Changing an iMac's HVT

par Lionel - 17/03/2004

THANKS TO APPLEANDME FOR THIS ARTICLE.

Then unscrew the video card (3 screws), unplug all connections to this card (quite a number, and not always easily accessible), but plugging them back should not be a problem.

The last piece to unplug is the HVT. First remove the suction cup which is located on the display. Then cut the 2 red and black wires originating from the electron beamer (the grid located at the top on the photo). It is possible to remove this grid to access directly these 3 wires' plugs, but it is so difficult that I ended up cuttingthem and soldering them back once finished.

Once it is done, you have the video card in your hands, and you now have to remove the HVT by unsoldering the 12 connectors.

As mentioned in the picture, a capacitor and a diode are preventing the proper installation of the new HVT. So, first visualize the orientation of the capacitor, unsolder both (capacitor and diode) , then solder them back to the corresponding location on the other side of the video board.

Place the new HVT, and solder it via 10 connectors (2 connectors less than the old one as shown in the picture).

Solder back the red and black HVT wires previously cut, then fix the suction cup back to the display. Plug back all connections, screw the video card back on.

That's it, the new HVT is now in place. Before reassembling the iMac, you need to :

Put back the metal plate (see first step).

Plug back the motherboard to the video card/display power.

Plug the computer as it is and boot up.

This time, when you press the start button it should boot properly, but it is possible that your display still remains black; let it go until the boot procedure is finished (HD activity should stop, so the OS is launched).

You can then setup the Focus and Screen parameters directly via the HVT.

Once everything looks good, Shut down the computer, disconnect it from the power plug, press a few times the start button to release any tension in the condensators, reassemble the iMac (motherboard + plastic case), plug back, boot and ?. Enjoy.

AppleAndMe, with the help of MacBidouille and Repartout forums.

Translation : Eric