Test Procedures - Electrolux MC2660E (EU) Service Manual

PROCEDURE
LETTER
B POWER TRANSFORMER TEST
SOI 05.06 FV

TEST PROCEDURES

NOTE: The operation time of the microwave oven is "t + 3" sec. 3 seconds are
needed for magnetron filament heat-up time.
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 turntable.
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.
Initial temperature ............................................................................. T1 = 11°C
Temperature after (47+ 3) = 50 sec................................................... T2 = 21°C
Temperature difference
Measured output power
The equation is "P = 90 x ∆T" .................................. P = 90 x 10°C = 900Watts
JUDGEMENT: The measured output power should be at least
the rated output power.
CAUTION: 1°C CORRESPONDS TO 90 WATTS. REPEAT
MEASUREMENT IF THE POWER IS INSUFFICIENT.
WARNING: High voltages and large currents are present at the
secondary winding and filament winding of the power
transformer. It is very dangerous to work near this part when
the oven is on. NEVER make any voltage measurements of
the high-voltage circuits, including the magnetron filament.
CARRY OUT 3D CHECKS
Disconnect the leads to the primary winding of the power 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 ............ 2 ohms approximately
b. Secondary winding ....... 160 ohms approximately
c. Filament winding ........... less than 1 ohm
If the reading obtained are not as stated above, then the power transformer is
probably faulty and should be replaced.
CARRY OUT 4R CHECKS
COMPONENT TEST
Cold-Warm...................................................T∆
Heat up for 50 sec.
17/34
= 10°C
±
15 % of
599 36 78-44