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a c c u r a t e l y ' u s e t h e v o l t r n e t e r a s a n u l l m e t e r u t i l i z i n g t ' h e r e f e r e n c e
potentiometer
as a standard vol-tage dirider'
b.
0verloäd Indicator
OL'25I
The overload indicators
(Figur.e 2.3-L)
provide a visual
alarm when
a' overload oecurs in arry of the
otrnrational
arnplifiers,
i.e.,
when
t h e s u n m i n g j r r n c t i o n i s n o t a t v i r t u a l . g r " o r r n d . A n o v e r l o a d m a y b e d u e
to improper scaling,
improper patching or loading'
W h e n t h e c o m p r r t e r i s i n i t i a l l y t u r n e d o n , a l l t h e i n d i c a t o r l a m p s
r n a y l i g h t ; h o w e v e r r i n a f e w s e c o n d s ' a s t h e a n p l i f i e r s s e t t l e ' a 1 l t h e
lamps should go out.
Should a larnp renajn
1it
it
could be a patching
e r r o r s u c h a s t h e f a i l u r e t o p r o v i d e u n . u s e d a m p l i f i e r s r , l i t h f e e d . b a c k
(via the four or six corurector bottle
plugs).
?rolonged overload will
not, damage an arnPlifier'
T o e l j m i n a t e t h e a u d i b l e s i g n a l - i n t h e i n i t i a l o v e r l o a d , i t i s
recorunended to turn off the s,r,litch designated
AIAIM on the panel'
c.
Digital
Voltrnet'er D-i,-25I
T h e d i g i t a J . v o l t r n e t e r ( w u ) D v - z s L i s t e r m i n a t e d i n t h e R e a d o u t
?anel 0c.151 area (Figure 23.2)
and is designated DV. As previously
m e n t i o n e d t h e D V r r a y b e b o t t l e d t o t h e S E L t e r r n i n a t i o n t o n o n i t o r t h e
selector
system voltages,
or r,rj-th a pat,ch cord the drgitai
voltmeter
n a y b e u s e d t , o m o n i t o r s i g n a l l e v e l s a t p r a c t i c a l l y a n y t , e r r n i n a t i o n j . r r
the ?re-Patch
?ane1.
The DVM has a 50 megohm
(minimun) full-tirne
input
:
irnPedance.
It will
take about 30 rninute tlrann up
tjme to operate the digital
v o l f u n e t e r i n t h e s p e c i f i e d a c e u r a c y f o r t h e m e a s u r e m e n t o f a r r a b s o l u t e
voltage.
For the analog eomputer' it
is not necessary to obtain
the
absolute voltage,
so the operator may use the
digital
voltmeter
I
(
T
t
I
- 2 l r -
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