Philips PM2517E Service Manual page 47

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3.3.6.
Power supply (Fig.26 and S)
T h e i n s t r u m e n t c a n b e p o w e r e d b y 4 x 1 . 5 V b a t t e r i e s o f b y a 9 V e x t e r n a l p o w e r s u p p l y ( p M 9 2 l g ) .
l n t h e P M 2 5 1 7 a s t a b i s t o r B Z X 7 5 C 2 V l i s i n c l u d e d i n t h e i n p u t l i n e o f t h e e x t e r n a l p o w e r i n p u t . T h e
voltage supplied to the power circuit is in case of 9 V external power supply - 7 V.
W h e n t h e p o w e r i s s w i t c h e d o n , t h e p o w e r c i r c u i t w i l l s t a r t o s c i l l a t i n g . T h e o s c i l l a t i n g f r e q u e n c y i s : 1 6 0 k H z .
The input voltages are transferred to ! +8.5 V and = -8.5 V. The circuit js stabelized with the feed back
c i r c u i t c o n s i s t i n g o f z e n e r d i o d e V 8 5 0 { B Z X 7 9 C 1 0 ) , V 8 5 2 ( B A W 6 2 ) , s u p p t i e d t o V 8 0 1 ( B C 5 5 8 ) .
The following voltages are measured in the power circuit oI a PM 2511 with a 9 V external power supplV
P [ / ] 9 2 1 8 :
o v ü
I
I
I
l
I
t
t
t
o , Ö
( a N o 0 E v 8 5 l )
- 7 5 V
- r ? 5 v
+ 0 5 v
0 " 0
_ 9 V
o u ü
s T 2 5 l 8
C A T N O D E ! 3 5 I
. t
I
t
l
t
F R E O U E N C Y v ^ 1 6 0 k B z
N O T ' C H A N 6 N G T H € N P U I V O L T A G E C I I A N G € 5 ' I i E F R E O U E N C V
Fig.
.
Dependent to the function selected the supply voltages are supplied via the function
selecter to the integrated
c a r c u i t .
The current source is only used in the iunctions e . oC ana *.
T h e R l / S c o n v e r t o r i s o n l y u s e d i n t h e f u n c r i o n s V -
, ( m ) A l .
To avoid overloading the power supply the LED's in the PM 2517 E are directly supplied
from the batteries.
q
q
rd
q
q
q
q
t