Generator And Controls Troubles - Hobart JET-EX 4 Operation And Maintenance Manual

TROUBLESYMPTOM
AND CONDITION
GENERATOR AND CONTROLS
1. Generator will
not build up
voltage at all
when push-to-
build-up volt-
age switch
(S407) is
operated.
Engine running
normally
May 20/89
PROBABLE CAUSE
A. Flashing power not
reaching generator
revolving field (L406).
(1) Defective push-to-
build-up-voltage
switch (S407)
(contacts stuck in
open position)
(2) Defective diode
(CR401)
(3) Excessive brush
wear, or poor
contact of brushes
to slip rings.
B. Voltage sensing relay
(K404) defective.
Relay contact 1-7 or
3-9 stuck in open
position.
TEST, CHECK, AND/OR
REMEDY
A. Check as follows:
(1) 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.
(2) Use ohmmeter to check
diode on back of push-to-
build-up-voltage switch.
Replace diode if defec-
tive.
(3) Check brushes closely for
excessive wear and check
brush contact with slip
rings. Replace brushes
if excessively worn, and
make sure that brush
contact with slip rings
is proper.
B. Connect a jumper lead
between pins 1 and 3 on
voltage sensing relay
(5, 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 C.
OM-2049
3-1
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