R-9X55
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
An open circuit temperature fuse 150°C 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 170X (OVEN) indicates that the convection motor has over heated,
this may be due to convection motor locked.
An open circuit therma! cut-out 9O’C (FM) indicates that the fan motor winding has overheated, this
may be due to blocked ventilation or locked cooling fan.
H
MOTOR WINDING TEST
CARRY OUT DCHECKS
Disconnect the leads from the motor.
‘Using an ohmme,e + r, check the resistance between the two terminals as described !n the table beiow
Tabie: ;iesistance of Motor
1
I
~iotors
Resistance
! Fan motor
’ Apprcximately 173 !2
L-Jtirntable motor
Approximately 16 kl?
[ Convection fan motor 1 Approximately 190 Lh
1 3amper motor
1 Approxrmately 11 kL2
/
if !ncorrect readings are obrarned. replace the motor.
CARRY Ot’T 4F SbEZ$:S
L
CONVECTION HEATER TEST
CARRY OUT 30 CHECKS
Before carring out the following tests make sure the heater is fully cool.
1. Resistance of heater
Disconnect the wire leads to the heater to be tested. Using ohmmeter with low resistance range.
Check the resistance across the terminals of the heater.
The resistance of heater is approximately 37.5 ohms.
2. Insulation resistance
Disconnect the wire leads to the heater to be tested. Check the insulation resistance between the
element and cavity using a 500V - 1 OOMohms insulation tester. The insulation resistance should be
more than 1OMohms in the cold start.
If the results of above test 1 and/or 2 are out of above specifications, the heater is probably faulty and
should be replaced.
CARRY OUT 4R CHECKS
J
THERMISTOR TEST
CARRY OUT 3D CHECKS
Disconnect connector-E from the CPU unit. Measure the resistance of the thermistor with an ohmme-
ter. Connect the ohmmeter leads to Pin No’s E-3 and E-4 of the thermistor harness.
I
Room Temp.
1 Resistance
I
68F(2OC) - 86F(3OC) ;
Approx. 326kohms - 175kohms
/
If the meter does not indicate above resistance, replace the thermistor.
CARRY OUT 4R CHECKS
19
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