Epson QX-10 Technical Manual page 54

Test point
TP 1
TP 2/TP 3
Video amplifier outputs
TP 4/TP 5
Differential amplifier
outputs
TP
6
TP7
Index
TP8
Drive select
Function
A
zero volt line of the signal channel. Used as a reference point in observation of sig-
nal waveforms ofTP2 - TP7.
Test points for observing the video amplifier
(J.JA
733) outputs. the video amplifier
has two outputs: one is displaced 180 in phase (differential) and the other is
1
OOmVp-p or greater. Each output can be observed at TP 2 and TP 3.
These test points are used for checking the read/write head characteristics and
adjustment of the head access mechanism (off-track and azimuth).
Test points for observing the differential amplifier outputs. Like the video amplifier,
the differentail amplifier has two outputs:one is displaced
180·
in phase (differential)
and the other is greater than about 500mVp-p. Each output can be observed at TP4
and TP5. These test points are used for general checking of the read/write head and
amplifier and adjustment of the head access mechanism.
Apply a false index signal to this test point when the main PCB is checked as a single
body. Not used for adjustment and inspection.
A test point for observing the index detection output. Indicates the level inverse to
the index output signal and.is set to high level while the index hole is being detected.
This test point is used for checking the disc speed period and trigger signals for sig
nal observation of off-track, azimuth, etc.
Jl_-----'n ____ _
A test .... \(')int for observing a drive select signal. Set to low level when a drive select
signal i!:i transmitted from the host controller to the FDD.
Not selected
Selected
Table 3-2
3-3