Tandy 1000 SL Technical Reference Manual page 330

TP4 and TP5 a r e used f o r checking v a r i o u s c h a r a c t e r i s t i c s o f t h e read/
w r i t e head and a l s o f o r t h e check and adjustment of t h e head seek
mechanism such a s t r a c k alignment.
2 . Sv,approx.
TP4, TP5
(Pre-amp
.
)
(Fig.218) Typical waveform o f TP4 and TP5
( 5 ) TP7, TP8 ( D i f f e r e n t i a t i o n a m p l i f i e r )
T e s t p o i n t s t o observe t h e d i f f e r e n t i a t i o n a m p l i f i e r o u t p u t s i g n a l s .
Like t h e p r e - a m p l i f i e r , t h e d i f f e r e n t i a t i o n a m p l i f i e r a l s o has two
o u t p u t s o f t h e o r d e r of s e v e r a l hundred mVp-p t o s e v e r a l Vp-p which
d i f f e r i n phase by 180". Both o u t p u t s a r e observed a t TP7 and TP8
r e s p e c t i v e l y .
For an a c c u r a t e o b s e r v a t i o n of t h e waveforms, use two channels of t h e
o s c i l l o s c o p e with one channel s e t t o I n v e r t mode and Add both channels.
Use TP6 ( O W t e s t p o i n t f o r t h e o s c i l l o s c o p e ground.
TP7 and TP8 a r e used f o r checking t h e t o t a l o p e r a t i o n o f t h e r e a d / w r i t e
head and t h e read a m p l i f i e r and f o r t h e check and adjustment of t h e head
seek mechanism such a s t r a c k alignment.
TP7, TP8 2.5v,
( D i f f e r e n t i a t o r ) J
approx.
(Fig.219) Typical waveform o f TP7 and TP8
( 6 ) TP6 (OV)
I t
i s
used a s t h e ground t e r m i n a l f o r measurement equipment. B e s u r e
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