Thermal Arc ULTIMA 150, Service Manual

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Manual 0-2503 37 SECTION 4: REPAIRS & REPLACEMENT
T1
T2
Socket Head Cap Screw
& Lock Washer
Phillips Head Screw &
Star Washer
Socket Head Cap
Screw & Lock Washer
A-01319
Figure 4-16 Model "B" Diode Bridge Assembly
(top view)
7. Remove the Diode Bridge Assembly and Thermal
Pad.
8. Clean bottom of Heatsink with a clean soft cloth
and isopropyl alcohol and place Thermal Pad on
Heatsink.
NOTE
Use new screws supplied with new Diode Bridge
Assembly. Do not reuse old screws.
9. Secure Heatsink as shown in Figure 4-16 above.
Torque all screws to 35 in- lbs.
10. Reconnect all cable connections as shown in Fig-
ure 4-14.
11. Replace Enclosure Cover.
E. Output PCB/Diode Bridge/Heatsink
Assembly Replacement
NOTE
These parts can be replaced as one assembly (See
Section 5.04, Parts Lists, for replacement parts.
1. Remove the Enclosure Cover per Section 4.04.
2. Locate the Output PCB/Diode Bridge/Heatsink
Assembly on the left side internal frame, as
viewed from the front of the unit.
3. Note the location of all the cable connections to
the Assembly.
J2
J1
J1
J1
A-01568
screws securing
PC Board to
frame
Transformer
Leads
Figure 4-17 Output PCB/Heatsink/Diode Bridge
Assembly
4. Carefully remove all the cable connections to the
Assembly.
NOTE
Be extremely careful when removing the 2 trans-
former leads from the Current Sense Toroids. Ex-
cessive force could damage the Toroids.
5. Remove the 4 Phillips head screws, one each cor-
ner, that secure the Output PC Board Assembly
to the frame.
NOTE
Do not remove the 4 screws with lock washers lo-
cated towards the center of the PCB. This will cause
the Heatsink (attached to the backside of the PCB)
to fall off.
6. Slide the Output PCB/Diode Bridge/Heatsink
Assembly out of the unit.
7. Install the replacement PCB/Diode Bridge/Heat-
sink Assembly by reversing the above steps.