R-64ST - 14
Heat up for 55sec
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 measure-
ments of the high-voltage circuits, including the magnetron filament.
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:-
a. Primary winding
approximately 2.22 ohms
b. Secondary winding
approximately 142 ohms
c. Filament winding
less than 1 ohm
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.
Initial temperature .................................................................................................. T1 = 11
°
C
Temperature after (52 + 3) = 55 sec ...................................................................... T2 = 21
°
C
Temperature difference Cold-Warm .......................................................................
∆
T1 = 10C
Measured output power
The equation is “P = 80 x
∆
T” ..................................................... P = 80 x 10
°
C = 800 Watts
JUDGMENT: The measured output power should be at least
±
15 % of the rated output power.
CAUTION: 1
°
C CORRESPONDS TO 75 WATTS. REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
1000g
1000g
1000g
T1˚C
T2˚C
Measuring method:
1. Measure the initial temperature of the water before the water is added to the vessel.
(Example: The initial temperature T1 = 11
°
C)
2. Add the 1 litre water to the vessel.
3. Place the load on the centre of the shelf.
4. Operate the microwave oven at HIGH for the temperature of the water rises by a value
∆
T of
(10
±
2) K.
5. Stir the water to equalize temperature throughout the vessel.
6. Measure the final water temperature. (Example: The final temperature T2 = 21
°
C)
7. Calculate the microwave power output P in watts from above formula.
B
HIGH VOLTAGE TRANSFORMER TEST
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
R64ST_S.MANUAL
12/8/01, 11:01 am
14
