Thermadyne Thermal Dynamics PAK MASTER 50XL, Service Manual

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SERVICE TROUBLESHOOTING 22 Manual 0-2587
OL
VR COM A
A-00306
Anode
Cathode
Reverse Bias
Diode Not Conducting
+
_
Testing Diode Reverse Bias
7. If a diode checks bad, replace the diode module.
8. Reconnect all cables to proper terminals.
D. Input PC Board Test
Check Input PC Board for shorted input diode.
R2
G (+) (-)
AC1 AC2 AC3
A-01402
Input PC Board
Remove AC power and with an ohmmeter set on the di-
ode range make the following checks:
Meter (+) Meter (-) Indication
AC1 R2 Diode Drop
R2 AC1 Open
AC2 R2 Diode Drop
R2 AC2 Open
AC3 R2 Diode Drop
R2 AC3 Open
AC1 (-) Open
(-) AC1 Diode Drop
AC2 (-) Open
(-) AC2 Diode Drop
AC3 (-) Open
(-) AC3 Diode Drop
The meter should indicate a diode drop in one direction
and an open in the other direction for each check.
If Input Bridge Diode is shorted, make the following
checks with an ohmmeter at the Main Contactor:
Meter (+) Meter (-) Indication
L1 T1 Open
L2 T2 Open
L3 T3 Open
If any test has resistance, then replace the Main Contac-
tor also.
E. Main Contactor (MC1) Test
Reconnect power and observe proper start-up procedure.
Indicator D34 on the Logic PC Board should be ON. If
indicator D34 is OFF there is no voltage to the Power
Supply or an overvoltage condition exists.
A-01395
Logic PC Board
D34