Bosch HMB402 Service Manual page 19

COMPONENTS
RELAY 2
FAN MOTOR
(Wire leads removed)
TURNTABLE
MOTOR
(Wire leads removed)
SENSOR
NOTE : • A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED
WHEN THE UNIT IS SERVICED FOR ANY REASON.
• MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION.
• WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE
TO GRASP THE CONNECTOR, NOT THE WIRES.
F-code
When self-heating time of humidity sensor exceeds 64 seconds or
F-4
if zero balancing voltage does not rise to 2.5 [volt]
Only "CLEAR" key is permitted to enter.
TEST PROCEDURE
Check for continuity of relay 2 with an
ohm-meter.
(Remove wire leads from relay 2 and
operate the unit.)
Relay 2
Measure the resistance.
(Ohm-meter scale: R x 1)
Measure the resistance.
(Ohm-meter scale: R x 1 )
1) Disconnect sensor connector from
micom computer board.
2) Measure resistance terminal to terminal
(ohm meter scale: R X 1000)
BK
1
RD
2
3 WH
5-10
POWER
LEVEL
1
2
3
4
5
6
7
8
9
10
Normal:
A: Approx. 85 ~ 100 ohm.
B: Approx. 10 ~ 25 ohm.
Abnormal: Infinite or several
B
A
Normal: Approx.100~150 ohm
Abnormal: Infinite or several
Normal: Approximately
BK - RD: 5.1 Kohm
RD - WH: 2.1 Kohm
BK - WH: 2.1 Kohm
Abnormal: Infinite or several.
* Sensor cooking condition
1. Oven should be plugged in at
least 5 minutes before sensor
cooking.
2. Room temperature should not
exceed 95°F .
3. Be sure the exterior of the
cooking container and the
interior of the oven are dry.
Wipe each off with paper towel.
4. The oven will not generate
microwave energy for the first
28 seconds of the sensor
cooking cycle.
Cause
RESULTS
4 sec 18 sec
6 sec 16 sec
8 sec 14 sec
10 sec 12 sec
12 sec 10 sec
14 sec 8 sec
16 sec 6 sec
18 sec 4 sec
20 sec 2 sec
22 sec 0 sec
ohm.
ohm.