NEC MultiSync 2A Service Manual page 17

(3) Cut-off Adjustment (0.08Vp-p all white signal)
a) Contrast Control
Brightness control
b) Short TP451 and TP551 at 12 k0
Turn the screen VR clockwise a little by little until a single color appears horizontally. Adjust
the screen VR so that the color can faintly be seen. This color is the reference color for the
cut-off adjustment.
c) Turn the bias VRs for the colors other than the reference color counter clockwise for until they
are as bright as the reference color.
d) Release the shortcircuit between TP451 and TP551.
Perform the cut-off adjustment in as dark a place as possible to make the white
NOTE:
tracking which follows better.
(4) SUB BRIGHT VR Adjustment
a) Contrast control
Brightness control
b) Receive all black signal.
c) Adjust VR707 to VR709 so that the background raster becomes white.
(5) White Balance Adjustment
a) Contrast control
Brightness control
b) H gray scale (16 gradations).
(Window pattern - within a range in which there is no ABL.)
Check that the white balance is proper for all gradations.
If not, fine adjust the GAIN VR, VR701 and VR703 to make it white .
NOTE: Do not move VR702: G.GAIN
(6) Focus Adjustment
(4-dot missing signal)
Contrast control
Brightness control
Turn the focus control and adjust for the optimum focus.
(7) Purity Adjustment
a) Be sure that the display is not being exposed to any external magnetic fields.
b) Ensure that the spacing between the Purity, Convergence Magnet, (PCM), assembly and the
CRT stem is 29 mm ±1 mm. (See below diagram)
c) Produce a complete, red pattern on the display. Adjust the Purity magnet rings on the PCM
assembly to obtain a complete field of the color red. This is done by moving the two tabs in
such a manner that they advance in an opposite direction but at the same time to obtain the
same angle between the two tabs, which should be approximately 180°.
d) Chec k the complete blue and complete green patterns to observe their respective color
purity. Ma ke minor adjustments if needed.
Fully clockwise
Fully counterclockwise
Fully clockwise
Fully clockwise
Fully clockwise
At a point where no background raster appears.
Fully clockwise
At a point where background raster disappears.
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