Sharp R-210A Test Procedures Procedure, Letter, Component Test, Bpower Transformer Test

R-210A

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

CAUTION: 1˚C CORRESPONDS TO 60 WATTS. REPEAT MEASUREMENT IF THE POWER IS INSUFFICIENT.

1 l 1 l 1 l 1 l

(T1C) (T2C)

(T1C) (T2C)

Heat up for 2 min. 22 sec.

BPOWER 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.

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	0.5 ohms approximately
b.Secondary winding	107 ohms approximately
c.Filament winding	less than 1 ohm

If the reading obtained are not stated as above, then the power transformer is probably faulty and should be replaced.

CARRY OUT 4R CHECKS.

CHIGH 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 kΩ in the other direction.

CARRY OUT 4R CHECKS. B

C

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 short-circuited capacitor shows continuity all the time.

E.An open capacitor constantly shows a resistance about 10 MΩ because of its internal 10MΩ resistance.

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