Thermal Dynamics Pak Master 75XL Plus, Service Manual

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Manual 0-2747 4-11 TROUBLESHOOTING
If Input Bridge Diode is shorted, make the following
checks with an ohmmeter at the Main Contactor:
M e t e r (+ ) M e t e r (-) I n d ica t io n
L 1 T 1 O p e n
L 2 T 2 O p e n
L 3 T 3 O p e n
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.
With the ON/OFF Front Panel switch in the ON posi-
tion, the AC LED should be blinking. If AC LED is not
blinking, there is either no power tot he unit or an over-
voltage condition exists.
• Single Phase Units check at L1 and L2
• Three Phase Units check L1, L2, and L3
L1
L2
L3
Main Contactor
(MC1)
A-02671
Coil
Wire #59
Coil
Wire #55
Note: Not all MC1 wire
connections are shown
Measure voltage on coil of contactor, approximately 117
VAC between wires #70 and #75.
• If voltage is correct, replace Main Contactor.
• If voltage is incorrect, replace Logic PC Board.
F. Temperature Circuit Test
Test the temperature circuit per the following:
1. Place the front panel ON/OFF switch to the OFF
position.
2. Disconnect ribbon cable from the Upper FET/
Heatsink Assembly at J6.
A-01213
J6
FET/Heatsink and
Capacitor PC Board
Assembly
3. Place the front panel ON/OFF switch to ON.
4. Check status of the TEMP indicator. If indicator
has gone OFF, then remove power and replace the
FET/Heatsink Assemblies.
CAUTION
The FET / Heatsink Assemblies are matched and
balanced during production and must be replaced
in pairs.
5. Place the front panel ON/OFF switch to the OFF
position.
6. Disconnect ribbon cable from the Lower FET/
Heatsink Assembly at J6.
7. Place the front panel ON/OFF switch to ON.
8. Check status of the TEMP indicator. If indicator
has gone OFF, then remove power and replace the
FET/Heatsink Assemblies.
9. Place the front panel ON/OFF switch to the OFF
position.
10. Remove power from unit.
11. Disconnect connector from J2.