Procedure N : Foil Pattern On The Printed Wiring Board Test - Sharp R-305KS Service Manual

R305KS

[15] Procedure N : 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 OCCURRENCE
1 Only pattern at "a" is broken.
2 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".
5) Make a visual inspection of the varistor. Check for burned damage and examine the trans-
former with a tester for the presence of layer short-circuit (check the primary coil resis-
tance which is approximately 563Ω±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
The rated AC voltage is not present between the normal open terminal of
1
the relay RY1 and the normal open terminal of the relay RY2.
The rated AC voltage is present at primary side of low voltage trans-
2
former.
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.
CAUSE OR CORRECTION
*Insert jumper wire J1 and solder.
OCCURRENCE
8 – 7
d
a
c
CAUSE OR CORRECTION
Check supply voltage and oven power cord.
Low voltage transformer or secondary circuit defective.
Check and replace control unit.
b