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SETUP AND CONVERGENCE PROCEDURE
CAUTION: To avoid electrical shock,
take care not to touch the yoke conductors or
push against the anode cap.
Use a knife to brake free the magnetic rings
on the yoke, which are usually locked with
red varnish. Bring the adjustment tabs on
each pair of magnetic rings in line for the
starting point.
1.
Loosen the yoke clamp. Remove the yoke
wedges and the tape from the CRT.
2.
Connect a test generator to the video input.
3.
Turn the monitor on. Switch the test
generator to red field. Adjust the horizontal
and vertical raster size, on the remote control
board, for under scan. Let the monitor run
for at least half an hour.
4.
Check the auto bright control voltage with a
DVM. Connect the DMM to GND and pin 8
of the LM324
920 on the video board. The
voltage range is 4.0V to 4.4V. If out of
range, adjust this voltage to 4.2V by using
pliers to rotate the bottom knob on the FBT.
5.
Degauss the picture tube and front part of
the frame.
6.
Adjust the yoke position, on the CRT neck,
to the center of purity. One way to locate
this yoke position is to make a felt pen mark
on the CRT neck at the rear extreme of
purity and another mark at the front extreme
of purity. Make a third mark between the
two marks and set the yoke to this position.
Rotate the yoke to line up, the raster top line,
with the top of the picture tube. Tighten the
yoke clamp. Tilt the yoke side to side and up
and down while watching the red field to
verify that purity is good.
7.
Switch the generator to the red/blue grid.
Adjust the 4 pole magnets (center pair)
for convergence of the red and blue guns in
the center of the screen.
Tilt the yoke up and down for the best
convergence around the edge of the grid.
Insert the top yoke wedge. Tilt the yoke side
to side for the best convergence around the
edge of the grid and insert the rest of the
yoke wedges. Secure the wedges with tape.
10.
Switch the generator to the white grid.
Adjust the 6 pole magnets (Pair closest to the
video board) for convergence of the green
gun. Step #10 and this step may have to be
repeated for optimum convergence.
11.
8. If the yoke position adjustment does not
produce good purity, adjust the purity
magnets. Tabs closest to the yoke winding.
If the corner convergence is still not
acceptable, shunts may be used to correct
this problem.
Shunts are available from CERONIX.
Shunt order number is CPM2011.
12.
9.
Always keep one hand free to avoid making a
complete electrical circuit.
920
100