R1900J
6 – 5
[14] N: NOISE FILTER TEST
1. CARRY OUT
3D
CHECKS.
2. Disconnect the lead wires from the terminal the noise filter. Using an ohmmeter, check between
the terminals as described in the following table. If incorrect reading are obtained, replace the
noise filter.
3. CARRY OUT
4R
CHECKS.
[15] O: KEY UNIT TEST
1. CARRY OUT
3D
CHECKS.
2. Check Key unit ribbon connection before replacement.
3. If key unit ribbon connection is normal, carry out the following procedures.
4. Re-install the rear cover and the outer case (cabinet).
5. Reconnect the power supply cord.
6. The following symptoms indicate a defective key unit.
1) When touching the pads, a certain pad produces no signal at all.
2) When touching a number pad, two figures or more are displayed.
3) When touching the pads, sometimes a pad produces no signal.
7. When you can not judge if the key unit is normal or not by using the item 8 above, carry out following test procedures.
1) Disconnect the power supply cord, and then remove outer case and rear cover.
2) Open the door and block it open.
3) Discharge two high voltage capacitors.
4) Disconnect the leads to the primary of the power transformer.
5) Ensure that these leads remain isolated from other components and oven chassis by using
insulation tape.
6) Reconnect the power supply cord.
7) If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon
cable is making good contact, verify that the door sensing switch (stop switch) operates prop-
erly; that is the contacts are closed when the door is closed and open when the door is open.
If the door sensing switch (stop switch) is good, disconnect the flat ribbon cable that connects
the key unit to the control unit and make sure the door sensing switch is closed (either close
the door or short the door sensing switch connector). Use the Key unit matrix indicated on the
control panel schematic and place a jumper wire between the pins that correspond to the
STOP/CLEAR pad making momentary contact. If the control unit responds by clearing with a
beep the key unit is faulty and must be replaced. If the control unit does not respond, it is
faulty and must be replaced. If a specific pad does not respond, the above method may be
used (after clearing the control unit) to determine if the control unit or key pad is at fault.
8) For the door key unit, check the open/short and/or connection of the switch unit and the harness, too.
8. If the Key unit is defective.
1) Disconnect the power supply cord, and then remove outer case and rear cover.
2) Open the door and block it open.
3) Discharge two high voltage capacitors.
4) Replace the Key unit.
5) Reconnect all leads removed from components during testing.
6) Re-install the rear cover and the outer case (cabinet).
7) Reconnect the power supply cord after the rear cover and the outer case are installed.
8) Run the oven and check all functions.
MEASURING POINT
INDICATION OF OHMMETER
Between source terminals
Approx. 470K
Ω
Between source (Black) and load (Black) terminals
Short circuit.
Between source (White) and load (White/Brown) terminals
Short circuit.
WEAK
POINT
NOISE FILTER
NOISE SUPPRESSION COIL
LINE CROSS CAPACITOR
1.0μF / AC 275V
DISCHARGE RESISTOR
470K 1/2W
LINE BYPASS
CAPACITOR
0.0033μF / AC 250V
LINE BYPASS
CAPACITOR
0.0033μF / AC 250V
Load
(Black)
Load
(Gray/White)
Source
(Blue)
Source
(Brown)
5
4
3
2
7
8
9
6
1
2
3
4
1
5
6
7
2
3
4
1
5
6
7
2
3
4
1
5
6
7
8
STOP
CLEAR
1
START
3
4
9
5
6
0
7
8
STOP
CLEAR
1
2
X2/X3
START
3
4
9
5
6
0
7
8
CN-M
CN-R
CN-Z
2
CUSTOM
SETTING
SET
MEMORY
EXPRESS
DEFROST
MANUAL
REPEAT
POWER
LEVEL
CN-Q
< DOOR KEY UNIT >
< KEY UNIT >
< SW UNIT >
