4
DRAFT
1. GENERAL DESCRIPTION
The MU Cable Tester System performs shorts testing, continuity testing, and ground-leakage testing for
each of the 27 Multi-Unit control lines normally found on freight locomotives. The MU Cable Tester
System can be used to test MU lines within the railcar as well as MU jumper cables connected to them.
The tester system is able to perform these tests on a locomotive consist of up to eight railcars while the
locomotive is powered up and stationary. MU jumper cables can also be tested individually.
A failsafe mechanism (Emergency Shut Off) is designed into the test system to immediately disconnect
the test units in the event that an unexpected movement of the locomotive occurs during testing. The
emergency shut off switch immediately removes testing signals from the MU control lines without
removing power from the test unit itself; the emergency shut off function can be accessed from either
the slave or master unit and disconnects both slave and master when activated.
1.1. System Components
The MU Cable Tester System is comprised of two identical tester units. Each unit is installed in a heavy
duty, water resistant, plastic Pelican case. Either unit can be designated as a Slave unit or a Master
Unit. Each unit contains an MU cable receptacle that mates with the typical railcar MU jumper cable. A
snap-on vinyl pouch on the outside cover of each unit provides storage for the battery charger/power
adapter and the chassis test lead. Every MU Cable Tester System contains two of the following:
1. MU Cable Tester Unit (16814-00)
2. AC Power Adapter (16944-01)
3. Chassis Test Lead (17034-01)
2. EQUIPMENT DESCRIPTION
The MU Cable Tester System is a complete, stand-alone tester for MU Jumper cables and MU control
lines found within freight locomotives. The test operator selects one test unit to be used as a slave and
the other as a master. Typical equipment configuration for the MU Cable Tester System is one
designated Slave unit connected to one designated Master unit by way of one MU jumper cable. Up to
eight railcars can be added between the slave and master units with nine jumper cables connecting the
entire chain. All MU railcar lines and MU jumper cables connected between the slave unit and master
unit will be tested as a group.
The enclosure cover-hinges separate from the test unit as the cover is opened; this removes the cover
completely to allow free access to the MU cable receptacle as well as operator test functions. The
control panel is mounted so the operator can typically view the display and operate the function buttons
from the side of the case. The emergency stop button is centrally located within the enclosure to allow
quick access from almost any location around the test unit.
The designated master unit activates the driving circuitry that switches a low-level signal onto each of
the train lines, one at a time. The designated slave unit completes the communication link required for
testing. Both MU Cable Tester units can be powered by the internal battery or the AC power adapter /
battery charger. In addition, the 72 volt locomotive battery provides battery charging through an isolated
charging circuit. This connection is disconnected while tests are being executed.
2.1. The Designated Slave Unit
The MU Cable Tester designated as the slave unit performs a self test when powered ON. After a
preliminary shorts test between conductors, the designated slave unit waits for a communication link
from the master unit. The slave unit monitors a preselected set of possible communication conductors
chosen from spare conductors. The slave unit responds to commands from the master unit after the
two-way communication link has been established.
16814-99 Rev. A
