Teac MT-20D-IO Maintenance Manual page 89

3-7-2 Functions of variable resistors
The PCBA Drive Control and PCBA Interface Control are provided with variable
resistors for various adjustments.
(1) R21. 17 (adjustment of read preamplifier
lev~l)
PCBA Drive Control
R21 and R17 are variable resistors to adjust the levels of the read
amplifiers for the track 0/2 and track 1/3. respectively.
While monitoring the read amplifier levels. adjust R21 and R17 until
they become the specified values.
(2) R48 (adjustment of read level) PCBA Drive Control
Variable resistor for adjusting the read level.
While monitoring the read level at TP8. adjust R48 until it becomes
the specified value.
(3) R41 (adjustment of hole sensor sensitivity) PCBA Drive Control
Variable resistor for adjusting the sensitivity of the hole sensor.
Adjust R41 until the voltage at TP13 becomes the specified value when
the hole sensor test tape is loaded.
(4) R44 (adjustment of 90 ips tape speed) PCBA Drive Control
Variable resistor for adjusting the tape speed of 90 ips. Adjust R44
until the frequency of ENC signal (J4-12) becomes the specified value
during tape movement at high speed (HIS signal at J4-26 is true).
(5) R43 (adjustment of 30 ips tape speed) PCBA Drive Control
Variable resistor for adjusting the tape speed of 30 ips.
Adjust R43 until the frequency of the ENC
sign~l
(J4-12) becomes the
specified value during tape movement at low speed (HIS signal at J4 -
26 is false).
At this time, it is necessary that the adjustment of R44 (90 ips tape
speed) has been completed prior to the adjustment of R43.
If R44 is adjusted later than R43. the 30 ips tape speed may also be
changed.
Remark
The 30 ips tape speed is fixed in some model of MTU. In
such a model, not a variable resistor but a fixed resistor
is mounted as R43.
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