Watlow MLS - Manual (Page 121)

Troubleshooting
MLS User’s Guide 109
Troubleshooting
The next few sections describe general troubleshooting for the MLS.
Later sections describe specific procedures, like checking an input,
changing the EPROM, and testing the controller.
First, Check your Installation
The controller is only part of your control system. Often, what appears
to be a problem with the MLS is really a problem with other equipment,
so check these things first:
• Controller is installed correctly. (See Chapter 2: Installation for
help.)
• Inputs, like thermocouples and RTDs, are installed correctly with
correct scaling resistors, and working correctly.
Second, Replace Unit
WARNING
Check the installation before you replace the con-
troller! If the controller wasn't installed correctly,
for instance, if you have shorted sensor inputs to
high voltage lines or a transformer is shorted out,
and you replace the MLS with a spare unit, the
spare unit will break, and you'll need to send both
units to ANAFAZE for repair.
If you are certain that the controller is installed correctly, you can try
replacing the MLS with a spare controller -- one module at a time. If the
spare unit works correctly, then the problem is specific to the MLS you
replaced.
If you need to update the MLS Erasable Programmable Read-Only
Memory (EPROM), please refer to the third section, Changing the
EPROM.
Manual Controller Reset
If the instructions in this chapter tell you to perform a "manual
controller reset" (also called a "No Key Reset"), follow these
instructions:
• Disconnect power to the unit.
• Press and hold the No key on the MLS front panel. Reconnect power
to the unit.