Re-Setting Of Microcomputer At Power Failure; Diagnosis Method Of Failure Around Pwb - Sharp SJ-GC440V-BK Service Manual

3. RE-SETTING OF MICROCOMPUTER AT POWER FAILURE

• At the power failure for over 0.2 second, the control of the microcomputer will be reset.
(Microcomputer might continue to operate for approximately 10 seconds maximum at power failure depending on the
load at the operation. When you need the difinite power off condition ,approximately 30 seconds is necessary.)
• When the power is re-supplied, the normal cooling will be resumed.

4. DIAGNOSIS METHOD OF FAILURE AROUND PWB

In case of any abnormality of refrigerator, check by the following procedure;
1. Disconnect power supply and check the following point.
• Is there any failure portion in inserting connectors?
2. Detach the PWB and check the appearance.
• Is there any burning or abnormal damage?
3. Check the conditions of the fuse and the varistor. (Fuse and varistor are located at the position in the figure.)
• Under the condition of power supply plug connected;
In case of cooling but indoor lamp lighting, there might be a possibility of fuse (F301) melt down.
(However, these indications do not conclude the cause of the defect.)
When the fuse F302 is melt down, indoor lamp, door switch and defrosting heater are not electrified.
When the fuse F303 is melt down, PWB does not operate at all.
Melting in the fuse cannot be checked visually (as the safer one than transparent glass tube is used).
• Be sure to detach the connector "CN301" when you measure the resistance between the both ends of the fuse by
the tester.
• Next, check the appearance of varistors.
Varistor 303
Varistor 305
Varistor 304
4. Check whether the temperature (resistance value) shown by R-thermistor is correct or not. (Refer to the table
below.)
• Detach the connector "CN309" on the PWB and measure the resistance value between 1 and 2 pins.
5. Check whether the temperature (resistance value) shown by Def-thermistor is correct or not. (Refer to the table
below.)
• Detach the connector "CN310" on the PWB and measure the resistance value between 6 and 7 pins.
6. Check whether the temperature (resistance value) shown by F-thermistor is correct or not. (Refer to the table
below.)
• Detach the connector "CN310" on the PWB and measure the resistance value between 4 and 5 pins.
Fuse 303
Fuse 301
Fuse 302
17
SJGC480VL