Pratica Chef Express Service Manual page 68

MICROWAVE SYSTEM
62
High Voltage Diode
The high voltage diode is a device that acts as a bridge by connecting several semi-conductor diodes
in a series to increase the reverse voltage capability and enables the current to flow in one direction,
but not the other. The diode transforms the alternating current into continuous and prevents the
filament voltage from becoming positive. The diode utilized in the Chef Express oven is of
16KV/750mA.
Testing HV Diode
WARNING: Never attempt to measure high voltage directly. Death or serious injury could
result. Always make sure to discharge the capacitor manually before commencing repair.
To perform the diode test, a multimeter and an extra 9V battery will be necessary.
1) Remove the rear panel of the unit.
2) Unplug the oven and discharge the capacitor manually by grounding each capacitor terminal.
3) Disconnect the cables from the diode and manually discharge the capacitors.
4) Connect the voltage meter in series with high voltage diode.
5) Using a multimeter set to DC voltage, connect one meter lead to one side of a 9-volt battery
and the other lead to one side of the high voltage diode.
6) Connect the other side of the 9-volt battery to the other side of the high voltage diode. DC
voltage should be present on the meter in only one direction.
7) Depending on the voltage of the battery, voltage between 5-7 VDC should be present in only
one direction and 0-0.1 VDC in the other direction.
• If voltage is present or is not present in both directions, replace the diode.