Videotek TVM-821D, Service And Instruction Manual, Page: 9 / 29

Audio Level Switch Position
0 dBm
+4 dBm
+8 dBm
+12 dBm
0
1
2
3
BOTTOM OF UNIT
FRONT OF UNIT
TVM-851 PC BOARD
AUDIO REF.
LEVEL (SW1)
TRACE ROTATION
POT (R229)
9
Installation Instructions
POWER REQUIREMENTS
The TVM-821D can be operated at either 115V/60 Hz or 230V/50
Hz. No external selection has to be made in order to change the in-
put voltage. If it becomes necessary to replace the fuse, make
sure to adhere to the proper fuse value.
RACK MOUNTING
The metal cabinet (SSC-1) for the TVM-821D provides the proper
electrical environment for the instrument, limits the handling dam-
age, and reduces dust collection. Two #8-32 screws are provided
to secure the unit into the metal cabinet (they are installed in the
rear of the unit).
COOLING OF THE TVM-821D
The TVM-821D is cooled by an exhaust fan at the rear of the unit.
For proper air circulation, a minimum of 1.75 inches should be
maintained above and below the unit. Care should be taken not to
block the exhaust fan at the rear of the unit.
CUSTOM INSTALLATION
All installations must provide adequate ventilation and mechanical
protection. Top openings should not exceed 0.15 inches in diame-
ter. Other openings should not exceed 0.45 inches in diameter pro-
vided the circuits are at least 0.6 inches from the surface of the en-
closure. All conductive parts must be connected to the frame or
ground.
AUDIO LEVEL SELECTION
An internal rotary switch is provided to select the nominal audio in-
put level. This selection will provide the required attenuation for the
audio display. Factory setting is +4 dBm.
Adjust audio reference level rotary switch (SW1) located on bottom
of TVM-821D (see diagram below). Settings are per following
chart:
TRACE ROTATION
Before installing the unit in its final location, check the trace rota-
tion. The unit, like any other CRT device, is affected by the earth's
magnetic field. The trace might be rotated relative to the etched
graticule, depending upon the position of the instrument. Place the
unit in its final location and use H POS and V POS to position a
horizontal trace relative to the 0 mV line of the graticule. Adjust pot
R229 to align horizontal trace with graticule.