Panasonic NE-992 Service Manual page 29

CHECK RESULT CAUSE REMEDY
2. 240V AC is applied to primary side of high voltage transformer.
No continuity Defective magnetron Replace
Disconnect one lead wire con-
nected to filament terminal of
magnetron and check the con-
tinuity of magnetron's filament
Check the 0.5A fuse
between H.V.Capacitor 0.5A fuse open
and magnetron
als of magnetron and check
the continuity between filament
and magnetron case
b e a s Replace diode assy with 0.5A
Check the 0.5A fuse with diode 0.5A fuse open fuse NOTE:
Check the continuity of the eke .
' a nae Open winding of the high vol-
high vottage transformer prim No continuity tage transformer Replace
ary winding (0—240
Check the insulation of filament Detective high voltage trans-
winding of high voltage trans- Poor insulation Replace
former former
Check the continuity of fila-
ment winding of H.V.Trans- No continuity Defective H.V.Transformer Replace
former
Normal Aging change of magnetron Replace magnetron
NOTE: 0.5A fuse will be open when diode is shorted in order to prevent from overheating of H.V. Transformer. Therefore, in this case, diode may be
possibly shortcircuited.
{TROUBLE 4] Microwave output power is low. First of all, check if output is really low by following "Measurement of
microwave output" on page 25.
CHECK RESULT CAUSE REMEDY
Lower than 220 volts (in the 240
volts area)
Decrease in power source vol-
tage
inform customer of required
tage with magnetron oscil-
lating.
Defective digital programmer
circuit
Check the timing periods of
the 18V DC being applied to
the power relay 5 coil (Refer to
page 10 for the timing periods
of the power relay 5)
Abnormal Replace
Replace depending on the re-
Aging change of magnetron