NEC PG Series

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DEFLECTION BOARD

Great! Well, let's lift the Deflection board. The Deflection board is the board with the large heatsink attached to it. You will find 2 screws or 4 screws on the back edge of the board that have to be loosened. The 2 lower screws in the picture above are held by plastic washers and DO NOT come out. There MAY be a metal shield that has to be removed. It is often already missing. The Deflection board should now hinge up. Below the deflection board you will see the red and green CRTs, as well as the CONVERGENCE (C-Drive) and FOCUS (F-Drive) boards. If you need to
adjust the projector for ceiling or floor mount, you will need to flip a series of connectors on the CDrive and Deflection board first. The diagram for this is plainly marked on the projector cover, and if needed, should be done now.

At this point the projector should be configured as outlined on the cover for the mounting method desired. Now look at the tubes. The front is a bell shaped glass envelope tapering down to a thin tube called the neck. The first item right up against the .bell. is the deflection yoke. Look for 2 small rings with tabs on them (A). Those are the CENTERING magnets. Moving these around the tube, and in opposition to each other allows you to position the raster in the center of each tube. Now is a good time to carefully cut the silicone dab that should be on the rings. Do this on all 3 tubes. Moving down the tube, you will see a long thumbscrew (B). This is the clamp that holds the
Yoke in position. Most likely you won't have to move this, but keep it in mind for later. The next assembly is the focus and astigmatism coil. Normally, this also does not have to be moved. After this you will see a set of 4 rings with tabs on them (C). These are the astigmatism magnets. These magnets control the shape of the electron beam inside the tube, and also affect the position. So the centering magnets and astigmatism magnets interact with each other and usually need to be adjusted alternately to achieve good results.

Proper adjustment of the astigmatism magnets is crucial to achieve tight focus across the screen, and will be explained further on. You might want to carefully cut the silicone on these rings as well. NOTE: If this is beginning to sound too difficult, I highly recommend hiring a professional for the job at this point. This is an advanced, but important procedure to achieve good results with a PG. It is also dangerous to the novice, since the following adjustments are made with power applied to the projector. I cannot stress enough that this is dangerous for the inexperienced.

There are potentially lethal voltages around the tubes, and if you are not reasonably comfortable with electronics, now might be a good time to bail out and call a pro.

For those still reading, on to the first adjustments.