Function Of T E S T P O I N T S - Tandy 1000 SL Technical Reference Manual

Function of T e s t P o i n t s
TP4 o r 5
(Pre-amp. o u t p u t )
2-3-1,
(1)
Index b u r s t delay
.:
-
Eight t e s t p o i n t s (one f o r DC OV) a r e equipped on t h e PCBA M F D c o n t r o l
f o r t h e check and adjustment o f t h e waveforms of t h e
F D D .
T P 1 ( I n d e x )
T e s t p o i n t to observe t h e o u t p u t of t h e index s e n s o r ( p h o t o - t r a n s i s t o r ) .
When t h e index h o l e i s d e t e c t e d , n e g a t i v e going p u l s e
i s
observed.
The p h o t o - t r a n s i s t o r i s mounted on t h e PCBA f r o n t OPT and t h e LED
i s
mounted on t h e DD motor A s s ' y ( s p i n d l e m o t o r ) .
TP1 i s used f o r t h e following purposes.
( a ) Confirmation of t h e d i s k r o t a t i o n a l speed.
(b) Rough confirmation and adjustment of t h e index b u r s t d e t e c t i o n timing.
B u r s t timing i s a d j u s t e d by t h e f i x i n g s c r e w s of t h e
PCBA
f r o n t
OPT.
(Use INDEX i n t e r f a c e s i g n a l f o r p r e c i s e confirmation and adjustment)
.
TP 1
(
Index)
U
U
U
Index
i n t e r v a l
L
Pulse width
( F i g . 2 1 4 ) Typical waveform o f TP1 (Speed o b s e r v a t i o n )
(Fig.215) Typical waveform o f TP1
(Rough o b s e r v a t i o n o f b u r s t timing)
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2 4 8
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