Sharp R-290H, Service Manual

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R-290H(S)
11
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
H FUSE T6.3A
CARRY OUT 3D CHECKS.
If the fuse T6.3A is blown when the door is opened, check the 1st latch switch, 2nd. interlock relay
control switch, monitor switch and 2nd. interlock relay RY2.
If the fuse T6.3A is blown by incorrect door switching, replace the defective switch(es) and the fuse T6.3A.
If the fuse T6.3A is blown, there is a shorts or grounds in electrical parts or wire harness.
Check them and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS.
CAUTION: Only replace fuse 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.
If incorrect readings are obtained, replace the noise filter unit.
CARRY OUT 4R CHECKS.
MEASURING POINT INDICATION OF OHMMETER
Between N and L Open circuit
Between terminal N and WHITE Short circuit
Between terminal L and RED Short circuit
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 the high voltage fuse.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE HIGH VOLTAGE FUSE WITH THE CORRECT VALUE REPLACE-
MENT.
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, 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. Replace the control unit.
2-1 Programming problems.
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 Display problems.
a) For a certain digit, all or some segments do not light up.
b) For a certain digit, brightness is low.
FUSE
T6.3A
N L
LINE CROSS CAPACITOR
0.068
µ
/AC250V
NOISE SUPPRESSION COIL
LINE BYPASS
CAPACITOR
0.0022
µ
/AC250V
LINE BYPASS
CAPACITOR
0.0022
µ
/AC250V
NOISE FILTER
WHT RED