Auto-Zone Control Systems Auto-Zone Basic Systems Installation & Operation (Version 02C) - Manual (Page 135)

Auto-Zone Basic Section 4
Start-Up & Troubleshooting 4-33
Communications Loop
Zone Manager
Test the communications loop with the system powered up. Set meter to read DC Volts.
These tests assume that if the optional CommLink IV is installed, it is also connected and
powered up. Actual meter readings may deviate slightly depending on the number of
units installed. Any significant deviation from these values generally indicates a problem.
If voltages are not within specified ranges, the Zone Manager communications driver
chip is likely damaged and will have to be replaced.
Step 1
Measure the voltage at the Zone Manager terminals with the Communications Loop con-
nected to the Zone Manager.
Basic System - Without Optional
CommLink Installed
Basic System - With Optional
CommLink Installed
Measure Voltage Measure Voltage
T to SHLD + 2.7 to 2.4 VDC T to SHLD + 3.1 to 2.9 VDC
R to SHLD + 2.6 to 2.3 VDC R to SHLD + 2.1 to 1.9 VDC
If the voltages are within the specified voltage ranges, the Zone Manager and communi-
cations loop are operating within specifications. If the measured voltages are not within
the specified voltage ranges, proceed to Step 2.
+ -
T
R
COMM
TB8
SHLD
+
-
+ -
T
R
COMM
TB8
+
SHLD
-
Measuring R to SHLD Measuring T to SHLD