ESI VideoBridge 2150, Service Manual

Page: 169 / 332

3 . 3 MEASUREMENT C I RCUI TRY
T h e e l e c t r o n i c s i n v o l v e d w i t h t he a c t u a l mea s u r i ng o f a compon e n t i s
c on ta i ne d on two c i r cu i t c a r d s . T h e D i g i ta l c i r c u i t ca r d pe r f or m s
t w o bas i c f u n c t i on s :
s i newave g e n e r a t i on , a nd a na l og - t o - d i g i ta l
conv e rs i on .
c i r c u i t r y , T h e Ana l og c i r c u i t c a r d h o l d s a l l o t he r me a s u reme n t
i . e . l e v e l
r e g u l a t o r , s ta nd a r d
(
r a n g e
)
r e s i s t o r s ,
ampl i f i e r s , p h a s e r e c t i f i e r , e t c . , n e e de d to make a m e a s u r e me n t .
3 . 3 . 1 D i g i ta l C i rc u i t Card ( p iN 5 3 5 2 2 )
3 . 3 . 1 . 1 S i n e G e n e r a t o r
MA S T E R
C L OC K
7 .68M H z
C OU N T E R
+ N
N PRESET
C OU N T E R
SYNC
RESET
x l
F RE QU E N CY
=
N l
N l
1 - 3000
N I l F
=
60 , OOOH z
N 1 3
F
=
2O , OOOH z
N
1
3000 F
=
20H z
7 .68MHz
1 28
(Steps in one
compl ete s inewave)
=
60, OooH z
0 0/1 800
GEN ERATOR
REVE RSA L
ROM
S I 2x8
x l
x 5
F RE QU E N CY
MU LT I PLIER
x l /xS
+5V
REF
DA C
x5
F RE Q U E N CY
=
N 2
N 2
=
2 - 30
N 2
=
2
F
=
I S0 ,OOOH z
N 2
=
30 F 1 O , OOOH z
7 .6 8M H z
1 28
(Steps i n five
complete sinewaves)
3 oo ,OOOHz
F i gure 3-3 .
S i ne Genera tor B l oc k D i agram
e l s l i
3
-
5
2 1 5 0 /2 1 60 5 /8 5
1 0V
p-p
AM P
�
To
Level
Regulator
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