Thermal Arc ULTIMA 150, Service Manual

Page: 42 / 64

SECTION 4: REPAIRS & REPLACEMENT 36 Manual 0-2503
D. Output Diode Bridge Assembly
Replacement
NOTE
The Ultima-150 has been manufactured using one
of two (2) models of Diode Bridge Assemblies - ei-
ther Model "A" or Model "B". Follow procedures
as they apply to your unit. All units with unit
serial number ending with a letter prior to "G"
are made with Model "A". All replacement Diode
Bridge Assemblies are Model "B".
1. Remove the Enclosure Cover per Section 4.04.
2. Locate the Diode Bridge 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 Diode Bridge Assembly. Figure 4-13 below
indicates the connections for Model "A" and Fig-
ure 4-14 shows the connections for Model "B".
Bus
Bar
OUTPUT PC BOARD
Current
Sense
Toroids
Transformer
Leads
E1
E2
T1
T2
A-01322
Figure 4-13 Connections for Model "A" Output
Diode Bridge Assembly
OUTPUT PC BOARD
Current
Sense
Toroids
Transformer
Leads
E1
E2
T1
T2
A-01321
Figure 4-14 Connections for Model "B" Output
Diode Bridge Assembly
4. Carefully remove all the cable connections to Out-
put Diode Bridge Assembly.
NOTE
Be extremely careful when handling the 2 trans-
former leads. Excessive force could damage the Tor-
oids.
5. Remove two (2) socket head cap screws and two
(2) lock washers on the Diode Bridge Assembly.
6. Remove the Phillips head screw and star washer
securing the Diode Bridge Assembly to the Heat-
sink.
Socket Head Cap Screw
& Lock Washer
Socket Head Cap Screw
& Lock Washer
Phillips Head Screw
& Star Washer
T2
T1
T3
A-01320
Figure 4-15 Model "A" Diode Bridge Assembly
(top view)