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10
R-4G75(W)M
R-4G75(B)M
R-4G75(B)M
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
Initial temperature ......................................................................................................... T1 = 11
°
C
Temperature after (42 + 3) = 45 sec. ............................................................................ T2 = 21
°
C
Temperature difference Cold-Warm ............................................................................
∆
T1 = 10
°
C
Measured output power
The equation is “P = 100 x
The equation is “P = 100 x
∆
T” ........................................... P = 100 x 10
°
C = 1000 Watts Approx.
JUDGMENT: The measured output power should be at least
±
15 % of the rated output power.
CAUTION: 1
°
C CORRESPONDS TO 100 WATTS. REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
Heat up for 45sec.
1000g
1000g
1000g
T1˚C
T2˚C
B
POWER TRANSFORMER TEST
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.
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:-
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 ............ 1.3 ohms approximately
b. Secondary winding ....... 82 ohms approximately
c. Filament winding ........... less than 1 ohm
b. Secondary winding ....... 82 ohms approximately
c. Filament winding ........... less than 1 ohm
If the reading obtained are not stated above, then the power transformer is probably faulty and should be
replaced.
replaced.
CARRY OUT 4R CHECKS
C
HIGH VOLTAGE RECTIFIER ASSEMBLY TEST
HIGH VOLTAGE RECTIFIER 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 k
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 k
Ω
in the other direction.
CARRY OUT 4R CHECKS
ASYMMETRIC RECTIFIER TEST
CARRY OUT 3D CHECKS.
A
B
C
D2
D1
ASYMMETRIC
RECTIFIER
RECTIFIER
HIGH VOLTAGE RECTIFIER
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