Onan MJA Series Service Manual page 110

108
REVOLVING FIELD GENERATOR
TROUBLE SHOOTING CHART II (Cont.)
NATUHE OF
TROUBLE
Output voltage slow to build
up and higher than rated \'01 ­
tage after bUlld up
Output voltage slow to build
up and ten to twenty per cent
above rated voltage aiter
build up .
Output voltage builds up nor- Shorted winding in
mally
but
less than rated
Control Reactor
voltage after build up
Output voltage builds up nor ­
mally with shghUy less than
rated volLage at no load and
low voltage at full load
Output voltage builds up nor ­
mally but 20 percent above
rated voltage a!1er build up.
Voltage regulation pour.
Output voltage uuilds up nor ­
mally but is twenty five
Pt!l'
ct:nt
above
rated vo11..;1.ge after
lJuild up
Output voltage builds up 1I0r­
mally but 125 to 150 per cellt
above rated voltage alter
build up
Output voltage builds up 110r­
mally but 150 to 200 percent
above rated voltage after build
up. No regulation possible
PROBABLE
CAUSE
Open circuit in une or
more Control Rectifier
Open in one Fie ld
Rectifier
Open circuit in Gate
winding G I-G 2 of Re ­
actor A or B
Compound winding
S
l-~
installed bac k-
war or has open
circuit.
Compoun~
winding S1 ­
S2 installed uackward
tlu'ough one Heactor
(A or
n) .
Check circuit connec-
Control winding C l-C 2
of Reactor A or
n
tions of bot!J llehctors
polarized incorrectly A and D
Shorted turn in Control
windiug or Re­
actor A or B
Relay illoperative
Check cOlltillUlty from
£1 to
thl'Ougb Con­
lrol CiI·cuit
Open in Control Circuit
COlUtECT1VE
ACTION
Test rei.:lifier and re­
place
if
ddecUve.
Check soldered
COll ­
nectiollS to rectifiers
~-
Test rectifiers and re ­
place
if
defective
If
Field Rectifiers 1
and 2 check okay,
check cOlltilluities of
Gate windings GI-G2
. Test Control ReactOl·
and replace
if
defective
Check wiring diagram
for pularity of Com­
pouud windL.~s through
Reactors A and Band
test for continuity
Check wiring diagram
lor polarity or Corn-
pound winding 1hrough
Heactor A or B
Test Reactors A and D
ior shorted turn and re ­
place
if
defective·
Checkcnil continuity;
replace
if
defective
Open circuit in Control
Rectifier bridge
Shor1ed turn in gate
winding G I-G2 of Re­
actor A or B
Check continuity from·
the jUllclion of Control
Itediners 1 and 2 to
the
jUlldio;;
of COlltrol
Rectifiers 3 ann 4
Test Reactors A and B
lor shorted turns and
replace if defe<:tive
I