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So I have a Compaq CQ56-109WM and it recently been dropped. When I hold a flashlight to it I can see everything fine. But the their is no backlight to it. The only thing is I think I need to buy a whole new screen but not to sure. Can anyone help me decide which one I would need to buy?

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Dani AI

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As pointed out, the flashlight test reported by (image visible only when shining a light) almost always means the picture data is OK but the illumination is not — however, the exact repair depends on which kind of panel that CQ56 actually has. The CQ56-109WM was shipped with different supplier panels (some LED, some CCFL), so an inverter is not always present or required. (laptopparts.ca)

Recommended diagnostic sequence (in order):

  1. Confirm the GPU/logic is working with an external monitor or by observing BIOS/boot screens — if those are fine but the laptop lid is dark, that narrows the fault to the screen/backlight system.
  2. The flashlight test is the classic confirmation that backlight power is missing even though the LCD image is being driven.
  3. Power down, remove AC and battery, remove the bezel to read the LCD sticker and inspect the display connector: a CCFL panel will have a small two‑wire CCFL/inverter plug, while LED panels use a multi‑pin LVDS/eDP connector and usually no separate inverter. These checks determine whether to look for an inverter or a full panel replacement. (ifixit.com)

Repair guidance and safety notes:

  • If the panel is CCFL, replacing the inverter (or its SMD fuse) is the cheapest first step; check continuity only with power removed. Do not probe inverter high‑voltage outputs while powered — CCFL inverter circuits generate dangerous voltages. If low‑voltage supply to the inverter is absent, the fault may be on the mainboard or cable.
  • If the panel is LED, the backlight is part of the LCD assembly and the usual fix is a full panel swap. When ordering parts, match the exact LCD part number on the sticker (manufacturer + model/revision and connector position). (ifixit.com)

Because this was a drop, hinge/cable damage is a common secondary cause; replacing the correct part (inverter vs. whole panel) after verifying the part numbers is the most reliable approach, as recommended. (vymena-displeje.cz)

Recommended Answers

All 11 Replies

Member Avatar for Rik_

I'd say you just need a new inverter!

Member Avatar for Rewired

Cool Rik! I'm going to give that a try soon and see

Member Avatar for Rik_

The inverter will have a surface mount fuse on it. You could check that with a multimeter if you have one. DO NOT TEST IT LIVE as the inverter produces 2,000 volts or more.

Member Avatar for Rewired

Is all inverters the same? Because it's hard to find one for my model laptop.

Member Avatar for Rik_

No they aren't unfortunately!

Member Avatar for Rewired

:/ Where could I find one for my model laptop?

Member Avatar for Rik_

Have you checked eBay?

Member Avatar for Rewired

Yeah but it was for the CQ56-G## something

Then I found this site:

Member Avatar for Rik_

You may want to add HP to your searches as Compaq are owned by HP.

It would be a good idea to remove the faulty inverter and check it's part number!

Edited by Rik_ because: n/a
Member Avatar for Rewired

Just tried and a whole bunch came up as Pavilion, only searches for Compaq comes up but its hard to find the inverter for it. Unless it's fine to get one in the same series.

Member Avatar for Rik_

Remove it and get it's part number is my advice.

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