30
THE MICROWAVE SYSTEM
IS
SUE
RE
SOLUTION
F3: Magnetron
Current Low
1. Check F3 Fuse.
o
Fuse OK: Go to Step 2.
o
Fuse Blown: Refer to “F3 Fuse Blown” on the following page.
2. Verify K1 Relay is operating correctly.
o
K1 Not Energizing: Correct Control issues. See Chapter 4 (The
Control System).
: Remove F3 Fuse before attempting to measure
filament currents.
o
K1 Energizing OK: Measure Filament Currents to each
Magnetron to verify Filament Transformers are OK. Place Amp
Probe on wires M1-F and then M2-F.
1. Current < 8 Amps on Magnetron 1, Magnetron 2 or both: Correct
wiring or replace failed Filament Transformer(s).
2. Current = 8 to 10 Amps on M1-F and M2-F. Filament
Transformers OK. Go to Step 3 below.
3. Verify K2 Relay is operating correctly.
o
K2 Not Energizing: Correct Control issues. See page 21, Figure 13.
o
K2 Energizing OK: Place the oven in Test Mode, place a Clamp-on
Amp Meter on the wire going to the Current Transformer on the
I/O Control Board. Measure and record current when Magnetrons
are energized.
1.
0 Amps – H
igh
V
oltage Transformers 1 and 2 not energizing.
Repeat Step 1 above. If both High Voltage Transformers have
failed
, replace High Voltage Transformers. See the Transformer
Winding Resistances Table on page 29 to verify failure.
2. Less than (<) 6 Amps – High Voltage Transformers are energizing,
but the Magnetrons are not drawing full current (14-17 Amps).
208 Volts is 17 Amps, 240 Volts is 14 Amps. Check High Voltage
D
iodes. I
f D
iodes fail, r
eplace D
iodes. I
f Diodes are OK, replace
Magnetron 1 and 2.
:
I
f M
agnetron failed, it is important to understand
why. Investigate each failed Magnetron. If the antenna is strongly
discolored, look for contamination in the Wave Guides. If
contami
nation exists, check the
W
av
e G
uide S
eals.
R
eplace any
broken Wave Guide Seals.
MICRO
WAVE SYSTEM TROUBLE SHOOTING
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