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power amplifier. If the sound box and the tone arm can not be isolated, howling phenomena is often
existed. There are some methods to deal with the above phenomena.
1
、
Adopt better directional tone arm.
2
、
Adjust the sound box volume to be under the threshold that produces the howling phenomena.
3
、
Use fitment materials that absorb the sound to reduce reflection of the sound.
4
、
Adjust the layout of the sound box and the tone arm.
2.7 Alarm input and output connections
Before connecting the device,please pay attention to follow situations:
*note: Some products have no alarm input/output functions.
１
.Alarm input
A.
Alarm input is grounding alarm input.
B.
Alarm input demand is the grounding voltage signal.
C.
When the alarm is connected with two
N
VRs or connected with
N
VR and other equipments, it
should be isolated by relay.
2.Alarm output
Alarm output can not be connected with high-power load(no more than 1A).When forming the output
loop it must prevent the big current from relay damage. Use the contact isolator when there is a
high-power load
3.PTZ decoder connections
A.
The
grounding
of
the
PTZ
decoder
and
N
VR
must
be
shared
otherwise
the
common-mode
voltage will lead to the PTZ control failure. The shielded twisted pair is recommended.
B. Avoid the entrance of high voltage. Make the layout reasonably. Take precaution from the
thunder.
C. In the outlying end connect 120Ω resistance paralleled to reduce the inflection and insure the
signal quality.
D.
The 485 AB lines of
N
VR can not connected with other 485 output equipments paralleled.
E. The voltage between the AB lines of the decoder must be less than 5V.
4.Front equipment grounding note
Bad grounding can lead to the burnout of the chip.
5.Alarm input type unlimited
