ST-47 Groundhog - Technical Manual
Servicing the ST-47
Page 16.
5.6 Troubleshooting Models with Deadman Capability
5.6.1 General
Before proceeding with this section the ST-47 must be operational. It must permit (green lamp)
when connected to a Scully Ground Ball or Ground Bolt. The unit is capable of turning on the green
permit lamp even if the deadman circuitry is not functioning properly. If the unit will not permit,
consult the earlier parts of this troubleshooting section for advice on repairing the problem.
5.6.2 Wire-Through and Stand-Alone Applications Troubleshooting
Problem: The ST-47 permit lamp comes on but the ST-47 will not activate an external device when
the deadman handle is operated. Turn off the power to the ST-47 by turning the Bypass switch to
the OFF position (if the unit has this option) or turn power off at the source. Using the correct
socket or hex wrench (depends on ST-47 date of manufacture) remove the cover fasteners and
open the front cover. Remove the fuse from its holder which is located at the right end of TB-1 by
turning the top on the right. Remove the now exposed glass fuse from the holder and check it with
a multi-meter set to the Ohms position. Do not rely on a visual inspection as a test for the fuse.
Is the fuse blown?
NOYES
The external device or wiring to it may be
shorted. Replace fuse, power-up system
and retest. If fuse continues to blow then
check for shorts in the output control wire to
device. Repair the problem, replace the fuse
with one that is the same rating and retest.
Replace the fuse in the holder and turn on the
power to the ST-47. With the cover of the ST-47
open, locate TB3 which is the two terminal strip
at the bottom of the explosion proof housing.
Using a jumper wire, short the two terminals
together. If the external device now operates.
There is a problem with the deadman switch or
the wiring to it. Repair the problem. If the ST-47
still does not permit, there could be a problem
with the I.S. Barrier relay that is located on the
inside front cover of unit. Consult the Scully
Service Department.
To Next Page
Loading...
Need help?
General