Dark spots, uneven backlight and clouding on a TV screen — repair in Riga
When dark spots, light clouding on a uniform background or uneven backlight along the edges appear on a TV screen, the first question is always the same: is it the backlight or the panel itself? The answer decides everything — a backlight can often be repaired at a reasonable price, but panel damage almost never makes economic sense to fix. At the SATER service centre on Silmaču iela 6 we have been making this call since 1993, when we started in workshop No. 2 of the old "Elektrons" factory. Backlight-side faults — failed LED bars, diffuser sheet warpage after humidity exposure, pressure marks from bad packing — are repairable, because they sit behind the panel and do not touch the pixel layer. Panel-side faults — failed TFT rows and columns, mura, OLED pixel degradation — are built into the glass itself, and replacing the panel almost always costs more than a new television. We tell you honestly which category your problem falls into before any work starts. If it is the backlight, we open the TV, replace the LED bars, clean the light guide and repair the diffuser. If it is the panel, we say so and do not take money for pointless work.
Likely causes
- Failed LED bar in a direct-lit array — A single bar failure in direct-lit TVs creates a visible dark zone on one side of the screen — we replace the bar and recalibrate current across the others for even brightness.
- Edge-lit backlight LED burnout — In edge-lit models, burnt LEDs cause a dark corner or vignette — usually the whole side LED strip needs replacing.
- Diffuser sheet warp or separation — Humidity makes the plastic diffuser sheet bow or delaminate from the light guide, producing bright clouds and general unevenness across the screen.
- Pressure damage to the LCD layer from packing or impact — Bad packing during transport or an object pressed into the screen leaves permanent dark marks directly on the panel — this is a panel-side failure.
- OLED compensation IC degradation — In older OLED sets the compensation chip no longer levels out pixel aging accurately, creating uneven brightness across the whole screen.
- Dust ingress onto the light-guide plate — Over years, dust finds its way inside the TV and settles on the light guide, producing blurred dark patches — a careful clean restores uniformity.
What you can check yourself
- Play a solid grey or white test pattern from YouTube (search "TV backlight test pattern") and watch the screen in a fully darkened room.
- Turn off all room lights and compare the centre of the screen with the corners — uneven edge brightness points to an edge-lit fault.
- Photograph the screen showing the test pattern — phone cameras often exaggerate defects the eye misses and help with diagnosis later.
- Check whether the spots appear on several input sources (HDMI, USB, network) — if they do, the fault is inside the TV, not in the signal.
When to bring it in
If the spots are visible on a clean grey test pattern and stay in the same place regardless of content, it is time to bring the TV to the service centre. We open the set and visually inspect the backlight, the diffuser and the panel on a professional test rig. Distinguishing a backlight fault from a panel fault is critical — the first is repairable at a sensible cost, the second almost never is. We make this call honestly and quickly, and if it is the panel we say so, before anyone pays for a pointless repair.
Fast on-site diagnostics. Repair warranty: 3 months.
Affected brands
Frequently asked questions
Why customers choose SATER
- Dedicated specialist per category. Your device is repaired by an engineer who only handles this device category — never others.
- 30+ years of experience. The service centre has been operating since 1993.
- On-site diagnostics. Diagnostics are free even if you decide not to proceed with the repair.
- Custom-built batteries. We don't just replace batteries — we build custom packs from SONY, MOLICEL, SAMSUNG, LG and PANASONIC cells.
- We serve all of Latvia. Our service centre is in Riga and we accept devices from anywhere in the country.