Tandy 1000 SL Technical Reference Manual page 451

3-4-10. Check
of
Read Level
( A )
EQuipment
(1)
Level d i s k
(21
SKA
o r u s e r ' s system
(3) O s c i l l o s c o p e ( n o t r e q u i r e d when an SKA i s used)
(a-11
Check procedure (General method)
(1)
U s e two channels o f an o s c i l l o s c o p e and connect them t o
TP7
and TP8
( D i f f e r e n t i a t i o n amp.) on t h e PCBA MFD c o n t r o l .
O s c i l l o s c o p e range:
AC
m d e , 0.2
'L
0.5V
S e t both channels, 1 and 2 t o t h e above range. S e t e i t h e r o f t h e
channels t o I n v e r t mode and Add both channels.
( 2 ) I n s t a l l a l e v e l d i s k and s t a r t t h e s p i n d l e motor.
( 3 ) S e t t h e head t o t h e innermost t r a c k .
(4) Execute t h e head l o a d i n g .
(5) Execute 2F w r i t e o p e r a t i o n f o r one r o t a t i o n o f t h e d i s k (250KHz of
WRITE D A T A frequency f o r FD-55BR/FR and 500KHz f o r FD-55GR).
(6) Measure t h e average amplitude
(Vp-p)
o f t h e read waveform a s i n
Fig. 3416.
(7) C a l c u l a t e t h e read l e v e l by s u b s t i t u t i n g t h e following e x p r e s s i o n
with
t h e measured v a l u e i n i t e m (6) and READ
LEVEL c a l i b r a t i o n value
( s e e l e v e l d i s k l a b e l ) .
Read l e v e l (True v a l u e ) = Measured v a l u e x
100
C a l i b r a t i o n v a l u e
('I
-
3439
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