| TEST PROCEDURES |
PROCEDURE |
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LETTER | COMPONENT TEST |
BHIGH VOLTAGE TRANSFORMER TEST
WARNING: High voltage and large currents are present at the secondary winding and filament winding of the high voltage transformer. It is very dangerous to work near this part when the oven is on. NEVER make any voltage measurements of the
CARRY OUT 3D CHECKS.
Disconnect the leads to the primary winding of the high voltage transformer. Disconnect the filament and secondary winding connections from the rest of the HV circuitry. Using an ohmmeter, set on a low range, it is possible to check the continuity of all three windings. The following readings should be obtained:
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a. Primary winding | approximately 1.8 Ω | approximately 1.2 Ω |
b. Secondary winding | approximately 75 Ω | approximately 75 Ω |
c. Filament winding | less than 1 Ω | |
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If the readings obtained are not stated as above, then the high voltage transformer is probably faulty and should be replaced.
CARRY OUT 4R CHECKS.
CHIGH VOLTAGE RECTIFIER ASSEMBLY TEST CARRY OUT 3D CHECKS.
Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal B+C of the high voltage rectifier and note the reading obtained. Reverse the meter leads and note this second reading. The normal resistance is infinite in one direction and more than 100 kΩ in the other direction.
CARRY OUT 4R CHECKS. | B |
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| HIGH VOLTAGE RECTIFIER | ||||
NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BE- CAUSE OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIREC- TIONS.
DHIGH VOLTAGE CAPACITOR TEST CARRY OUT 3D CHECKS.
A.Isolate the high voltage capacitor from the circuit.
B.Continuity check must be carried out with measuring instrument which is set to the highest resistance range.
C.A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10MΩ after it has been charged.
D.A
E.An open capacitor constantly shows a resistance about 10 MΩ because of its internal 10MΩ resistance.
F.When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
G.The resistance across all the terminals and the chassis must be infinite when the capacitor is normal.
If incorrect reading are obtained, the high voltage capacitor must be replaced.
CARRY OUT 4R CHECKS.
ESWITCH TEST
CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following table.
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