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Troubleshooting of Inverter Circuit (U) and Magnetron
NEW H.V.
This oven is programmed with a self diagnostics failure code system which will help for troubleshooting. H97, H98, and H99 are the provided failure
codes to indicate magnetron and inverter circuit problem areas. This section explains failure codes of H97, H98, and H99. First, you must program
the DPC by pressing Clock , Time , Start , Power Level . Program unit for operation. H97, H98, H99 appears in display window a short time after start
key is pressed and there is no microwave oscillation.
NOTE: DO NOT try to repair this Inverter
Power Supply (U) and also DO NOT
RE-ADJUST PRESET VOLUME on
the board. It is very dangerous to
repair or adjust without sufficient test
equipment because this circuit han-
dles very high voltage and very large
current. Off alignment of inverter
board operation is dangerous.
Operating a misaligned Inverter cir-
cuit is dangerous due to the very high
voltage and current that is produced
by this board. Defective boards must
be replaced with a new one.
* Check magnetron filament for open or short
to casing before proceeding to determine a
good magnetron.
Check inverter control signal at
CN701, pin 1 and 2
H97, H98, or H99 appears in display
window
Check magnetron filament continuity
Check Inverter input AC voltages at
CN702
H.V. Inverter (U)
(SEE NOTE)
Magnetron*
DPC board
Loose relay wiring
DPC board
unplug CN701 and measure at
lead wire harness side
refer to componenet test
procedures
unplug CN702 and measure
at lead wire harness side
AC3V
OK
AC 120V
Open
OV
OV
NOTE: After check, unplug unit to reset to normal operation mode.
Alternate way to troubleshoot oven with AC Ampere meter used
H97, H98, H99 appears in display window a short time after start key is pressed and no microwave oscillation with AC Ampere
meter used for troubleshooting
Check magnetron filament
continuity
H97, H98, or H99 appears in display
window
Check oven input AC amperes
measure at oven plug
STOP!
If all the above are
OK up to this point,
there may be a H.
V. Inverter problem
(SEE NOTE)
DPC board
Loose wiring
Magnetron*
refer to component test
procedures
more than 1A
OK
0.4-0.8A
Open
NOTE: If filament is opened,
AC input Amperes 1 to 1.7A
will flow
NOTE: After check, unplug unit to reset to normal operation mode.
NOTE: DO NOT try to repair this Inverter
Power Supply (U) and also DO NOT
RE-ADJUST PRESET VOLUME on
the board. It is very dangerous to
repair or adjust without sufficient test
equipment because this circuit han-
dles very high voltage and very large
current. Off alignment of inverter
board operation is dangerous.
Operating a misaligned Inverter cir-
cuit is dangerous due to the very high
voltage and current that is produced
by this board. Defective boards must
be replaced with a new one.
* Check magnetron filament for open or short
to casing before proceeding to determine a
good magnetron.
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