Sanyo EM-U1000W - Compact Microwave,10 Pwr Lvls,800 W,18"x14-3/8"x11-5/8",WE Service Manual page 19

pliers.
1 . 1 7 . 5 E X A M I N E T H E
1 . 1 7 . 5 E X A M I N E T H E
M I C R O W A V E O
M I C R O W A V E O
Pull out the power plug, take off the cabinet, discharge the
capacitor, measure the resistance value of the primary
winding and the secondary winding of the transformer with an
multimeter (FIG.5 – 10 and FIG.5 - 9). The resistance value of
the primary winding should be about 2.2 ohms, the secondary
winding should be about 130 ohms. Otherwise, it indicates the
transformer has broken, and should be replaced by a new
one.
If the transformer is normal, then the high voltage capacitor
should be checked. Pull out the connecting plug of the
capacitor, and measure it with R×1 grade of an multimeter,
the two rods of the multimeter connect the two polarity of the capacitor. When they just connected, the reading of
the multimeter should be zero, then increases to nine
megaohm slowly. Change the rod to different polarity, the
reading repeat from zero to nine megaohm (FIG.5 - 11), it
means the capacitor is normal. If the indicator of the
multimeter can't point out from zero to nine megaohms, it
indicates the high voltage capacitor has broken, and should
be replaced by a new one.
If it is normal between the two poles of the capacitor, then the
insulation between the capacitor pole and the cabinet should
be measured with R×10K grade of an multimeter. The
resistance value should be "∞" (FIG.5 - 12). If it is short
circuited or has a number reading, it indicates that the
capacitor has been punctured or electricity leaked, and should
be replaced by a same model, same capacity one.
Fig.5-10
If the resistance value of the capacitor's two poles are "∞", the capacitor is normal. Then check the earth of the
magnetron's two filaments to see whether they are short –
circuited (FIG.5 - 13). If they are short – circuited and the
filament strikes the shell of the magnetron, it indicates the
magnetron has broken, and should be replaced by a new,
same model one.
If the magnetron is also normal, then test the pilot switch.
Pull out the two plugs of the switch. Measure it with the R×1
grade of multimeter, the two rod connect the plug of the
switch, the resistance value should be "∞" (FIG.5 - 8).
Then press down the pilot switch with a screwdriver, if the
reading of the multimeter pointed to zero, it indicates the
pilot switch has broken, and should replace it with a new,
S T A R T I N G A N D T H E 8
S T A R T I N G A N D T H E 8
V E N
V E N
A F U S E O F T H E
A F U S E O F T H E
Fig.5-11
17
Fig.5-8
Fig.5-9
Fig.5-12
magnetron