M A I N T E N A N C E P R A C T I C E S
KEY ITEMS
D E T A I L S T E P S / W O R K I T E M S
Use agear close to the servo motor
t o r o t a t e t h e g e a r t r a i n .
Rotate the gear train until the pointer reads
zero.
Loosen the two screws (31) that hold resolver
to mounting plate.
R o t a t e r e s o l v e r u n t i l t h e o s c i l l o s c o p e t r a c e
is vertical and the voltage indicated on vtvm
n o . 3 i s a t a m i n i m u m .
Connect R1 -R2 winding to Xinput of oscillo¬
scope with R1 to the high side.
Oscilloscope pattern must show in-phase con¬
d i t i o n f o r c o r r e c t z e r o p o s i t i o n o f r e s o l v e r
rotor.
(d)
(e)
Se e t ha t th e r es o l ve r o u t p ut g e a r
d o e s n o t r o t a t e .
(f)
(g)
The in-phase condition exists when
the oscilloscope trace is inclined 45
degrees to the right as shown in
Figure 105.
(h)
Re-connect windings A2 and A1 to scope and
disconnect R1 -R2 windings.
Tighten screws (31) and rotate gear train
through 360 degrees.
Check null points at zero and 180 degrees
o n v t v m n o . 3 .
Check null points at 90 and 270 degrees on
v t v m n o . 2 .
If oscilloscope trace does not follow the direction
and angle of pointer, loosen screws again and
rotate resolver 180 degrees until the oscilloscope
trace is again vertical and the voltage at vtvm
n o . 3 i s n u l l e d .
Repeat steps (j) through (m) as found necessary.
SERVO AMPLIFIER -INDICATOR ALIGNMENT
(i)
Oscilloscope trace must follow the
direction and angle of pointer.
a)
(k)
(1)
(m)
(n)
H.
( 1 ) A m p l i fi e r G a i n Te s t
KEY ITEMS
D E T A I L S T E P S / W O R K I T E M S
Connect the test equipment to the servo
amplifier-indicator as illustrated in
figure 106.
Adjust the phase control potentiometer (of the
test "rig") for 0.5 millivolt (above residual
voltage) indicated on the vtvm connected to pin 7.
(a)
Clockwise rotation of the phase con¬
trol potentiometer should result in
clockwise rotation of the indicator
needle and vice-versa.
In this position R25 establishes
maximum g a i n o f Q 5 a n d Q 6 .
With R15 properly adjusted, the
fe e db a ck n et w or k a l l o w s 4 7 c p s t o
predominate in the motor drive
circuits.
(b)
Adjust the servo sensitivity (R25) control
(where applicable) fully counterclockwise.
Adjust the amplifier frequency control
(R15) for maximum indication on the dc
v c v m c o n n e c t e d a c r o s s s e r v o m o t o r .
(c)
(d)
April 1965
(R e v i se d J a n u a r y 1 9 6 8)
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