Overload Thermostat; Starting Current Limit Potentiometer; Overload Trip Indicating Light - Hobart GPU-600 Operation And Maintenance Manual

OM-2010

(2) Overload trip indicating light

More than 31.5 V DC output or overcurrent trips overload trip light DS2. The light emitting diode
circuit resets when S1 power on switch is cycled off and back on after the cause of the trip has
been removed. The LED light does not fail in normal use. Applying reverse voltage or overvoltage
to it during a test would be a more probable cause for failure, therefore applying a direct test is
not recommended. A bad light does not come on during a trip.
C. Overload Thermostat
The S5 overload thermostat must be closed in order for the DS2 overload light not to be on during
equipment turn-on. If AC power input is disconnected, verify continuity exists between the two S5
terminals with the leads to one of the terminals disconnected. Replace the S5 thermostat if the
wiring terminals on the S5 thermostat are not shorted.
D. Starting Current Limit Potentiometer
If the R13 starting current control has no effect on the output current above 250 A DC, check the
integrity of the R13 potentiometer before replacing the solid state control board. With input power
off and the R13 potentiometer slider terminal disconnected from the wiring, the resistance to the
slider terminal from each end of the potentiometer should change smoothly as the knob is turned.
If not, replace the potentiometer and retest. If retesting shows no change, the printed circuit con-
trol board is probably faulty also.
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April 10/89 Revised