Motorola M3000 Service Manual

2. Remove CRT from the front of the chassis by loosen-
ing and removing four screws; one in eac.h corner of the
CRT.
REGULATOR ADJUSTMENT
NOTE
Misadjustment of the low voltage regulator, or
the horizontal oscillator may result in damage
to the horizontal output transistor or pulse lim-
iter diode. The following procedure is recom-
mended to insure reliable operation.
1. Connect the monitor to an AC line supply; then
adjust supply to 120 volts (240 volts in some applications).
2. Apply test signal to proper input. Signal should be of
same amplitude and sync rate as when monitor is in service.
3. Adjust HOR. SET coil L50 (on the horizontal circuit
card) until display is stable.
4. Connect a DC digital voltmeter or equivalent pre-
cision voltmeter to the emitter of the regulator output
transistor, 0150 (or any +70 volt test point on the power
supply circuit card).
5. Adjust the 70V ADJUST. control, R158, on the pow-
er supply circuit card for an output of+ 70 volts. DO NOT
rotate the control through its entire range; damage to the
monitor may result.
6. When adjustment is complete, the AC line supply can
be varied between 105 and 130 volts AC to check for
proper regulator operation. With the regulator operating
properly, changes in display size should be negligible.
HORIZONTAL HOLD/OSCILLATOR ADJUSTMENT
Adjust the core of HOR. SET coil L50 until the horizontal
blanking lines are vertical, or the CRT display is stable
(synced).
DYNAMIC FOCUS ADJUSTMENT
The DYNAMIC FOCUS coil is factory set and should not
normally require further adjustment. However, if it be-
comes necessary, use Procedure No. 1 for touching up the
overall focus. Procedure No. 2 is provided if the CRT (V1)
and/or DYNAMIC FOCUS coil (L52) is replaced in the
field.
PROCEDURE NO
1. Adjust FOCUS control R70 (on horizontal circuit
card) for best focus in the center of the CRT.
4-19
2. Adjust DYNAMIC FOCUS coil L52 for best edge
focus.
3. Alternate between adjusting R70 and L52 until over-
all CRT focus is optimized.
PROCEDURE NO. 2
1. Connect an oscilloscope (DC coupled) between the
junction of R71 and C63 (on horizontal circuit card) and
signal ground.
CAUTION
High voltage is present.
2. Adjust the oscilloscope controls until one cycle of the
horizontal rate sinewave appears as shown in Figure 1.
3. Adjust the DYNAMIC FOCUS coil, L52 for a mini-
mum sinewave amplitude of not more than 125 volts P-P.
NOTE
Be sure that the one cycle appearing on the
oscilloscope is not a harmonic of the horizontal
rate sinewave. This may occur if the DYNAM-
IC FOCUS coil, L52, is misadjusted to the
extent that L52 will produce the second har-
monic. The coil must be adjusted to produce
the minimum amplitude of the fundamental
frequency only. Confirm the preceding by
momentarily connecting the oscilloscope across
the primary of T50. Only one cycle or pulse
should appear.
4. Observe the center of the CRT display and adjust the
FOCUS control, R70, for optimum focus; then record the
DC voltage (represented as amplitude "A" in Figure 1) be-
tween the DC 0 volt reference and the negative peak of the
sinewave.
5. Observe the edges of the CRT display and adjust the
FOCUS control, R70, for optimum focus; then record the
DC voltage (represented as amplitude "B" in Figure 1) be-
tween the DC 0 volt reference and the positive peak of the
sinewave.
6. Subtract the negative peak voltage from the positive
peak voltage. The difference becomes the voltage value to
which the DYNAMIC FOCUS coil, L52, must be adjusted.
7. While observing the sinewave, adjust the DYNAMIC
FOCUS coil, L52, until amplitude "C" (see Figure 1) equals
the difference voltage value determined in step 6.
8. While observing the oscilloscope, readjust the FOCUS
control, R70, until the negative peak of the sinewave is
positioned above the DC 0 volt reference line equal to the
voltage value recorded in step 4.

Motorola M3000 Specifications

General

Brand	Motorola
Model	M3000
Category	Cordless Telephone
Language	English