COMMON PROBLEMS & TROUBLESHOOTING

Below, you will find a number of common problems that can occur in the Barco 800 series (and other projectors). Be careful when looking into the tubes. Use sunglasses to prevent serious eye problems. Staring into a raster pattern while running at normal contrast/brightness settings will have you seeing squares for hours. If you wish to make some of the adjustments that are described here, read the disclaimer prior to doing so. Fiddling with Barco electronics can be very dangerous.

Everything looks OK

Normal tube image
This is how a tube should normally look. Depending on the video source you may see a slight edge around the actual image, showing the raster on the tube. The lovely Laura Gemser will be playing tube surface model today :) Note that the images on this page are slightly exaggerated examples created in photoshop to give you an idea what the symptoms look like.

G2 too high

Blue / Red / Green veil on image
This problem occurs if G2 for the tube is set too high. G2 (Tube Gain) pretty much determines the light output range in which the tube will perform. If it is set too high, the bottom end of the range will appear washed out, while dark areas on the screen are colorized with the color of the tube that has too high G2. You can set G2 for the tube as follows: Projecting a black image (see video patterns section), set the projector to D6500 in the color menu. Set brightness to 50 and Contrast to 0. Look into the tube and carefully turn the G2 Pot on the side of the projector. The G2 pots are below the focus pots (table mount) or above the focus pots (ceiling mount). Turn the G2 pot until you can JUST see the raster lighting up. Try to set the raster gain so the vague square equals that of the other tubes in brightness. The pots are close to LETHAL power supply components, so be careful when adjusting this.

Defocused tube

Focus problems
In some cases, the focus of the electron beam on the tube surface can be off. Electronic focus is set by turning the focus controls on the side of the projector. You need to be VERY careful when doing so, as these controls are very close to the power supply of the projector. Touching the wrong things can be LETHAL. The focus pots are below (ceiling mount) or above (table mount) the G2 controls. Select your video source, put on some sunglasses and look into the tube while carefully adjusting the focus pots for each tube while projecting the Genlocked pattern that can be found in the "Random Access" menu of the Barco. Note that in many cases, the blue tube will be set slightly out of focus (defocused) on purpose, to create more evenly blues and prevent yellow areas in bright images. Also note that after tweaking electronic focus, you will need to redo all your convergence and color adjustments as they are affected by this setting.

G2 too low

Only peaks are showing
This problem occurs when G2 is set too low and the tube will only light the brightest areas in the image. Try adjusting the G2 (see above for instructions) to see if the problem goes away. If you find that nothing happens aside from the tube getting brighter, the problem is likely related to the RGB output amplifier board behind the tube neck (see below). Fix it or get it fixed and readjust your G2.

Ghosting

Ghosting
A slight ghosting effect often occurs when bad cable is used that is pickup interferance or when cable is used that is spanning a distance that is too long. However in some cases ghosting will appear when the RGB output board FET for one of the tubes is failing. When displaying a genlocked pattern, you will see a slight ghosting to the right. See below for other symptoms indicating failing a failing RGB amplifier board and how to resolve this problem.

RGB output stage failing

RGB amplifier board failing
One of the most common problems with the 800 series is the 2SK511 FET on the RGB amplifier boards behing the tube necks failing (indicated as "Q6" on the PCB). Usually the first sign of this is image ghosting or streaking to the right or a number of diagonal retrace lines appearing in dark scenes. After some time, the tube will start getting brighter and brighter causing the problems associated with too high G2 settings. Most people wont notice the other problems at first and simply turn down the G2 pot. The FET will just get worse however and should be replaced as soon as possible. This problem can easily be identified by swapping the boards with another tube as they are interchangeable. If the problem moves.. its likely the FET.

Tube burn

Burn
This is what we all fear. Burned tubes. This problem is caused by displaying a static image on the tube for a prolonged period of time. Many "good" projector deals turn out to be very expensive ones when the projector turns out to contain one or more burned tubes. Even displaying moving TV images can cause trouble as the network logo's are often in the same place causing burn. It's no fun watching a movie with a CNN logo burned in the top of your screen :( Well.. this tube has to be replaced. That's all there is to it.

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