Power Supply Module; Halogen Light Transformer(S); Convection Fan Motor; Bake Element (Upper Oven) - Bosch HBL8 50UC Series Service Manual

the module bracket from the 3 slots in the chassis.
Always reset the oven and test after changing the control module. In
some cases, a second reset may be necessary.
4.10

Power Supply Module

The power supply module (9.6V 12.5W) provides DC voltage to the
control module and user interface.
4.11

Halogen Light Transformer(s)

One transformer (120V-12V 40VA) is utilized per cavity. Triac
switches 120 VAC to the transformer. There are 4 terminals on the
new transformer, as shown in Figure 16.
The resistance between the primary terminals should measure ~12.8
ohms and the resistance between the secondary terminals should
measure ~0.32 ohms.
X105-6
BN
X205-4
LINE
Terminal
WH
Block
Figure 17 Halogen light transformer
Secondary
LINE
Terminals
Primary
LOAD
Terminal
OR
LOAD
OR
4.12

Convection Fan Motor

The convection fan motor is 120V 29W. To test the motor, check for
120V across X105 / Pin 2 (upper/single) or X205 / Pin 1 (HBL8650)
and chassis ground or neutral.
The motor is accessible from the rear, after removing the rear outer
sheet metal panel.
1. Disconnect the 2 wires from the motor terminals.
2. Remove 3 T20 screws from the arms of the motor assembly.
3. Use a tap and a hammer to dislodge the assembly from the
clips that secure it to the rear of the unit. (Position tap on the
arm secured by the rightmost clip.)
4.13

Bake Element (Upper Oven)

Refer to the Strip Element Diagram to test the element (240V 2000W)
at the control module, or disconnect the wires from the terminals and
use a meter to check for a reading of ~29 ohms.
To clear a path for removing the bake element, it is necessary to
remove the vertical air channel(s) and disconnect wires. Before
proceeding, note the position of the wires.
4.13.1

Removing the Bake Element

1.
Pull wires out of plastic purse locks attached to upper and
lower vertical air channels.
2.
Remove upper air channel (4 T20 screws).
3.
To create a pathway for the bake element, disconnect OR
wires from upper and lower bake element terminals; YE from
convection element terminals, BU/WH, BU, and WH from
cooling fan motor.
4.
Drape the wires/harnesses to the side so they do not block the
element as it is pulled out.
5.
Remove the screw between the element terminals.
Service Manual for Bosch Built-in Wall Ovens
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