Thermal Dynamics Pak Master 75XL Plus, Service Manual

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Manual 0-2747 4-5 TROUBLESHOOTING
10. Faulty ON/OFF switch (refer to Appendix 10, 36 VAC
Circuit Diagram)
Measure for 36 VAC on the Logic/Gate PC Board
between J3-2 to J3-4.
a. If voltage is not present replace the ON/OFF
switch
11. Faulty ribbon cable
Refer to Appendix 10, 36 VAC Circuit Diagram
and check for continuity on the pins.
a. If any line between pins is open, replace the rib-
bon cable
b. If voltage is present, replace Logic/Gate PCB.
C. System will not pilot; AC indicator ON, TEMP
indicator ON
1. Air flow through unit is restricted
a. Provide adequate air flow (Refer to Operating
Manual 0-2746, Section 3.02)
2. Exceeded duty cycle of Power Supply
a. Wait for fans to cool unit and refer to Operat-
ing Manual 0-2746, Section 2.03, for proper
Duty Cycle.
3. Faulty Fan or Logic/Gate PC Board
Measure for 115 VAC on the Logic/Gate PC Board
from J2-2 to J2-8 and J2-3 to J2-9.
• If voltage is correct, replace Fan Assembly.
• If voltage is incorrect, replace Logic/Gate PC
Board.
4. Faulty temperature circuit
a. Check temperature circuit per Section 4.09-F;
repair as necessary
D. No gas flow; AC indicator ON; TEMP indicator
OFF; GAS and DC indicators OFF
1. RUN/SET/LATCH switch in RUN (or LATCH) posi-
tion
a. Switch to SET position.
2. Gas supply not connected to unit
a. Connect to gas supply.
3. Gas supply not turned on
a. Turn gas supply on.
4. Faulty RUN/SET/LATCH switch
a. Check continuity.
5. Faulty gas solenoid circuit
a. Test gas solenoid circuit per Section 4.09-G; re-
pair as necessary
E. Gas flows; Gas indicator OFF: AC indicator ON;
DC indicator OFF
1. Gas pressure too low
a. See torch manual for operating pressures.
2. Faulty pressure switch
Measure for DC voltage from wire #51 to wire #50
at the gas pressure switch at the rear of the Rear
Panel Assembly.
a. If 12vdc and pressure is above 50 PSI, replace
gas pressure switch.
Wire #51
Wire #50
Gas Pressure Switch
Rear Panel
Gas Solenoid
A-01184