c. Check that the RPM control has not become loose and moved
with respect to the shaft of R3. If so, refer to paragraph 4.7.4.
d. Check capacitor C5 for proper value.
4.5.11 INCORRECT RATIO BETWEEN RANGES.
In the following steps, the calibration settings are those to be
used with a 60 -cycle motor; if a 50 -cycle motor is used, ob -
tain corresponding settings from Table 4-1 or multiply the-
settings by 5/6 .
If the 6:1 ratio between frequency ranges is not correct within l%,
see Figures 4-1 and 4-2, and proceed as follows:
a. Setup a synchronous motor fitted with a disk, as described in
b. Remove the instrument from the case (refer to paragraph 4.4.6)
so that potentiometer R7 and R8 are accessible. These patentiometers
are located one on each side of the range switch on the etched board.
c. Allow the instrument to warm up for at least one hour.
d. Set the range switch to the 4000-25,000 RPM range and set the
RPM control to 21,600 RPM. Adjust the HIGH CAL control on the panel
to obtain a stationary pattern of 12 images.
e. Set the RPM dial to 5400 RPM and adjust the LOW CAL control
on the panel to obtain a stationary pattern of 3 images.
f. Repeat steps d and e until no further adjustment is necessary.
g, Set the range switch to the 670-4170 position and set the RPM
dial to 3600 RPM.
h. Adjust potentiometer R7 so that a stationary pattern of 2 images
is obtained. Check operation at 900 RPM by adjusting the RPM control
until the image is stationary. The correct setting should be less than
one -half division from the 900 RPM mark. If the setting is not correct,
repeat steps d, e, f, and check setting again.
1. Set the range switch to the 110-690 RPM position and set the
RPM control to 600 RPM.
j. Adjust potentiometer R8 so that a single stationary image is
obtained. Check operation at 150 rpm. The stationary-image setting
should be within one-quarter of a division of the 150 RPM mark. If not,
repeat steps d, e, and f before checking this setting again.
k. If the above procedure does not correct the difficulty, try re -
placing tube V1 (5965), and check values of C4, C5, and C6.
4-6. TEST VOLTAGES.
Test voltages from tube pins to ground are shown on the schematic
diagram, Figure 4-7. Voltages are dc unless otherwise indicated.
Deviations of up to 20 percent from the stated dc voltage should not be
considered abnormal. Voltage ranges given for V1 are to be measured
with R3 (the RPM control) either fully clockwise or fully counter clock-
wise (refer to VOLTAGE MEASUREMENTS on schematic diagram).