Head Alignment Without Tandberg Test Tapes; Demagnetizing; The Adjustable Tape Guides; The Erase Head - TANDBERG 12 Service Manual

5 .
b i n e d r e c o r d / p l a y b a c k h e a d u n t i l m a x i m u m r e a d -
ing is obtained on both output meiers. Ref. chap-
t e r 5 . 4 . 3 f o r l a t e r a l a d i u s t m e n t .
P l a y b a c k f h e t e s t t a p e N o . 3 . T h i s i s a f u l l t r a c k
pre-recorded tape with the following frequencies:
2 5 O - t 0 0 0 0 - 5 0 0 0 - i 0 0 0 - i 0 0 - 5 0 - 2 5 0 c l s
recorded at 7Yz i.p.s. tape speed. The tape con-
f o r m s w i t h t h e N . A . B . s t a n d a r d s . T h e o u t p u t t o l e -
r a n c e i s { - 2 d B f o r a l l f r e q u e n c i e s . T h e d i f f e r e n c e
in level between the two channels should be less
t h a n 3 d B a t a n y f r e q u e n c y .
T h e e r a s e h e a d i s s e t i n a p r e l i m i n a r y p o s i t i o n
w h e r e a p p r o x . 0 , 2 5 m m ( . 0 . l " ) o f t h e f e r r i t e c o r e
f o r t h e u p p e r t r a c k i s v i s i b l e a b o v e t h e t a p e . I n -
s e r t t h e t e s t i a p e N o . 9 , a n d r e c o r d a t O b O c / s
s i g n a l f r o m t h e g e n e r a i o r o n c h a n n e l 2 ( t r a c k 3 )
a t m a x i m u m r e c o r d i n g l e v e l . D i p t h e t a p e i n t o t h e
Magna-See solution and check that the re-recorded
t r a c k i s i n c e n t e r o f t h e e r a s e d a r e a . A d i u s t t h e
height position of the erase head if necessary.
M a k e s u r e t h a t t h e e r a s e h e a d d o e s n o t e r a s e a n y
part of the neighbour track. Ref . chapter 5.4.4 for
l a t e r a l a d i u s t m e n t .
7 . R e f . c h a p i e r s 5 . 7 . 1 I a n d 5 . 7 .
. I 0
f o r s e t t i n q o f t h e
b i a s a n d t h e r e c o r d i n g c u r r e n t .
5.3.2 The model l2-2
A l l t h e a l i g n m e n t s s p e c i f i e d i n c h a p t e r 5 . 3 . 1 a r e v a l i d
for the model i 2-2 with the exeption of the para-
g r a p h s 3 a n d 6 . P a r a g r a p h 3 i s s u p e r c e d e d b y t h e
i n s t r u c t i o n 5 . 6 . 2 , a n d p a r a g r a p h 6 i s s u p e r c e d e d b y
t h e i n s t r u c t i o n 5 . 6 . 1 .
6 .
G
5.4 HEAD ATIGNMENT
W I T H O U T TANDBERG TEST TAPES
5.4.1 Demagnetizing
Demagnetize fhe heads and adiacents parts before
a l i g n i n g t h e h e a d s .
5.4.2 The adiustable fape guides
R e f . f i g . I l .
T h e a d i u s t a b l e t a p e g u i d e 7 9 . 1 5 :
Move the operating lever fo normal forward drive
w i t h a t i g h f t a p e i n s e r t e d . A l i g n t h e v e r t i c a l p o s i l i o n
o f t h e a d i u s t a b l e t a p e g u i d e ( 7 9 . 1 5 ) u n r i l t h e t a p e
r u n s e q u i d i s t a n t f r o m t h e f l a n g e s o f t h e t a p e g u i d e .
T h e a d i u s t a b l e t a p e g u i d e 7 9 . 3 1 :
M o v e t h e o p e r a t i n g l e v e r t o n o r m a l f o r w a r d d r i v e w i t h
a t i g h t t a p e i n s e r t e d . A l i g n t h e v e r t i c a l p o s i t i o n o f t h e
a d j u s t a b l e t a p e g u i d e ( 7 9 . 3 . l ) u n t i l t h e t a p e r u n s e q u i -
d i s t a n t f r o m t h e f l a n g e s o f t h e t a p e g u i d e .
5.4.3 The record/playback head
T h e h e i g h t a l i g n m e n t :
T h e h e i g h t o f t h e r e c o r d / p l a y b a c k h e a d i s a l i g n e d b y
t h e h e i g h t a d i u s t m e n t s c r e w s , r e f . f i g . I i . T h e u p p e r
e d g e o f t h e t a p e s h a l l r u n f l u s h w i t h t h e u p p e r p a r t
o f t h e a i r g a p f o r c h . l . R e f . c h a p t e r s 5 . 5 . . t a n d 5 . 6 . 2 ,
for track control of the record/playback head.
T h e a z i m u t h a l i g n m e n t :
P l a y b a c k a s t a n d a r d a z i m u t h a l i g n m e n t t a p e w i t h a
VTVM connected to each external speaker output ter-
m i n a l . S e t t h e s p e a k e r s w i t c h t o p o s i t i o n u E x i r r . A d -
iust the position of the record/playback head by the
a z i m u t h a d j u s t m e n t s c r e w , r e f . f i g . I l , u n t i l m a x i m u m
r e a d i n g i s o b t a i n e d o n t h e o u t p u t m e t e r s .
T h e l a t e r a l a l i g n m e n t :
P u l l t h e p r e s s u r e p a d a w a y f r o m t h e e r a s u r e h e a d
w h e n t h e s t a n d a r d a z i m u t h a l i g n m e n t t a p e i s b e i n g
played back. The output level should noi decrease
m o r e t h a n 3 d B . A d i u s t t h e l a t e r a l p o s i t i o n o f t h e r e -
c o r d / p l a y b a c k h e a d , i f n e c e s s a r y , b y t u r n i n g t h e h e a d
m o u n t i n g p l a t e .
5.4.4 The erase head
T h e h e i g h t a l i g n m e n t :
T h e h e i g h t o f t h e e r a s e h e a d i s a l i g n e d b y t h e h e i g h t
a d i u s t m e n t s c r e w s . R e f . f i g . l l . A p p r o x . 0 . 2 5 m m
(.0 l") of the ferrite core for the upper track of the
e r a s e h e a d , s h o u l d b e v i s i b l e a b o v e t h e t a p e . R e f .
c h a p t e r s 5 . 5 . 2 a n d 5 . 6 . i , f o r t r a c k c o n t r o l o f t h e e r a s e
h e a d .
T h e a z i m u t h a l i g n m e n t :
A l i g n t h e a z i m u t h p o s i t i o n o f t h e e r a s e h e a d b y t h e
a z i m u t h a d i u s t m e n t s c r e w . T h e e r a s e h e a d s h o u i d b e
p a r a l l e l t o t h e u p p e r m o u n t i n g p l a t e . T h e a z i m u t h
p o s i t i o n o f t h e e r a s e h e a d i s n o t c r i t i c a l .
T h e l a t e r a l a l i g n m e n t :
T u r n t h e h e a d m o u n t i n g p l a t e f o r t h e e r a s e h e a d u n t i l
t h e f r o n t o f t h e h e a d i s p a r a l l e l t o t h e f e l t p r e s s u r e
p a d .
5.5
TRACK CONTROI, MODET I2-4
W I T H O U T TANDBERG TEST TAPES
5.5.1 The record/playback head
Record a
.|000
c/s signal in stereo from a generator
a t m a x i m u m r e c o r d i n g l e v e l , o n t r a c k j a n d 3 ( b o t h
f u n c t i o n s e l e c t o r s w i t c h e s i n < R E C O R D > p o s i t i o n ) , f o r
a p p r o x . 5 s e c o n d s . T u r n t h e t a p e a r o u n d a n d m a k e a
s i m i l a r r e c o r d i n g o n t r a c k 4 a n d 2 . C u t t h e f a p e a n d
d i p i t i n t o a m i x t u r e o f i r o n p o w d e r a n d a l c o h o l
(Magna-See) to make the recording visible. The spaces
between the recorded tracks should be distributed
e q u i d i s t a n i a c r o s s t h e t a p e . R e a d i u s t t h e h e i g h t p o s i -
t i o n , i f n e c e s s a r y , a n d r e c h e c k t h e a z i m u t h a l i g n m e n t .
5.5.2 The erase head
Insert a full-track pre-recorded tape and record a lO00
c / s s i g n a l f r o m a g e n e r a t o r a t m a x i m u m r e c o r d i n g
l e v e l o n t r a c k 3 ( t h e f u n c t i o n s e l e c t o r s w i t c h c h . 2 i n
( R E C O R D > p o s i t i o n ) . C u t t h e t a p e a n d d i p i t i n t o t h e
Magna-See solution. Check that the re-recorded irack
is in the center of the erased area. Adiust the vertical
position of the erase head, if necessary.
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