Sharp R-350J Service Manual page 13

PROCEDURE
LETTER
2. If the fuse F10A is blown when the door is opened, check the 1st. latch switch, 2nd. interlock relay and monitor switch.
If the fuse F10A is blown by incorrect door switching replace the defective switch(s) and the fuse F10A.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE FUSE F10A WITH THE CORRECT VALUE REPLACEMENT
I NOISE FILTER TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the noise filter.
Using an ohmmeter, check between the terminals as
described in the following table.
MEASURING POINT
Between N and L
Between terminal N and WHITE
Between terminal L and RED
If incorrect readings are obtained, replace the noise filter unit.
CARRY OUT 4R CHECKS.
J HIGH VOLTAGE FUSE TEST
CARRY OUT 3D CHECKS.
If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron. Check
them and replace the defective parts and high voltage fuse.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE THE HIGH VOLTAGE FUSE WITH THE CORRECT VALUE REPLACEMENT
K TOUCH CONTROL PANEL ASSEMBLY TEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike
conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and Key Unit, and
also the Control Unit is divided into two units, CPU Unit and Power Unit, and troubleshooting by unit replacement
is described according to the symptoms indicated.
1. Key Unit. Note: Check key unit ribbon connection before replacement.
The following symptoms indicate a defective key unit. Replace the key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
2. Control Unit.
The following symptoms indicate a defective control unit. Before replacing the control unit, perform the Key
unit test (Procedure L) to determine if control unit is faulty.
2-1 In connection with pads.
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.
2-2 In connection with indicators.
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
2-3 Other possible troubles caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
TEST PROCEDURES
COMPONENT TEST
INDICATION OF
OHMMETER
Open circuit
Short circuit
Short circuit
11
FUSE
F10A
R-350J