Microlok II System Startup, Troubleshooting, and Maintenance UNION SWITCH & SIGNAL
SM-6800C Rev. 2.5 September 2000 7-1
7. SYSTEM TROUBLESHOOTING AND RECOVERY
WARNING
FAILURE TO OBTAIN APPROVED TRAINING, AND TO ACT IN
ACCORDANCE WITH THE PROCEDURES AND WARNINGS OUTLINED IN
THESE MANUALS, MAY RESULT IN SERIOUS PERSONAL INJURY
AND/OR PROPERTY DAMAGE.
This chapter provides general guidelines for isolating and correcting Microlok II system
malfunctions. Troubleshooting any complex system such as Microlok II must follow a logical
approach that minimizes the time needed to isolate a fault or a series of related faults.
Troubleshooting the Microlok II system involves careful analysis of observable symptoms, a
knowledge of Microlok II system operation, and the ability to perform standard electrical and
electronic troubleshooting operations.
7.1 ISOLATING THE MALFUNCTION
The following is a general process recommended by US&S for isolating most Microlok II system
malfunctions.
1. If available, review the trouble report from the maintenance department or the central
office to define the circumstances associated with the problem. Define:
a. When the malfunction occurred.
b. The condition of the system at the time of the malfunction.
c. The location of any trains in or near the interlocking when the malfunction occurred.
2. Scan the Microlok II system indications for any obvious clues that might lead to a quick
diagnosis of the problem. Check the following:
a. The power supply board 5
V ON indicator LED should be on.
b. The power supply board
VCOR LED should be illuminated.
c. The CPU board
ON-LINE LED should be on.
d. The CPU board
VPP LED should be off.
e. The RESET LED should be off.
f. The CPU upper 4-character display should be scrolling the phrase
US&S MICROLOK II.
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