Member Avatar for ocko56

I have and still use daily an old Dell C640 with a UXGA (1600x1200) screen that still serves my needs. However the screen starts off reddish when cold but within a minute or two it brightens to its good old self. This has been getting worse very slowly but suggests it will stop working some time soon.

My question is do I have to change both the screen and inverter or just one or the other elements to get back to new status?

Appreciate any help.

Trevor

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Short, practical diagnostic notes building on the exchange from and . When a laptop display shows a color/brightness shift that improves after a short warm-up, the simplest way forward is to isolate the display chain (panel, backlight/inverter, and flex cable) from the GPU/board so you can decide what to replace.

Try these checks in order:

  1. Connect an external monitor. If the external image is normal the motherboard/GPU is fine and the fault is in the laptop display chain.
  2. While the laptop is in the affected state, shine a bright flashlight close to the screen. If you can make out a correct image under the light, the LCD matrix is still receiving data and the backlight/inverter is the likely suspect.
  3. Open and close the lid slowly and gently wiggle the display cable area. If the tint or brightness changes with movement, suspect a damaged/loose LVDS/eDP cable or connector at the hinge.
  4. Inspect the inverter/backlight board (if accessible) for bulging capacitors, cracked solder joints or scorch marks. Many failures are heat/capacitor related and show warm-up behavior.

Notes, cautions and repair approach: warm-up symptoms often point to the backlight/inverter or aging CCFL lamps (older panels) and less often to the LCD data drivers. Replacing the inverter is a low-cost first test; if that fails, panel replacement is the next step. Do not probe high-voltage inverter outputs unless experienced — disconnect power and remove the battery before working inside. Record the panel and inverter part numbers before ordering spares so replacements match connector, resolution and mounting.

If unsure, a local repair shop can swap an inverter quickly to confirm the cause. Replacing a full panel is the least risky long-term fix if the inverter swap does not cure the issue.

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Member Avatar for finito

inverter? what does an inverter have to do with anything? Does the inverter not work? I cannot see why you would need to change the inverter?

I am assuming You are talking about a UPS device and referring it to as an inverter...

Member Avatar for ocko56

No! I have disassembled my laptop to see what the LCD screen components were etc. The screen requires an "inverter" card to drive the signal to the LCD screen. It is usually long and narrow and carries high-voltage warning stickers and therefore usually has shielding on it and mounted close to and behind the LCD screen itself. When search ebay for a replacement LCD screen I often came across replacement inverter cards. This suggests to me, although as yet I have not had any confirmation, that it may also be these inverter cards that become faulty rather than the screen itself. Hope this helps to explain my original question.

Member Avatar for finito

O I didn't realize you were talking about a laptop.

I guess you should.

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