the meter reading is low when connected
from any stator lead to the frame, the
windings are grounded.
t e r m i n e d by connecting its leads to
If the lamp fails to light, or if the meter
The voltmeter
reading i s h i g h w h e n s u c c e s s i v e l y c o n -
will read up scale when the nega-
tive leads are connected together
nected between each pair of stator leads,
and the positive leads are con-
the windings are open.
nected together.
The polarity of
A short circuit in the stator windings is
mined by connecting the leads to
difficult to locate without laboratory test
the identified terminals of a bat-
tery .
the windings. However, if all other elec-
trical checks are normal, and the alter-
supply r a t e d o u t p u t ,
nator fails to
6. Transistor TR2
shorted stator windings are indicated.
A. Should read about 5-50 ohms, If zero
To replace the stator drive end frame
or well above 50, replace transistor.
from rectifier end frame, refer to "Bear-
ing Replacement" on page 10D-16, and
B. Should read very high, If not, re-
pull leads and grommet through hole.
place transistor.
Place grease. on g r o m m e t a n d p u l l i n t o
hole during assembly.
C. Repeat Step A.
REGULATOR REPLACEMENT. After dis-
7. Transistor TR3
connecting the three identically colored
regulator leads, the regulator may be
If not, re-
A. Should read very high.
the attaching
replaced by
removing
place transistor.
screws a n d d i s c o n n e c t i n g t h e r e g u l a t o r
lead from the heat sink.
B. Should read about 5-50 ohms. If zero
or well above 50, replace transistor.
If previous checks indicate the regulator
should be repaired, proceed as follows:
C. Repeat Step A.
1. The panel board is shown without the
sealing compound so the seven (7) serv-
If
8. Diode D5 should read 5-50 ohms.
iceable parts can be easily identified (see
zero or well above 50, replace transis t o r .
9 . D i o d e t r i o D 1 , D 2 , a n d D 3 - E a c h d iode
2. Remove screw, t r a n s i s t o r T R 1 a n d
If zero or well
should read 5-50 ohms.
pry apart heat sink and panel board with
a b o v e 50 ohms, r e p l a c e d i o d e b e i n g t e s t -
screwdriver.
ed.
3. Carefully inspect printed circuit for
10. Capacitor C2 should read high. If
zero, replace capacitor.
4. Carefully inspect for broken parts.
5. Check components as f o l l o w s ( s e e
Use
F i g u r e 1 0 D - 1 7 o n p a g e 10D-15):
1 - 1 / 2 v o l t o h m m e t e r o n l o w scale.
C h a n g e ohmmeter to X10 or middle
scale.
SCRATCH HARD WITH SHARP INSTRU-
MENT TO BREAK THROUGH TRANSPAR-
ENT COATING OVER SOLDER TO MAKE
11 . Potentiometer R2-With ohmmeter con-
OHMMETER CONTACT. Use 50 watt sol-
nected, turn potentiometer slotted screw
dering gun.
Ohmmeter needle should deflect slightly.
If no deflection at all, replace R2.
10D-14
