7. When all the encoders in a transponder are reporting ENC faults for both the primary and secondary
communication pairs, each pair can be checked for transmission of the query word from the CPU by
using aTriplett 310 meter. This can be done by setting the meter on the 12VDC scale and placing the
black meter lead on the A line and the red meter lead on the B line. No deflection on the meter indi-
cates that the query word from the CPU is not being received. One or more distinct deflections every
few seconds indicates that the word is being received. Check one pair and then the other.
Note:
If
the meter deflects the wrong way, simply reverse the meter leads.
If all the encoders are reporting ENC faults for only one of the two communication pairs (either pri-
mary or secondary), you can assume that the encoders are operating properly. If this is the case, the
problem is probably in the communication pair that was reported with the ENC faults. Remove that
communication pair from the transponder terminals and check for the query word from the CPU.
8. A Simplex Line Tester (CPU Simulator) can be used to test transponder operation. A Diagnostic Ex-
ercisor is also available to help diagnose problems within a transponder.
Transponder Test Points
1. A reduced AC input voltage of 25 (e3) VAC can be measured at the motherboard’s terminal block be-
tween the terminals labeled AC.
2. A battery charging voltage of 27.5 (20.1) VDC can be measured at the motherboard’s terminal block
between the terminals labeled Battery + and Battery -.
3. 12 (k 0.3) VDC can be measured at the address jumper point (choose one that does not contain a jumper)
or on azone interface board between the +12 and GND terminals.
4. Approximately 27.5 VDC should be measured between “Battery Sense +” and “Battery -” on the mother-
board terminal block. Loss of power to the Battery Sense terminal will result in a Power Supply (P.S.)
fault message.
5. Batteries must be disconnected to be checked. The best place for this is the harness connector. You
should measure 24VDC (+3.0 or -1 .O).
6. When replacing PC boards,
power must be removed.
a.
Disconnect the batteries at the connector
on
the harness.
b.
Remove one of the AC fuses.
7. Test a transponder alarm point by tripping one that does not have excessive control-by-events. See
Transponder Specification Sheet to determine the priority of the alarm.
8. Test control points by using the (MAN) command.
575.531
9
Ed 8 82
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