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Repairing Apple Multiscan 15 tint problem

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PROCEDURE FOR REPAIRING APPLE 15' MULTISCAN MONITORS WITH 'TINT' PROBLEM

Many owners of the Apple 15" Multiscan monitor have experienced problems with sudden and/or erratic changes in the monitor's colorimetry. The most common manifestation of this problem is the loss of the red component, leaving the display blue/green. Others have experienced a totally red screen, as well as other odd hues. Generally, this problem will at first be intermittent, then will gradually worsen to a 'permanent' state, although sudden permanent failures are not uncommon.

When my first 15" display went blue, I decided to investigate the problem myself (being an ardent tinkerer), before allowing myself to fall prey to the repair industry. I found, after some poking around, that the fix was very simple, and have since successfully repaired dozens of 15" monitors using my slightly unorthodox technique.

In every case I have encountered, the problem has been a loose connection somewhere on the color board, a 4x5"-ish printed circuit board attached to the back of the picture tube. I say somewhere because it's not always the same connection causing the problem. These loose connections were typically the result of a poor soldering job by the factory. In some cases there was no solder at all on the errant connection! Others would have a very small amount of solder that might have broken loose from the circuit board from ordinary thermal expansion/contraction during operation.

My repair procedure consists of the following steps:

  1. Disassembling the monitor.
  2. Locating the problem.
  3. The fix.
  4. Reassembly.

A word of caution: There is plenty of harmful electricity to be found in any monitor, especially if it is plugged in, even more especially if it's turned on. We're going to do BOTH, so be careful not to touch any components inside with your bare hands. Of particular concern is the ion trap (the big wire coming out of the side of the picture tube) and the transformer to which it is attached. As much as 20,000 volts can be found in this area! There are also a couple of capacitors nearby that carry considerable voltage even when the unit is unplugged. Enough said for now.

Tools needed: You'll need a Phillips screwdriver, something non-conductive you can poke around with (a chopstick works well), a soldering pencil with a reasonably fine point, a de-soldering syringe (Radio Shack - $2), a small piece of rosin core solder, and something to release the 2 catches on top of the monitor that hold the back on (I use an Allen wrench just small enough to fit in the holes). Also, if you can't see up close anymore, like me, you'll need your reading glasses and/or a magnifying glass.

PROCEDURE:

Disassembly: Turn unit upside down & remove the swivel base by lifting the locking tab and sliding the base rearward. Remove the two Phillips screws on either side of where the swivel base was. Place unit face down (screen down). Use a towel underneath to keep from scratching the screen. Using an Allen wrench, ice pick, nail, or anything you can get in the little square holes behind the top of the bezel (insert about 1"), pry gently outward from the monitor to release the plastic catches. This can be a little tricky if you've never done it before. I usually do one at a time while keeping rearward pressure on the back half of the cabinet. Once you've got them free, lift the back of the cabinet up a few inches, enough so you can reach in and disconnect the small speaker wire connector from the amplifier circuit board. This is easy to spot because it prevents you from fully removing the back. If you jerked the back off before you read the last sentence, you're probably still okay because the connector faces in such a way as it will pull out without breaking. Remember where that audio connector is for reassembly (small board on the side). Holding the sides of the bezel, you can ease the monitor back down to rest on its bottom. A magazine or newspaper underneath will keep it from scratching your dining room table, You are using your dining room table, aren't you? Now, the area we want to investigate, the color board on the rear of the picture tube, is enshrouded by a shiny metal shield box. This shield is soldered onto the board and must be removed. Using your desoldering syringe, heat up and desolder the 5 attaching points. Nothing particularly delicate of heat sensitive here, although you don't want to put too much strain on the picture tube connector. Once the attachments are desoldered, you should be able to detach the shield and lift it up off the board. Leave the ground wires attached to it and just set it aside.

Investigation: Situate the monitor so you can work behind it and still see the picture at the same time, reflected in a mirror (a patio door or window at night works, too). Connect your computer to the monitor's cable, and power everything up. Keep the kids and pets away! KEEP YOUR HANDS AWAY FROM ALL COMPONENTS! You should now be standing behind the monitor and seeing your blue/green or red picture reflected in whatever. Take your chopstick and begin wiggling the tiny ends of the components & wires that are poking out of the back of the color board while watching the reflected picture. Try to put a little side pressure on each stub you touch. You may grasp ONLY the edge of the color board with your fingers for support. Be patient! This can take a few minutes. My experience has been if the screen is blue/green, the bad connection is often in the top right quadrant of the board as you face the rear of the board (around 2 o'clock). For red screens, try 9 o'clock. In time you will find something that miraculously makes your picture normal every time you touch it. You have located the problem!

The fix: Power everything down and put new solder on the connection. Make sure you get a nice, shiny connection. Power everything back up, just to be sure you're okay, which of course you will be. You might want to carefully examine the rest of the connections to see if any are questionable. It's much easier to check everything while you're in there!

Reassembly: Re-attach the metal shielding box to the color board. Place unit screen-down again on a towel. lower rear cabinet onto unit enough so you can re-attach the speaker wire. Snap cabinet rear into place, reinstall screws & affix swivel base.

Although this sounds like a big operation, it can actually be done in less than a half hour. Try to find a repair shop, though, that will charge you a half hour's labor to fix it. HAH!