Table of Contents
Advertisement
-
-
Runout Switch
The runout switch is provided but not used on this recorder.
Fail-Safe Brakes
For certain applications. it is desirable to include self-energizing mechanical
brakes on the transport to prevent a tape spill if power fails
.
The fail-safe brakes,
which are provided on special order, are released whenever power is on and are
applied when the machine is turned off or power interrupted.
Solenoid L6 is ener
gized directly from the low-voltage dc supply.
When it operates to lift the brakes
.
microswitch SIS is opened, inserting ISO-ohm resistor R73 into its path to prevent
overheating of the solenoid winding
.
SIGNAL ELECTRONICS FUNCTIONS
Signal electronics consist of record amplifiers, which raise the input sign..l
to a level required by the record (heads), a bias and erase frequency power supply,
and equalizer circuits and amplifiers to reproduce the signal recovered by the play
back heads
Each complete electronics assembly includes a power supply and
controls.
Signal processing is in conformance to NAB standards
.
The overdub
feature allows a record head to be used as a playback head so that a second track
can be recorded in synchronism with a pre-recorded signal.
This feature avoids
the time lag that would occur if the playback head were to be used for monitoring
during overdub operation
.
NAB ELECTRONICS
One electronics module is employed for each compatible NAB equalized track.
Thus, in a 1 /2-inch machine having standard four track heads four channels of NAB
equalized signals may be recorded
.
In this case four electronic assemblies are re
quired, equipped with the proper board for NAB service.
The following describes
the operation of a complete electronics assembly arranged for NAB service.
The individual plug-in boards will be fully described after an outline of their
function in relation to their service in the overall operation.
Refer to figures 31
and 32 during the following discussion.
The rectangular dashed areas represent
plug-in units
.
The numbers in ovals represent connector pin numbers.
NAI Recording
The signal to be recorded is applied through connector JI0l to the primary
of transformer T 1, which reflects an impedance of 20,000 ohms to the signal source.
Input is through a two-wire shielded cable with the signal lines ungrounded.
The
secondary of Tl is connected across RECORD LEVEL control RI00, which
establishes the level of the signal applied to the record amplifier
.
This amplifier
M64 PAR 2-71
_
_ _ _
_ _
••
_ _
_
. - : - - -
_
_
_ _ •
_
_ _
_
_ _ _ _
_ _ _
_ _ _ _
0 -
_
_
_ _ _ _
_ _ •
• _
-. _ .
_
_
_
• •
_
_
-
- . . . . - -
-
-
.- - - . .
.-
•
. . . . - - .
-
.
-
-
.
~
"
'
:
'
-
-
-
-
-
.
-
~
_
~
~
~
.
.
.
.
.
.
.
.
_
.
"
.
-
....
~
_
85
Advertisement
Table of Contents
