Sharp R-403KK Service Manual page 19

PROCEDURE
LETTER
M FOIL PATTERN ON THE PRINTED WIRING BOARD TEST
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the
PWB, this foil pattern acts as a fuse.
1. Foil pattern check and repairs.
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Follow the troubleshooting guide given below for repair.
STEPS
1
2
5) Make a visual inspection of the varistor.
Check for burned damage and examine the
transformer with a tester for the presence of
layer short-circuit (check the primary coil
resistance which is approximately 563ý ±
10%). If any abnormal condition is detected,
replace the control unit assembly.
6) Reconnect all leads removed from
components during testing.
7) Re-install the outer case (cabinet).
8) Reconnect the power supply cord after the
outer case is installed.
9) Run the oven and check all functions.
2. Follow the troubleshooting guide given below, if indicator does not light up after above check and repairs
are finished.
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power transformer.
5) Ensure that these leads remain isolated from other components and oven chassis by using
insulation tape.
6) After that procedure, re-connect the power supply cord.
7) Follow the troubleshooting guide given below for repair.
STEPS
1
2
8) Disconnect the power supply cord, and then remove outer case.
9) Open the door and block it open.
10) Discharge high voltage capacitor.
11) Reconnect all leads removed from components during testing.
12) Re-install the outer case (cabinet).
13) Reconnect the power supply cord after the outer case is installed.
14) Run the oven and check all functions.
(5) The oven will operate for the first 16 seconds, without generating microwave energy.
TEST PROCEDURES
COMPONENT TEST
OCCURRENCE
Only pattern at "a" is broken.
Pattern at "a" and "b" are broken.
OCCURRENCE
The rated AC voltage is not present between
the normal open terminal of the relay RY1 and
the normal open terminal of the relay RY2.
The rated AC voltage is present at primary side Low voltage transformer or secondary circuit defective.
of low voltage transformer.
CAUSE OR CORRECTION
*Insert jumper wire J1 and solder.
*Insert the coil RCILF2003YAZZ between "c" and "d".
J1
c
L1
VRS1
CAUSE OR CORRECTION
Check supply voltage and oven power cord.
Check and replace control unit assembly.
17
a
b
d
R-405KS
R-403KK