J2 – Counter Select
The standard setting (pins 1 and 2 connected with a jumper)
enables the counter section. During normal operation, the
counter is used to determine switch timing. The counter
should be used with any signal that contains horizontal sync
pulses, such as NTSC, RGB with sync on Green, and similar
signals. During normal operation, if the sync input signal
does not have a horizontal sync component, the counter has
no effect. If a manually selectable time delay is needed (use
J1 and TR-1 to select and adjust the time delay) disable the
counter section. To disable the counter section, connect pins 2
and 3 of the J2 header with a jumper.
J3 – Enable Control
The standard setting (pins 1 and 2 connected with a jumper)
allows the CPU to control the enabling and disabling of the
sync board. Connecting pins 2 and 3 with a jumper discon-
nects CPU control and allows the board to be enabled
manually. Removing the jumper from the J3 header com-
pletely disables the sync board. J3 is used primarily for
testing, but there may be some applications that require ex-
ternal board enable control. The board is enabled when pin 2
is high, and disabled when pin 2 is low. Since pin 2 is pulled
to ground with a resistor, a switch connected between pins 2
and 3 controls board enable mechanically; or a TTL signal can
be placed on pin 2 to control board enable digitally.
4-5
Options
2
figure 4.5 Counter select on
2
figure 4.6 Counter select off
1
figure 4.3 Delay adjust
standard setting
1
figure 4.4 Potentiometer
setting
