Teac MT-20D-IO Maintenance Manual page 73

3-7-1 Functions of test points
The PCBA Drive Control and PCBA Interface Control are provided with the
following test points to facilitate observing the waveforms required during
MTU adjustment and test.
(1) TPl (GND) PCBA Drive Control
This point is connected to 0 V.
(2) TP3 (output of read preamplifier) PCBA Drive Control
Test point for measuring the output of the read preamplifier.
TP3 is used to adjust the level of the read preamplifier" ,and check
the various characteristics of the head Ass'y, etc.
Signal level: 200 to 600 mVp-p
Fig. 337 Example of waveform at TP1
(3) TP4 (6
V
bias) PCBA Drive Control
This test point is connected to the
6 V
bias power supply generated
within MTU.
TP4 is used to measure the various characteristics by using SOA
(Simulator OA).
(4) TP5 (AGC output) PCBA Drive Control
Test point for measuring the output of the AGC amplifier.
TP5 is used to check the operation of the AGe amplifier. Since TP5
is a test point used during manufacturing of MTU, it is not used for
maintenance usually.
- 361 -