Sharp R-220EW Service Manual page 19

PROCEDURE
LETTER
MENU
GROUND MEAT
0.5lb
(5) If improper operation is indicated, the control unit is probably defective and should be checked.
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 563Ω ±
10%). If any abnormal condition is detected,
replace the control unit.
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.
TEST PROCEDURES
COMPONENT TEST
1ST STAGE
LEVEL TIME LEVEL
50% 1min.5sec.
OCCURRENCE
Only pattern at "a" is broken.
Pattern at "a" and "b" are broken.
OCCURRENCE
The rated AC voltage is not present between
Pin No. 3 of the 2-pin connector (A) and the
common terminal of the relay RY2.
The rated AC voltage is present at primary
side of low voltage transformer.
17
2ND STAGE 3RD STAGE
TIME LEVEL
30% 27sec. 10%
CAUSE OR CORRECTION
*Insert jumper wire J1 and solder.
*Insert the coil RCILF2003YAZZ between "c" and "d".
RY1
RY2
CAUSE OR CORRECTION
Check supply voltage and oven power cord.
Low voltage transformer or secondary circuit defective.
Check and replace.
TIME
55sec.
c
d
b
(J1)
a
R-220EW
R-230EK
R-230EW