B. Checkout Procedures. LG LRMM1430SW, LRMM1430SB

B. CHECKOUT PROCEDURES

(1) CHECKOUT PROCEDURES FOR FUSE BLOWING

CAUTION: REPLACE BLOWN FUSE WITH 20 AMPERE FUSE.

PROBLEMS CAUSES

Fuse blows immediately after the door is closed.

Fuse blows immediately after the door is opened.

Improper operation of the primary interlock, secondary interlock switches and/or the interlock monitor switch.

Fuse blows when the door is closed and START key is touched.

Malfunction of the Inverter, the magnetron, the fan motor or the circuit board.

NOTES:

- If the fuse is blown by an improper switch operation, replace the defective switches and the fuse at the same time.

After replacing the defective switches with new ones, make sure that they are correctly connected.

- Check for microwave energy leakage according to “1. ADJUSTMENT PROCEDURES” on page 3, when the primary interlock, secondary interlock switches and/or the interlock monitor switches are adjusted or replaced.

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(2) CHECKOUT PROCEDURES FOR RELAY

- PROBLEM (A) -

FAN motor and oven lamp turn on without touching

START key when the door is closed.

NO YES

GOOD

Remove the mate connector of I/O

CON from the circuit board does the unit still operate?

NO

Replace the circuit board

- PROBLEM (B) -

FAN motor and oven lamp turn on When the door is closed and START key is touched.

YES NO

GOOD Check the interlock switches

NO YES

Replace the micro switches.

Defective

RELAY or poor connection of relay

Replace

RELAY or correct the connection.

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(3) CHECKOUT PROCEDURES FOR CIRCUIT BOARD

The following symptoms indicate a defective circuit board.

(1) Check the input current. If the input current is more than 20A, check the magnetron and wiring. If the input current is less than 0.5 A, there is no input to the inverter.

(2) The start function fails to operate but the interlock switches, the door sensing and the relay check good.

(3) The unit with a normal relay continuously operates.

(4) The buzzer does not sound or continues to sound.

(5) Some segments of one or more digits do not light up, or they continue to light up, or segments light when they should not.

(6) Wrong figures appear.

(7) The figures of all digits flicker.

(8) Some of the indicators do no light up.

(9) The clock does not keep time properly.

NOTE: A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS

SERVICED FOR ANY REASON.

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