8
output signal to this video; otherwise the LTC generator free runs at an approximate 29.97 frames-per-second rate.
Generator Run/Stop
Each time the mode switch is momentarily positioned to SET and then released back to GEN LTC, the VLR-100 alternately
starts and stops incrementing the LTC numbers. When the generator is incrementing, the LTC colon LED blinks rapidly. When
stopped, the LTC colon LED blinks at a ¼-second on/off rate.
Presetting the Time Code
The VLR-100 LTC Generator starting value is preset using the MODE switch. When the MODE switch is held in the SET
position for two seconds, the minute, second and frame digits are preset to 00 while the hour digits flash the current hours value
on and off. Alternate activation/release of the MODE switch to/from the SET position causes the hour digits to count up to 23
and then start over at 00. The MODE switch can also be held in the SET position to force automatic counting of the hour digits.
Once the MODE switch has remained released from its SET position for two seconds, the preset operation moves to the minute
digits. Starting from 00 the minute digits can be counted up to 59 in a similar manner as the hours. Once the MODE switch
remains released from its SET position for two seconds, the minutes preset operation finishes. If no counting of the minute
digits is performed (i.e., MODE was never pressed to SET), the minute digits simply flash on and off for two seconds and then
the operation completes, leaving the minutes value at 00.
Except for jamsync and auto-backtime operations (both described further on), the seconds and frames are always preset to 00.
After presetting the minutes, the preset operation moves on to selection of drop frame or non-drop frame time code generation
indicated by the DF LED blinking on and off. Alternating the MODE switch to/from the SET position toggles between drop and
non-drop frame generation, forcing the DF LED on or off, respectively. Once the MODE switch has remained inactive for one
second, the drop frame preset operation completes.
At this point, the LTC colon LED begins to blink, indicating that the LTC generator is ready to run.
Presetting the User Bits
When the DATA switch is in the UB position, the user bits can be preset in much the same manner as used for presetting the
time code. Presetting the user bits does not affect the time code value. When the MODE switch is held in the SET position for
one second, the left most user bit digit blinks on and off, and can be preset to any value between 0 through 9 and A, B, C, D, E
and F, starting from its current value. Once the MODE switch remains inactive for one second, the preset operation moves on to
the next user bit digit until all eight have been given the opportunity to be preset.
If you wish to "auto-clear" all of the user bit digits before setting them (without affecting the time code value), continue to hold
the MODE switch in the SET position for one additional second after the left most digit first begins blinking.
Ending the Preset Cycle
If left on its own, the VLR-100 automatically ends the preset operation after several seconds. However, the preset operation can
be manually terminated at any time by switching the DATA switch between its TC and UB positions. Any time code or user bit
values you have preset so far remain in effect, and operation proceeds directly to starting the generator.
Automatic Backtime Preset
On a record master tape that is pre-striped with time code and black burst (or color bars and then black burst), it is often
desirable to have a "leader" of 30, 60, or more seconds before the time code number "rolls through zero" and the first edit is
performed. Performing the first edit at time zero allows the time code number to indicate the length of the program in addition
to the location of edits.
Automatic backtime preset allows the generator to be preset to a starting time "in front of" zero. The backtime preset value can
be selected from -30, -60, -90, or -120 seconds.
If the MODE switch is held in its SET position while the VLR-100 is powered up, the automatic backtime preset selection mode
is immediately entered. As long as MODE remains in the SET position, the display will sequentially change between
00:00:30:00, 00:01:00:00, 00:01:30:00, and 00:02:00:00, once per second. The time last displayed when the MODE switch is
released from the SET position becomes the amount of time automatically subtracted from the generator's start time whenever it
is preset.
For example, the VLR-100 LTC generator normally starts at 00:00:00:00 at power up. If automatic backtime mode is set to
00:00:30:00 (30 seconds), then the generator presets to 23:59:30:00. The automatic backtime mode remains in effect until the