TROUBLESHOOTING
4-18
Manual 0-2972
2.
Measure for approximately 28 VAC on coil of Con-
tactor between wires #11 and #12.
• If voltage is correct, replace Main Contactor. If
voltage is incorrect, replace Main PC Board.
F. Gas Solenoid Circuit Test
Make the following voltage checks and replace the faulty
part as required.
1.
Place the RUN/RAPID AUTO RESTART/SET
Switch to the SET position.
2.
Measure for 28VAC across Solenoid wires #7 and
#8.
• If 28VAC is present, replace Solenoid/Pressure
Switch Assembly. If 28VAC is not present, go to
the next step.
3.
Check voltage at J1-14 to TP1 on Logic Board.
• If less than 2vdc replace Main Power PC Board.
If more than 2vdc, replace Logic PC Board.
G. IGBT Board/Output Diode Circuit Test
1. No DC Output
When the unit is at “idle” the AC indicator on the
Front Panel should be ON. When the torch is acti-
vated, the gas begins to flow. When the preflow time is
over, the INV ON indicator on the Logic PCB energizes,
and the DC indicator on the Front Panel turns ON.
• If the INV ON indicator does not turn ON, then
replace the Logic PCB.
•
If the INV ON indicator turns ON then OFF imme-
diately, the following test should be performed:
a. Disconnect eight-pin wire harness connector
from the Pilot PC Board.
WARNING
The connector on the Pilot PC Board must be dis-
connected to prevent electrical damage to measur-
ing equipment when testing the open circuit volt-
age (OCV).
b. Activate torch (Logic PC Board Inverter On In-
dicator, turns ON).
c. Measure for more than 200 vdc between E7(+)
and E10 (-) on the Main PC Board. If voltage is
less than 10 vdc, each
IGBT Module and Out-
put Diode Module
should be tested individu-
ally.
2. Output Diode Circuit Test
WARNING
Disconnect primary power at the source before tak-
ing any resistance checks.
a.
Use an ohmmeter set to the diode function and make
the following measurements on the Output Diode
Board to Main Power PC Board.
Meter (+) Meter (-)
Indication
E18
E21
Diode Drop
E21
E18
Open
E18
E20
Diode Drop
E20
E18
Open
E20
E19
Diode Drop
E19
E20
Open
E21
E19
Diode Drop
E19
E21
Open
E18
E19
(2) Diode Drops
E19
E18
Open
b.
The meter should indicate a diode drop in one di-
rection and an open in the other direction for each
check. Replace Output Diode Board if readings are
not the same as the chart.
