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When the high-voltage winding starts to go toward
negative, the high-voltage diode becomes non-
conducting with the charged high-voltage capacitor
in series with the high-voltage winding. When the
transformer gets to its negative peak of -2400 VPK,
the voltage applied to the filament is negative 4500
volts. The high-voltage diodes are rated at 16
kVDC.
Testing a High-Voltage Diode
DANGER: Never attempt to measure high
voltage directly. Death or serious injury
could result.
1. Disconnect the oven from the power source.
2. Fully discharge the capacitors.
3. Connect the voltage meter in series with diode.
4. 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 diode.
5. Connect the other side of the 9-volt battery to
the other side of the diode. DC voltage should
only be present on the meter in one direction.
6. Switch the meter leads on the diode, which will
cause the opposite reading to be visible.
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.
High Voltage Transformers Primary Voltage, Frequency, Taps,
and Resistance
Secondary Taps and Resistance
NGC-3062-1 208 VAC, 60 Hz, 1 & 2,
0.819–1.001
WW
240 VAC, 60 Hz, 1 & 3,
0.972–1.188
WW
4, Ground, 53.60–65.52
WW
NGC-3062-2 230 VAC, 50 Hz, 1 & 2,
0.972–1.188
WW
3, Ground, 57.52–70.30
WW
NGC-3062-3 200 VAC, 50/60 Hz, 1 & 2,
0.784–0.958
WW
3, Ground, 55.75–68.13
WW
Filament Transformers Primary Voltage, Frequency, Taps,
and Resistance
Secondary Taps and Resistance
NGC-3061-1 208 VAC, 60 Hz, 1 & 2,
17.49–21.37
WW
240 VAC, 60 Hz, 1 & 3,
20.61–25.19
WW
4, 5, very low resistance - if read-
ing is open, transformer has failed.
NGC-3061-2 230 VAC, 50 Hz, 1 & 2,
18.99–23.21
WW
3, 4, very low resistance - if read-
ing is open, transformer has failed.
NGC-3061-3 200 VAC, 50/60 Hz, 1 & 2,
15.70–19.18
WW
3, 4, very low resistance - if read-
ing is open, transformer has failed.
High Voltage and Filament Transformer Resistance Table