Teac A-6010GSL - Tape Speed; Set MONITOR

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SPECIAL CIRCUIT
PHASE SENSING CIRCUIT SYSTEM
The phase sensing reverse utilizes a separate amplifier located on
the bottom of the A-6010GSL transport section.
When the SIGNAL RECORD and ( p> ) buttons are depressed, the AC line
frequency (50 or 60 Hz) signal is recorded on the tape at a level of
approximately +4°10dB. This signal, however, is recorded out of
phase between the left and right channels since one of the record
head poles is electrically reversed during this mode. During play-
back with the AUTO REVERSE switch ON position, the record heads act
as the sensing device and are connected out of phase as they were
during the recording of the reversing signal.
Because the heads are now out of phase in respect to the normal audio
signals they generate very little or no output since the signals tend
to cancel each other out. However, when the previously recorded, out
of phase, reversing signal reaches the recording head. it is now in
phase in respect to the record head and generates a signal which is
amplified, rectified and utilized to energize the reverse relay.
It is feasible that a strong signal with no counterpart on the other
channel to cancel it out could cause the recorder to reverse. .How~
ever, proper adjustment of the reversing amplifier sensitivity
control will eliminate this possibility.
It must be understood that the reversing signal is recorded at such
a high level that normal signals do not approach this level.
Phase Sensing System Adjustments:
1. Thread a blank tape Scotch 203 on the recorder and set MONITOR
switch to TAPE, TAPE SPEED switch to 3~3/4ips.
2. Place the MODE L-R switches in the UP position.
3. Place the AUTO REVERSE switch in the ON position and set VR-1 to
full counter clockwise.
4. Depress the SIGNAL RECORD and the ( p> ) button for approximately
2 seconds.
5. Rewind the tape to the start of the recorded signal and press the
( p> ) button.
6. While playback this signal, advance VR-1 until the recorder stops
and reverses operation.
7. Rewind the tape once more and check to see if the recorder stops
and reverses, then increase the sensitivity of VR-1 slightly.
1
—Fig. 7-13 Location of PS Amplifier
7-14