you'll hear a slight buzz.
If you touch a properly operating vibrator,
you'll also feel a slight vibration. One word of caution: if you replace
a vibrator, always put in a new buffer capacitor.
Other troubles are
similar to those for any conventional ac operated power supply. They are:
(c) Open filter choke.
(d) Shorted or leaky filter capacitor.
(e) A short in the B plus line leading to any stage using power from the
(f) Open bleeder resistor (if used as voltage divider also).
(4) Dynamotor type.
You'll find that dynamotor-type supplies are used in
practically all Army aircraft, and in many vehicular installations.
dynamotor power supplies are similar to those in rectifier units. Always
disconnect the dynamotor at the output terminals before you make any
resistance measurements in the filter circuit. Then you will be able to
make an accurate resistance check of the filter circuit components. Some
trouble points to check when examining a dynamotor power supply follow:
(a) Low battery voltage source.
(c) Worn dynamotor brushes.
Replace those that are less than 1/4 inch
long, measuring from the commutator to the brush pressure spring.
Watch the polarity mark when replacing worn brushes and watch for
broken or loose brush pigtails.
(d) Dirty or worn commutator.
If the dynamotor commutator is accessible,
hold a piece of fine sandpaper against the commutator while the
dynamotor is operating.
Don't use this method if the dynamotor puts out a high
voltage like the 1,000-volt dc output in Radio Set AN/GRC-19.
(e) Open or shorted armature windings.
f. Operational Check. Now that you've made a good visual inspection and checked
check will help you sectionalize trouble in your receiver or receiver-transmitter.
All this test consists of is operating the equipment