Hobart Jet-Ex 4D, Руководство по эксплуатации и обслуживанию

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Generator and Controls
Trouble, Symptom and Condition Probable Cause Test, Check, and Remedy
1. Generator will not build up
voltage at all when
push-to-build-up voltage switch
(S407) is operated. Engine
running normally.
a. Flashing power not
reaching generator
revolving field
(L406) .
Check as follows:
b. Defective
push-to-build-up-voltage
switch
(S407) contacts
stuck in open position
Momentarily connect two
jumper leads across the
push-to-build-up-voltage switch;
one lead across the terminals
on the left side and the other
lead across the terminals on the
right side. If the voltage builds
up, replace switch.
c. Defective diode (CR401) Use ohmmeter to check diode
on back of push-to
-build-up-voltage switch.
Replace diode if defective.
d. Excessive brush wear, or
poor contact of brushes to
slip rings.
Check brushes closely for
excessive wear and check
brush contact with slip rings.
Replace brushes make sure
that brush contact with slip rings
is proper.
e. Voltage sensing relay
(K406) defective. Relay
contact 1-7 or 3-9 stuck in
open position
Connect a jumper lead between
pins 1 and 3 on voltage sensing
relay
(2, Fig. 3)
. If voltage then
builds up when switch S407 is
pushed, voltage sensing relay is
defective and must be replaced.
If voltage sensing relay is good,
proceed to Step f.
f. Generator revolving field
(L406) defective.
Locate yellow and red-orange
wires on the right terminal strip
at lower rear of control panel.
Disconnect the yellow and
red-orange wires which go
down to the generator.
(Refer to
connection diagram 180435
Chapter 5)
.
Measure resistance between
these two wires should be 6 to
8 ohms. If reading indicates an
open, short or lower than
normal resistance, proceed to
Step g.
DO NOT operate the generator set
to deliver power to an aircraft when
any protective device or other
component is jumpered.
CAUTION
OM-2063 / Operation and Maintenance Manual
Jet-Ex 4D / Spec. 7003A-3 / Generator Sets
Dec 31/92 Chapter 2-2
Page 9