Scully ST-47 Series User Manual

Servicing the ST-47
Self-Proving Vehicle Grounding Verication System
Page 15.
Procedure 2, Step A1
(Ground Bolt or Ground Ball NOT required) If you do not have a Scully Ground Bolt or Ground Ball.
Using a Multi-Meter set on DC volts measure the voltage between spring plunger contact inside the
plug (+) and one of the three contact ngers (-) of the Ground Ball Connector Plug.
Is the voltage between 24 and 30 volts DC?
Procedure 2, Step B
(Ground Bolt required) Using the correct socket or hex wrench (depends on ST-47 date of
manufacture) remove the cover fasteners and open the front cover. Using a at-blade screwdriver,
remove the wires on intrinsically-safe terminals TB2 and 3. Attach the green wire of the Ground Bolt
to TB2-3 and the top of the bolt (at the end of the threads) to TB2-2.
Does the ST-47 Permit?
Procedure 2, Step B1
Using the correct socket or hex wrench (depends on ST-47 date of manufacture) remove the cover
fasteners and open the front cover. Using a at-blade screwdriver, remove the wires on
intrinsically-safe terminals TB2 and 3. Using a Multi-Meter set on DC volts, measure the DC voltage
between terminals TB2-3 (+) and TB2 (-).
Is the voltage between 24 and 30 volts DC?
NOYES
Trailer grounding system could be at fault.
Have tank owner check the installation or,
contact the Scully Service Department for
assistance.
If the voltage is lower or zero- Using an open
end socket wrench, open the plug and cable
junction box. Remove line power to the ST-47.
Remove wires that come from the cable and are
connected to terminals 9 and 10. Power the
ST-47. Check the voltage at terminals 9 (+) and
10 (-) at the terminal block found inside. Power
the ST-47. If you now read 24 and 30 VDC at
terminals 9 and 10. There is a problem in the
cable or wiring to the overll plug. Correct the
problem. If the voltage is still below limits, go to
step B1.
NOYES
There is a problem between the ST-47 TB-2
terminals and the Junction Box terminals.
Correct the wiring problem.
The ST-47 circuit module is defective. Replace
the module with a new one or, return the board
to the Scully Signal Company for repair or
Warranty consideration.
NOYES
There is a problem between the ST-47 TB-2
terminals and the Junction Box terminals.
Correct the wiring problem.
The ST-47 circuit module is defective. Replace
the module with a new one or, return the board
to the Scully Signal Company for repair or
Warranty consideration.

Scully ST-47 Series Specifications

General

Brand	Scully
Model	ST-47 Series
Category	Control Unit
Language	English