A 17" LCD Display for an Apple computer produced between 2001 and 2004.

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Bad backlight on display. Burnt CFL?

I have an ADC Studio Display which has no backlight. I do not think it is the inverter because the power light stays solid and the backlight does not flash at start up. I have tested the CFL with 3.5V and no go! Does it need more voltage to test with?

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Keaton, I am not a Mac person, but I do know that your CCFL will require a higher voltage, a lot higher. The inverter literally supplies hundreds of AC voltage to your CCFL. Here is what the service manual says :"

1. Check ADC cable. Replace cable if damaged.

2. Check for bent pins in the ADC connector (note, it is normal for two of the pins to be slightly longer than the others). If pins are slightly bent, carefully straighten. If pins are severely bent, replace cable. Also, inspect or have the customer inspect the display port on the computer for broken pin dividers. If the display port is damaged it must be repaired before inserting the ADC connector.

3. Plug the display into a known-good computer with a known-good video card and ADC display port. Boot the computer and allow enough time to finish booting.

4. If the power button on the display is flashing, two short flashes then a long flash, in a delayed repeating pattern, this indicates trouble with either the inverter, backlight bulbs or related cables or connectors. With this in mind, continue with the

troubleshooting steps to determine the problem.

5. To check whether the LCD is working, press the launch button on the display which

will bring up the Display Preferences window (if the screen is blank you will not see the window). Shine a bright light such as sunlight or a high intensity lamp (see Important note, below) into the screen and at the same time notice whether you can see a faint image of the Display Preferences window or other desktop items on the screen.

• If desktop items can be seen, the LCD panel is working. The problem may be with

the inverter or backlight bulbs or related cables or connectors. Continue with the

troubleshooting steps.

• If no desktop items can be seen, the problem may be with the LCD panel or the

main board or related cables or connectors.

Important:

Lights get very hot and can quickly damage the display; be extremely careful not to allow too much heat next to the screen or other parts of the display and do not allow the light fixture to touch the screen, or damage can result.

6. Warning: The inverter board generates high voltage when the display is plugged in. Do not touch the inverter board components, pins or connectors, when the display is connected to the computer.

7. Disconnect the display from the computer, then open the display and check for secure connections at TMDS, Panel Power, J7, J2, J1, J3, CN1, CN2, CN3, CN4 and CN5.

Note: Refer to the Block Diagram in this manual for connector locations.

8. Plug the display into a known-good computer, then boot the computer.

9. Verify +24-28V at input of J7. If not, replace ADC cable.

10. Verify +24-28V at pin 1 of J2. If not, replace the main board.

11. Verify +5V at pin 5 of J3. If not, replace the main board."

I am certain the Mac Guru's will also know some more different ways. Hope this helps, good luck.

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No, 3.5 volts DC won't light the lamp you need 300 - 700 Volts depending on the CFL. Here's a simple inverter circuit you can built to test your CFL's Diagram.

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