Checking And Adjusting - Philips PM2517E Service Manual

Automatic digital multimeter

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Table of Contents

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C H E C K I N G A N D A D J U S T I N G

5 . 1 .

G E N E R A L

T h e t o l e r a n c e s i n t h i s c h a p t e r c o r r e s p o n d t o t h e f a c t o r y d a t a , w h i c h o n l y a p p l y t o a c o m p l e t e l y r e - a d i u s t e d

i n s t r u m e n t . T h e s e t o l e r a n c e s m a y d e v i a t e f r o m t h o s e m e n t i o n e d i n t h e T e c h n i c a l D a t a ( C h a p t e r 1 ) .

For a complete re-adjustment o{ the instrument the sequence in this chapter should be adhered too. When

individual components, especially semi-conductors are replaced, the relevant section should be completele

re'adjusted.

T o c a l i b r a t e t h i s m e a s u r i n g i n s t r u m e n t o n l y r e l e r e n c e v o l t a g e s a n d m e a s u r i n g e q u i p m e n t w i t h t h e r e q u i r e d

a c c u r a c y s h o u l d b e a p p l i e d . l f s u c h e q u i p m e n t i s n o t a v a i l a b l e , c o m p a r a t i v e m e a s u r e m e n t s

c a n b e m a d e w i t h

another calibrated PM 2517 . However, theoreticallV the tolerances mav be doubled in the extreme case.

T h e m e a s u r i n g a r r a n g e m e n t s h o u l d b e s u c h t h a t t h e m e a s u r e m e n t

c a n n o t b e a f t e c t e d b y e x t e r n a l i n f l u e n c e s .

P r o t e c t t h e c i r c u i t a g a i n s t t e m p e r a t u r e v a r i a t i o n s ( f a n s , s u n ) .

W i t h a l l t h e m e a s u r e m e n t s

t h e c a b l e s s h o u l d b e k e p t a s s h o r t a s p o s s i b l e ; a t h i q h e r f r e q u e n c i e s c o . a x i a l l e a d s

s h o u l d b e u s e d .

N o n - s c r e e n e d

m e a s u r i n g c a b l e s a o t a s s e r i a l s s o t h a t t h e m e a s u r i n g i n s t r u m e n t w i l l m e a s u r e H F v o l t a g e v a l u e s

o r h u m v o l t a g e s .

B e f o r e c h e c k i n g a n d a d j u s t i n g r e m o v e b o t t o m c o v e r . F o r c a l i b r a t i n q t h e i n s t r u m e n t t h e a d i u s t i n g e l e m e n t s

a r e r e a c h e a b l e a t t h e b a c k o f t h e b o t t o m p . c . b o a r d N 1 . I n c a s e o f a c o m p l e t e a d j u s t i n g o f t h e i n s t r u m e n t i t

may also be necessary to replace the adjusting resistors. which are reacheable at the tront of the bottom

o . c . b o a r d . l n t h i s c a s e t h e t o D ' a n d b o t t o m c o v e r s h o u l d b e r e m o v e d .

Fig.44.