TROUBLESHOOTING
35
Replace the
filament
transformers.
Troubleshooting:
F3: MAG CURR (Magnetron Current Low)
Replace K6
relay.
U.S.
Intl.
Is the K6 mechanical
relay in good working
order?
Is the oven International or U.S.?
NO
YES
NO
NO
NO
YES
Reinstall all
parts and
place the
oven back in
service.
YES
Replace the
control board.
YES
Replace
affected
parts.
Replace the
capacitor(s).
Replace the
high-voltage
diode(s).
NO
Replace the
control board.
NO
YES
Inspect/replace wir-
ing between B-17,
C-14 of the control
board and terminals
A+B of the K8 relay.
Is voltage leaving the K8
anode relay on terminals
4+6?
Replace the K8 anode relay.
Are 10+ amps present
during the F3 fault
alarm?
Replace the
magnetron(s).
Inspect/replace wiring between terminal 4 (K8) and
T1-1 (HV transformer), and between terminal 6
(K8) and T2-3 (HV transformer; US 240 VAC) /
T2-2 (HV transformer; US 208 VAC or Intl.).
Energize the magnetron
circuit from Test Mode
(page 14) and test for
control voltage on the
K8 anode relay. Is 24
VDC present on
terminals A+B?
Confirm the F3 fuse is a
20-amp ATMR fuse. Is it
open/blown?
Replace the F3 fuse and
verify the operation of
the interlock switches
(page 21).
YES
Run test cook
cycles to see if
fault repeats
(page 9). If not,
clear faults. Did
fault repeat?
NO
YES
Energize the mag-
netron circuit from
Test Mode (page 14).
Are there 10+ amps
present on the cur-
rent transformer wire,
located on the control
board?
YES
Energize the mag-
netron circuit
from Test Mode
(page 14) and test
for control voltage
to the K8 anode
relay. Is 24 VDC
present on pins
B-17 and C-14 on
the control board?
NO
YES
Remove and inspect the
magnetrons for discolored
antennas or waveguide
contaminants. Were any
defects found?
NO
YES
NO
YES
YES
YES
NO
Test the high-voltage transform-
ers (page 24). Are they function-
ing properly?
NO
Test the filament transformers
(page 24). Are they functioning
properly?
NO
Test the capacitors (page 23).
Are they functioning properly?
NO
YES
Test the high-voltage
diodes (page 25). Are
they functioning
properly?
Is primary voltage present at the
high-voltage transformers (page
24)? NEVER TEST SECONDARY
VOLTAGES
Replace the
high-voltage
transformers.
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