LCD TV with the panel removed, showing the grid of lit LED backlights
7 components covered

Field manual · TV

Samsung Neo QLED QN85 / QN90 Mini-LED (B / C / D, 2022-2024): quick sheet

Covers: Samsung Neo QLED 4K mini-LED sets: QN90B/QN90C/QN90D and QN85B/QN85C/QN85D, e.g. QN65QN90CAFXZA, QN65QN90DAFXZA, QN55QN85DBFXZA. Year letter: B = 2022, C = 2023, D = 2024. QN90C sizes 43-85 in; QN90D 43-98 in; QN85C 43-85 in; QN85D 55-85 in. QN90DD / QN90CD are retailer variants of the same series (check the exact suffix before ordering parts).

Cross-checkedBrands: Samsung7 components

Samsung's mid-range mini-LED line: thousands of small LEDs grouped into local-dimming zones, a quantum-dot LCD, four HDMI 2.1-class inputs and Tizen. The QN90 adds an anti-glare layer and higher brightness; the QN85 is the cheaper step down. Panel type changes by size (VA on some, wide-angle ADS-type on others), so viewing-angle complaints need the exact size.

Safety first

  • Unplug and wait before opening.
  • Power-board and LED-driver live tests are caution work.
  • Two people to move or lift the panel; mini-LED boards and films scratch easily.

How it works

The power board supplies standby, logic and LED drive rails. A dimming controller on the main board tells the mini-LED driver how bright each zone should be, frame by frame.

The mini-LED module is a set of boards carrying many small LEDs under a diffuser and quantum-dot film. A dead zone shows as a dark square or block; a driver fault can kill a whole region.

Blooming (halo around bright objects on black) is normal mini-LED behavior and changes with firmware and the Local Dimming setting. Do not order parts for it.

Components & tests

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Official manufacturer documentation

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): LCD TV with the panel removed, showing the grid of lit LED backlights by RobertKuhlmann, CC BY-SA 3.0

Diagnostic guides for this appliance

Guide · TV

Soundbar won't turn on with the TV, or TV remote won't control its volume (HDMI-CEC)

One-remote control depends on HDMI-CEC over the ARC/eARC cable. Disabled CEC, the wrong HDMI port, an optical connection, a poor cable or a TV update that switched settings off cause nearly all of these calls.

7 steps ~30 mineasy
Guide · TV

Soundbar audio cuts out, pops or drops with movies/Atmos (ARC/eARC)

Dropouts usually come from an unstable ARC/eARC handshake or a format the chain doesn't handle well. Work through cable, firmware, CEC conflicts and the TV's digital audio format; optical is a stable fallback without Atmos.

8 steps ~40 mineasy
Guide · TV

Projector won't turn on or shuts off (reading the indicator lights)

Projectors protect themselves: overheating, lamp at end of life, and lamp-cover interlocks all stop the light source. Read the indicators against the model's table, then fix airflow, lamp seating or lamp life.

6 steps ~30 mineasy

Other tvs manuals

Manual · TV

Samsung Crystal UHD CU8000 / DU7200 / DU8000 (2023-2024): quick sheet

Samsung Crystal UHD 4K LED sets one step above the CU7000: CU8000 (2023, e.g. UN55CU8000FXZA, UN65CU8000FXZA; 43-85 in), DU7200 (2024 retail-channel model, e.g. UN65DU7200) and DU8000 (2024, e.g. UN65DU8000FXZA). Year letter: C = 2023, D = 2024. The 85-inch CU8000 and DU8000 use a different 120 Hz panel with HDMI 2.1 features; do not treat them like the smaller sizes. The basic TU7000/CU7000 have their own sheet.

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Manual · TV

Samsung The Frame LS03 (LS03B / LS03C / LS03D): quick sheet

Samsung The Frame lifestyle TVs with matte screen and One Connect box: LS03B (2022), LS03C (2023), LS03D (2024), e.g. QN43LS03DAFXZA, QN55LS03DAFXZA, QN65LS03DAFXZA, QN75LS03DAFXZA. Sizes 32 in (Full HD) and 43-85 in (4K). 43 and 50 in are 60 Hz; 55 in and up are 120 Hz.

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Manual · TV

Samsung OLED S90C / S90D (2023-2024): quick sheet

Samsung 4K OLED S90C (2023, e.g. QN65S90CAFXZA) and S90D (2024, e.g. QN65S90DAFXZA; 42, 48, 55, 65, 77, 83 in). Panel source varies: the 83 in S90C and the 42/48/83 in S90D are reported to use LG Display WOLED; 55/65/77 in S90D may use either Samsung QD-OLED or LG WOLED ('panel lottery').

7 components5 common failuresSamsung
Samsung Neo QLED QN85 / QN90 Mini-LED (B / C / D, 2022-2024): quick sheet · OnCall Tech