MOP01010029T8
All INVERTER MODELS
Subject: This technical information describes the repair procedure for the following inverter circuit boards. *606Y4N10GP *606Y4L10GP *606Y4V00GP *606Y4V20GP *606Y4V00BP *606Y4J00**
© 2002 Matsushita Electric Industrial Co., Ltd. All rights reserved. Unauthorised copying and distribution is a violation of law.
Always unplug the Microwave Oven from the electricity supply, before removing the outer panel.
Never touch the inverter PCB with the microwave oven plugged into the electricity supply. The inverter circuit board handles voltages up to 5000 volts and is very dangerous
Do not touch the heat sink during operation of the microwave oven. The heat sink handles high voltage and becomes very hot.
Always discharge the high voltage capacitors located on the inverter circuit board before beginning any troubleshooting.
Only test the inverter circuit board by installing it completely into the oven and refitting the outer panel.
Always connect the inverter circuit to earth via the earth plate. It is very dangerous to operate the inverter circuit when it is not connected to earth.
Pbf: Lead free solder has a higher melting point than standard solder; typically the melting point is 30° - 40° C higher. Use a high temperature soldering iron with temperature control, set it to 370° 10± C.Lead free solder splashes when heated too high (about 600° C)
Unplug the oven from the mains supply and leave it for more than 30 seconds before removing the outer panel
Use an insulated lead wire to short between the anode of Diode D701, and the cathode of diode D702.(See figure 1 for inverter circuit *606Y4L10GP *606Y4N10GP *E606Y4J00**) or (See figure 2 for inverter *606Y4V00GP *606Y4V20GP *606Y4V00BP)
Discharging the Capacitors on the inverter circuit *606Y4L10GP *606Y4N10GP *606Y4J00**
Discharging the capacitors on the inverter circuit *606Y4V00GP *606Y4V20GP *606Y4V00BP
Check the inverter circuit board for cracks, broken components, burnt components and for damaged copper tracks.
Remove the inverter PCB from the oven before attempting to test any components. Do not try to test any components with the inverter PCB installed in the microwave oven.
Remove the solder holding each leg of the high power transistors to the inverter circuit board.
Test the high power transistors for resistance between the Emitter - Collector, Emitter - Gate, Gate - Collector junctions. Refer to (figure 3) for the expected readings of a functional Power transistor.
check the resistance across each junction of the power transistors.
Remove the solder holding each leg of the diode-bridge to the inverter circuit board.
Check the resistance across each diode in the diode-bridge in both forward and reverse bias. See figure 4 for the expected reading of a functional diode-bridge.
Checking the resistance across the bridge-diode
Inspect the high voltage capacitors for any visible damage.
Remove the capacitor from the inverter circuit board and measure the resistance across the terminals, a defective capacitor will indicate low resistance. (Short circuit). (Note: On the inverter PCB’s *606Y4V00GP *606Y4V20GP *606Y4V00BP,the high-voltage capacitors are in parallel with the high-voltage diodes. If these diodes are short circuit, the capacitors will falsely read short circuit, if they are measured whilst still soldered into the board.).
Remove the high voltage diodes from the inverter circuit board and check the resistance using a meter with a voltage of more than 9 Volts.
Refer to the table (Figure 5) for the expected resistance readings of a functional diode.
If the power transistor’s IGBT’s are defective, replace the 2 power transistors (Q701 and Q702) together with the capacitor C806. The repair kit A691E4V10GP consists of these 3 components. Figure 6 shows the position of each ofthese components.
Components to replace if IGBT’s are defective
Remove all of the solder from each leg of the capacitor (C806). Remove the capacitor from the board.
Place the capacitor in position and carefully solderer each leg. Check that no solder bridges the copper tracks of the circuit board.
Remove all of the solder from each leg of the power transistors (Q701,Q702) and the diode bridge(DB701). Use a high-power soldering iron to ensure that the legs of each component are free from the inverter circuit board.
Remove the heat sink with the components attached away from the inverter circuit board.(Figure 7)
Remove the defective component by removing the screw securing the component to the heat sink.
Clean the surface of the heat sink to remove all dust and debris.(Figure 8)
Apply heat sink compound to the surface of the heat sink.(Figure 8)
Place the new component in position and replace the screw to secure the component to the heat sink.
Place the heat sink and components back in position on the inverter circuit board. Insert the legs of each component legs completely into the board. Solder each leg into the circuit board, add sufficient solder to withstand the high current.( Figure 9). Check for dry solder joints and solder bridges between tracks.
Removal of the power transistors and the diode bridge on the inverter PCB *606Y4V00GP *606Y4V20GP *606Y4V00BP
Clean all debris from the heat sink surface
Add sufficient solder so the joint can withstand high current.
Remove all of the solder from each leg of the power transistors (Q701,Q702) and the diode-bridge(DB701). Use a high-power soldering iron to ensure that the legs of each component are free from the inverter circuit board.
Remove the 2 screws holding the heat sink to the circuit board as follows: (Figure 10)
Place a small amount of solder onto the tip of the high powered soldering iron.(Figure 10)
Position the tip of the screwdriver into the head of the screw, Use the high powered soldering iron to melt the solder around the screw head; when the solder has melted turn the screw in an anti clockwise direction. Hold the soldering ironagainst the head of the screw until you have removed the screw from the board. (Figure 10)
Remove the heat sink and components from the circuit board.
Remove the defective component from the inverter circuit board by removing the screw securing the component to the heat sink.
Place the components back in position on the inverter circuit board, insert the component legs of each component completely into the board. Replace the 2 screws to secure the heat sink. Reapply solder to the head of both screws and solder thelegs of each component into the circuit board. Add sufficient solder to withstand high current. (Figure 9)
Removing the heat sink and IGBT’s
Before placing the repaired inverter circuit board into the microwave oven check for any dry joints or bridged solder. Install the inverter circuit board into the microwave oven to test, do not attempt to test the inverter circuit board using extensioncables. When fitting the inverter circuit board into the microwave oven make sure you connect the inverter to earth via the earthing bracket. It is extremely dangerous to operate the inverter circuit with no earth connection.
Install the inverter circuit board in the microwave oven. Plug in the connections CN701,CN702 and CN703. Check that the inverter is connected to earth via the earthing bracket.
Connect the oven to a suitable ampere meter to measure the input current during normal microwave operation. (See tools and jigs on Page for a suitable meter)
Operate the microwave oven on high power for one minute.
Check the input current. (Refer to the individual service manual for the specified input current for your specific model).
Do not attempt to adjust the variable resistor VR701. Adjustment is only necessary when the high voltage transformer has been replaced. However, if the high voltage transformer is defective replace the inverter circuit as a complete unit.
If the high volatge transformer on the inverter circuit emits a loud noise, refer to the repair procedure below.
When the power transistors short circuit the power transistor gate resistors may blow. This fault is quite rare, however, if the high voltage transformer emits a loud noise after you have replaced the power transistors (Q701)(Q702) and capacitor(C806), replace the resistors: R713 and R714. See figure 11.
Replace R713 and R714 if high voltage transformer is noisy (*606YV00GP) (*606Y4V20GP) (*606Y4V00BP)
When ordering replacement parts, please order using the part numbers exactly as shown in the parts list.
Components identified by mark have special characteristics important for safety. When replacing any of these components, use only the manufacturers specified part.
All part numbers are supplied from Microwave Oven Division in Japan
All of the following test jigs can be ordered form MOD Japan.
Power Check Meter. This meter can be used to measure the microwave oven input current and line voltage.
The following plug and outlet arrangements are available
Universal Outlet This is designed to fit all types of plugs including the earth and grounding plugs.
Fluorescent light bulb (4W) Part number A600Z-FL4W
This can be used to check microwave oscillation.
Caution
Always place 1 liter of water inside the cavity with this bulb. Do not expose the bulb to microwave energy for longer than 10 seconds. Leaving the bulb in the cavity with microwave oscillation for a long period will cause the bulb to overheat andburn.
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