D9124 Operation & Installation Manual
Page 56
© 1995- 1996 Radionics
74-06799-000-D 2/96
Problems with the D8125 POPEX Data Expansion Loops
EMI (Electro-Magnetic Interference), excessive resistance, or intermittent grounds,
shorts, or opens on the data expansion loop can cause erratic or intermittent functioning
of points. Follow the procedures below to find the source of problems on the data
expansion loop.
EMI
If you suspect EMI may be a problem, see
EMI on Long Wire Runs in this section.
AC induction on the data expansion loops must be less than 10 VAC.
Measuring Resistance on the Loops
Before you follow the procedures below to measure resistance on the data expansion
loops, check
Table 6 in the Zonex section to be sure you used the correct gauge wire for
the length of the data expansion loops. Be sure not to connect your meter leads to power
when measuring resistance. This may damage your meter.
When you measure the loop for resistance, monitor it long enough to observe an
intermittent problem.
To measure the resistance of the data expansion loop without POPITs connected
to it:
1.
Disconnect the loop from the motherboard.
2.
Twist the positive and then the negative wires together at each POPIT location so
that the positive and negative wires are continuous to the last POPIT location.
3.
At the last POPIT location twist the end of the positive wire to the negative wire to
form one continuous loop.
4.
Measure the loop for resistance from the point where it connects to the motherboard.
Resistance for the entire loop must be less than 60
Ω
. If there is no continuity, find
and repair the open on the loop.
5.
While still measuring for resistance, untwist the negative and positive wires at the last
POPIT location. If the meter does not show an open condition, find and repair the
short on the loop.
6.
Twist the positive and negative wires at the last POPIT location back together.
7.
Measure the loop for resistance to terminal 10 (earth ground). If there is a short to
ground, find and remove the foreign ground from the loop.
8.
Measurer the loop to terminal 10 for AC voltage. AC induction on data expansion
loops must be less than 2 VAC. Try using shielded cable to reduce AC induction if
the AC voltage exceeds 2 VAC.
www.PDF-Zoo.com
firealarmresources.com