Sharp R-4H55 Service Manual page 16

TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
NOISE FILTER TEST (New Zealand Model)
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the noise filter.
Using an ohmmeter, Check between the terminals as de-
scribed in the following table.
L (min) 1 CxtiO% 1 CyX?O%
l.OmH 1 O.lpF 1 22OOpF
MESURING POINT INDICATION OF OHMMETER
Between N and L Open circuit
Between terminal N and WHITE Short circuit
Between terminal Land RED
Short circuit
If incorrect readings are obtained, replace the noise filter unit.
CARRY OUT 4R CHECKS.
G MONITOR RESISTOR TEST
CARRY OUT =CHECKS.
Disconnect the leads from the monitor resist. Using an ohmmeter and set on a low range. Check
between the terminals of the monitor resistor.
The resistance of monitor resistor is aoorox. 0.8 ohms.
If incorrect readings are obtained, replace the monitor resistor.
CARRY OUT 4R CHECKS.
H TEMPERATURE FUSE OR THERMAL CUT-OUT TEST
CARRY OUT 3D CHECKS
Disconnect the leads from the terminals of the temperature fuse or thermal cut-out. Then using an
ohmmeter, make a continuity test across the two terminals as described in the table below.
CARRY OUTa CHECKS
Table: Thermal cut-out Test
Parts Name
Thermal cut-out 145'C
Temperature fuse 15o'C
Temperature of "ON" condition
Temperature of "OFF" condition
Indication of ohmmeter
(closed circuit)
(open circuit)
(When room temperature
is approx. 20-C)
-20-c
Above 145-C
Closed circuit.
This is not resetable type
Above 150X
Closed circuit.
If incorrect readings are obtained, replace the temperature fuse or thermal cut-out.
An open circuit temperature fuse 150% (MG) indicates that the magnetron has overheated, this may
be due to resistricted ventilation, cooling fan failure or a fault condition within the magnetron or HV
circuit.
An open circuit thermal cut-out 145°C (OVEN) indicates that the foods in the oven may catch fire, this
may be due to over heating produced by improper setting of the cooking time or failure of the control
panel.
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