Rack Control Module
TM
Product Manual
Rev. 1.2, May 9, 2014 Page 40
TD80 and RCM Intermittent Circuit Troubleshooting 4.3
Diagnosing and repairing a problem that comes and goes is one of the most challenging
situations to troubleshoot. Sometimes the problem only affects one part of a system or
seeming random things happen everywhere.
Where do you start?
Start by knowing your system; how it operates, what features and options are installed
and know that most problems are caused by wires. Broken wires, corroded wires, short
circuited wires and ones that sometimes make and then break a circuit can cause a
confusing collection of symptoms.
General guidelines for intermittent faults are listed below.
1. Visually inspect all wiring and interconnections for:
a. Broken, stretched or chaffed insulation.
b. Areas at terminal strips for loose connections and corrosion.
c. Places where wires have been joined by a crimp or solder connection.
d. Any place that is covered with electrical tape that appears to be a splice or
repair.
e. Water, frost, ice, heavy dust, metal particles or loose hardware inside
enclosures and junction boxes.
2. Observe all trouble indications
a. Does the problem always appear in the same way or does it change from
time-to-time?
3. Consider the history.
a. Was the system recently installed, repaired or modified?
b. Does this problem have a history of reappearing after repair?
4. Try to reproduce the problem.
a. Does the problem appear when the system is first turned on or after some
period of time?
b. Does the problem seem to be vibration related?
A useful technique is to inspect the system while it is operating and carefully wiggle,
slightly tug or bend wires where intermittent connections are most likely to occur. These
are at terminal strips, crimped or soldered connections, plug and sockets. Observe if the
problem repeatedly appears when one area of the wiring is moved.
Keep in mind that there may be more than one wiring problem if the situation is after an
installation or extensive repair.
Some common TD80, Finch and RCM indications are listed with suggested
troubleshooting and repair steps.
1. Finch display repeatedly cycles the display (0 thru 9, A thru F) and alarm tests.
a. Power is being interrupted:
i. Check all battery power and electrical ground connections to the
Finch display.
2. Finch display repeatedly shows “----“, indicating loss of communication with the TD80
transmitter.
a. Power, electrical ground or the SV Bus data between the Finch display and
TD80 transmitter is being interrupted:
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