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Table 5.
Equipment Performance Checklist (Cont'd)
STEP
ITEM
ACTION OR CONDITION
PERFORMANCE STANDARD
8.
Internal bias voltage
s.
Set DC BIAS switch to OFF s. None»
(Cont'd)
check.
and remove the test prods
from the Model 75D.
9„
Internal bias current
check,,
a.
Check that DC BIAS
a. None.
INTERNAL ADJUST
control is fully counter¬
clockwise,,
b.
Set DC BIAS switch to
b. None„
+INT.
Co
Connect a 10 kohm 1/2
c„ None,
watt resistor across TEST
HI and LO binding posts.
d.
Adjust multimeter to
d. None
measure at least 5 mA dc.
e.
Connect multimeter prods
e. None,
to telephone plug so that
positive prod is at tip
terminal (center conductor
on plug) and negative prod
is at sleeve terminal (outer
conductor on telephone plug).
f.
Insert telephone plug into
f. Multimeter indicates
DC BIAS INTERNAL
zero on dc scale.
MONITOR 1 jack.
g.
Rotate DC BIAS
g. Multimeter pointer
INTERNAL ADJUST
deflects smoothly from
control fully clockwise.
zero to 4.4 mA - 10%.
h.
Rotate DC BIAS
h. Multimeter pointer
INTERNAL ADJUST
smoothly deflects back
control fully counter-
to zero on dc scale,
clockwise.
75D
b-370
59
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