG NanoCell (NANO75 etc.) and UHD UQ series (UQ7070 / UQ7570 / UQ8000): quick sheet
Covers: LG 4K LED-LCD sets on webOS: NanoCell NANO75/NANO80-class (2021-2023) and UHD UQ7070, UQ7570, UQ8000 (2022) and their UP/UR siblings. Not LG OLED (see the OLED quick sheet).
LG's volume LCD lines. Both use the same basic layout: power board, webOS main board, T-con and direct-lit LED strips. NanoCell adds a particle filter layer for color and, per retailer specs, a 10-bit panel; the UQ is 8-bit. The workhorse repair is direct-lit LED strip replacement: many sizes use 5-22 strips depending on size.
Safety first
- Discharge time: unplug and wait several minutes before touching the power board.
- Live backlight and power-board tests are caution work with insulated probes.
- Two people to lift the bare panel; it breaks from flexing.
How it works
Power board feeds standby and main rails and the LED drive; the main board runs webOS and enables the backlight once it has booted and recognized the panel.
The backlight is a set of LED strips behind a diffuser and lens array. LEDs are wired in series strings, so one open LED blacks out the whole string or the whole backlight.
NanoCell models commonly use IPS-type panels (wider viewing angle, lower native contrast than VA); this is normal and not a fault when customers compare to a VA set.
webOS has a built-in Screen Self-Diagnosis (2021+: All Settings > Support > Screen Self-Diagnosis; 2020: Support > Additional Settings > Picture Test; older: Picture > Picture Test) that separates panel faults from source faults.
Components & tests
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Always confirm values against the tech sheet for the exact model.
OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Flat-panel TV mounted on a living room wall with the screen off by Daria Klet, Pexels License
