Teac MT-20D-IO Maintenance Manual page 155

4-3-14 Check and adjustment of read preamplifier level
(1) Articles to be used
(a) Level test tape
(b) Conventional screw driver
(c) SOA
small size
(d) DC power supply (+12 V, +5 V)
(2) Check and adjustment procedures
(a) Connect SOA in accordance with Item 4-2-5, and set the POWER
switch to the PSA side (it is not required to connect a check
cable C).
(b) Erase the level test tape by the bulk eraser or erase the portion
of tape to be used for test over some length by using MTU.
(c) Load the erased level test tape on MTU.
(d) Wind the tape nearly in the winding center.
(e) Connect the oscilloscope to TP3 on the PCBA Drive Control.
(£) Key in "A22".
(g) Key in "A63F". Measure the signal level on the oscilloscope.
TP3
Signal level
Since the signal contains large noise, triger the
signal appropriately changing the triger level until
the picture shown in the above is obtained.
Fig. 432 Measurement of read preamplifier level
(h) Check if the signal level is within the range of -150 mV to
+150 mV for the calibrated value of the level test tape used.
Example
When the calibrated value is 250 mV, the abovementioned
range is from 100 mV to 400 mV.
(i) Key in "F" to stop the operation.
(j) Key in "A2l".
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