Sharp R-209FW, Руководство по обслуживанию

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R-209(IN)
R-209(W)
R-209(Y)
11
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
Room temperature ....................... To = 21˚C Initial temperature .................... T1 = 11
°
C
Temperature after (52 + 3) = 55 sec. ..................................................................... T2 = 21
°
C
Temperature difference Cold-Warm (
∆
T = T2 - T1) ..............................................
∆
T = 10
°
C
Measured output power
The equation is “P = 80 x
∆
T” ...................................................... P = 80 x 10
°
C = 800 Watts
JUDGEMENT: The measured output power should be at least
±
15 % of the rated output power.
CAUTION: 1
°
C CORRESPONDS TO 80 WATTS. REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
Heat up for 55 sec.
B HIGH 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 high-voltage circuits, including the magnetron filament.
1. CARRY OUT 3D CHECKS.
2. 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 winding. The following readings should
be obtained:-
a. Primary winding .......................... 2.7 ohms approximately
b. Secondary winding .................... 205 ohms approximately
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.
3. Also, the high voltage transformer has the thermal cut-out in the primary coil. Measure the resistance
of the primary coil. The resistance of the primary coil should be above resistance unless the
temperature of the thermal cut-out in the primary coil reaches approximately 150˚C. The thermal cut-
out resets automatically at 130˚C. If an ohmmeter indicates an open circuit under normal condition,
replace the high voltage transformer because the primary coil (thermal cut-out) has opened. An open
primary coil (thermal cut-out) indicates overheating of the high voltage transformer. Check for
restricted air flow to the high voltage transformer, especially the ventilation opening.
4. CARRY OUT 4R CHECKS.
C 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 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.
NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF
THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BECAUSE
OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.
1000g
1000g
1000g
T1˚C
T2˚C