Sanyo EM-C950 User manual

SERVICE MANUAL Microwave Oven EM-C950 (~’ 0,
Foreword
Read this manual carefully, especially precaution on microwave energy, and follow the procedure strictly. Careless servicing and
testing may expose yourself to the microwave energy leakage.
PRECAUTIONS
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EX-
CESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open.
(b) Make the followlng safetv checks on all ovens to be serviced before activating the magnetron or other microwave source,
and make repairs as necessary:
(1) Interlock operation, (2) proper door closlnq, (31 seal and sealing surfaces (arcing, wear, and other damage), (4)
damage to or loosening of hinges and latches, (5) evidence of dropping or abuse.
(c) Before turning O(I microwave power for any service test or InspectIon wlthtn the microwave generating compartments,
check the magnetron, wave gu!de or transmission line, and cavity for proper alignment, integrity, and connections.
(d) Any defective or misadjusted components In the Interlock, monitor, door seal, and microwave generation and trans.
mission systems shall be repaired, replaced, or adjusted by procedures described In th!s manual before the oven IS released
to the owner
REFERENCE NO.

-TABLE OF CONTENTS –
Adjustment Procedures ..:.... ...............1 Test Procedures and Troubleshooting . . . . 4-10
Specifications ............................2 Disassembly Instructions .II-13
Power Output Measurement . . . . . . . . . . . . . . . . . . . 2Exploded View and Parts List . . 14-20
Precautions and Repair Service Tips . . . . . . . . . 2Overall Circuit Diagram .................. 21
Circuit Diagram ............................3
CAUTION
MICROWAVE RADIATION
PERSONNEL SHOULD NOT BE EXPOSED TO THE
MICROWAVE ENERGY WHICH MAY RADIATE
FROM THE MAGNETRON OR OTHER MICRO-
WAVE GENERATING DEVICE IF IT IS impro-
perly USED OR CONNECTED. ALL INPUT AND
OUTPUT MICROWAVE CONNECTIONS, WAVE-
GUIDES, FLANGES, AND GASKETS MUST BE
SECURE. NEVER OPERATE THE DEVICE WITH-
OUT AMICROWAVE ENERGY ABSORBING
LOAD ATTACHED. NEVER LOOK INTO AN
OPEN WAVEGUIDE OR ANTENNA WHILE THE
DEVICE IS ENERGIZED.
1. ADJUSTMENT PROCEDURES
TO AVOID POSSIBLE EXPOSURE TO MICROWAVE
ENERGY LEAKAGE, THE FOLLOWING ADJUST-
MENT OF THE INTERLOCK SWITCHES SHOULD BE
MADE ONLY BY AUTHORIZED SERVICE PERSON-
NEL.
PRIMARY INTERLOCK SWITCH, SECONDARY
INTERLOCK SWITCH, INTERLOCK MONITOR
SWITCH AND DOOR SENSING SWITCH
ADJUSTMENT
(Figure 1)
(1) Loosen 2screws securing the lever stopper.
(2] Adjust the lever stopper position so that it IS pushed
forward and pull backward until thele IS about zero
gap
2,1 Beween the latch lever and the switch
bodies on the secondary interlock switch
and the door sensing swich.
2.2 Beween the latch lever and the switch
body on the interlock monitor switch
2.3 Beween the latch lever and the switch
body on the primary interlock switch
when the door latch is securelv locked.
(31
(4)
(5)
Tighten the lever stopper screws securely.
Make sure the interlock monitor switch closes after
the primary interlock switch opens when the door
IS opened very slowly, according to “CHECKOUT
PROCEDURE FOR SWITCHES” on page 6,
Make sure the interlock monitor switch opens
before the primary interlock switch closes when the
door is closed very slowly, according to “CHECK-
OUT PROCEDURE F,OR SWITCHES” on page 6.
(6) Make sure the microwave energy leakage is below
the limit of the regulations (5mW/cm2 )when
measured with adetector.
(All service adjustments must be made for minimum
micro wave energy leakage readings. )
Lever stopper Door latch
&?
Latch lever
.--— —
—--- –-l -J IPrimary interlock
-——— fib
1
Interlock monitor
switch
11
k
=--
2i!l!7-ziil
I.
—sensing
Switch
Screws
Figure 1
–l–

2. SPECIFICATIONS
Rated Power Consumption...l 400W
Rated power Supply ..,,,..,,,.. 220- 230 V/50Hz
Microwave output ................ 900/450/150/80W
/Defrost
Frequency ............................ 2,450 MHz+50MHz
Saftey Device ...................... Thermal Protector for
Cavity, open at 135*C
Themal Protector for
Magnetron, open at 135°C
Fuse (Carloridge Type 8A)
Primary interlock switch
Secondary interlock switch
Interlock monitor switch
Relay RL-2 on Control
circuit board
Timer ...................at................6 OMin. at 900/450/150 W
90Min. at 80 Won Defrost
Overall dimensions ............... 520wx413d x350 hmm
Oven cavity size .................... 330wx348dx 173 h mm
Effective Capacity of Oven .....2O liter
Net Weight ............23K!l............23K!l
3. POWER OUTPUT MEASUREMENT
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Prepare 1000*5g tap water.
Adjust water temperature to 10°t20C.
Pour water into acontainer made of borosilicate
glass, 190mm outer diameter cylinder, maximum
3mm thickness.
Note. Use the container kept on the room temper-
ature.
Place the container in the center of oven cavity.
Set the heating time for 47 seconds and rating full
power and then ftart oven.
Take the container out immediately when heating
time is up,
Stir water for making even water temperature in the
container.
Measure water temperature.
Water temperature rise shall be 8° to 12°C.
4. PRECAUTIONS AND REPAIR SERVICE TIPS
PRELIMINARY
A. SINCE NEALY 4,000 VOLTS EXIST IN SOME
CIRCUITS OF THE MICROWAVEOVENS,
REPAIRS SHOULD BE CARRIED OUT WITH
GREAT CARE.
B.TO AVOID POSSIBLE EXPOSURE TO MICRO-
WAVE ENERGY LEAKAGE, THE FOLLOWING
PRECAUTIONS MUST BE TAKEN BEFORE
SERVICING.
(1) Before the power is applied:
(a) Open and close the door several times to make
sure the primary interlock switch, the secondary
interlock switch, the interlock monitor switch
and the door sensing switch operate properly.
listen for the cliking sound from the switches.
Make sure the interlock monitor switch is
closed after the primary interlock switch is
opened when the door is opened.
(See pages 1 and 6)
(b) Make sure the perforated screen and the choke di-
electric of the door are correctly mounted.
(2) After the power is applied:
(a) Open and close the door to see If the interlock
mechanism operates properly.
(b) Check microwave energy leakage with aleakage
detector and confirm the energy leakage is below 5
mW/cm2 ).
(3) Do not operate the unit until it is completely repair-
ed, if any of the following conditions exists.
(a) Door does not close firmly against the cavity front.
(b) The hinge is broken.
(c) The choke dielectric or the door seal is damaged.
(d) The door is bent or warped, or there is any other
visible damage to the oven that may cause micro-
wave energy leakage.
(e) Make sure that there are no defective parts in the
interlock mechanism.
(f) Make sure there are no defective parts in the micro-
wave generating and transmission assembly. (espe-
cially waveguide).
(4) Following items should be checked after the unit is
repaired.
(a) The interlock monitor switch is connected correctly
and firmly.
(b) The magnetron gasket on the magnetron IS properly
positioned.
(c) Waveguide and oven cavity are intact (no leakage of
microwave energy).
(d) The door can be Properly closed and the safety
switches work Properly.
(e) The oven must be stopped when the door is opened
or the time is up
The oven must not be operated with any of the above
components removed or bypassed.
HINT FOR LAMP CHANGE
Before removing the cabinet, pull out the main plug.
If you want to check the new lamp with the oen
cabinet, take care of the following safety cautions.:
Do not touch live parts, The lamp holder is not connected
to the earth wotecton lead bv ametric screw.
–2–

5. CIRCUIT DIAGRAM
t
LN
P’ 1’
L
r——.
650JJH
8A(T~ 1
~650p HM“ /
2200 PF(Y)
1
X2
o. 06 EI)JF J
——
m
0
-Jt-
<0
Xu
al-
Wo
SW
l-nm
0
‘<z>
J-m
x
CJ
0
-II
Xucl
uul-
t-+-
az~
A- U-I
-11-
av
Xw CAVITY
ml- LIGHT
Wo
sSW
+b-- /0
HIGH VOLTAGE
TRANSFORMER
i\l
L_
‘] MDIODE
—
Mq
.— 1
MAGNETRON
+11 1
c
u-l
ml
Xm
.- V-1
L
/1:; Iw<
1-.-1
.- ZUJ
-m
~Parts rnarkedwiththis.signaresupplidwdh
uhighvottage exceeding 250V.
o
~Parts rnarlad with this sign have special
characteristics imptant for microwave leakage
When replacing any of these parts use only
manufacturers specified parts.
–3–
CONTROL
PRINTEO
CIRCUIT
BOARD
SI02
la
11 RL1
B
r—l
—
STEP 00WN
TRAN5FDRMER
Sloi
DOOR
SENSING
SWITCH
a
TIMER
!
TOUCH KEY
BOARO

6. TEST PROCEDURES AND TROUBLESHOOTING
CAUTION
—DISCONNECT THE POWER SUPPLY CORD
FROM THE WALL OUTLET WHENEVER RE-
MOVING THE CABINET FROM THE UNIT, PRO-
CEED WITH THE TESTS ONLY AFTER DIS-
CHARGING THE HIGH VOLTAGE CAPACITOR
AND REMOVING THE LEAD WIRES FROM THE
PRIMARY WINDING OF THE HIGH VOLTAGE
TRANSFORMER. (SEE FIGURE 3)
A. TEST PROCEDURES
COMPONENT
.— .-
MAGNETRON
HIGH-VOLTAGE
TRANSFORMER
—
CHECKOUT PROCEDURE
1)Check for resistance: Across the filament
terminals of the magnetron with an ohm-
meter on Rx 1 scale.
ohm-meter
2) Check for
Filament Windings
/
@
Q—
Figure 4
resistance: Between each flla.
ment terminal of the magnetron and the
chassis ground with an ohmmeter on
highest scale.
1
ohm-meter
1)Measure the resistance:
With an ohm-meter on Rx 1 scale.
a. Primary winding;
b, Filament winding;
c. Secondary winding;
2) Measure the resistance:
With an ohm-meter on highest scale.
a. Primary winding to ground;
b. Filament winding to ground;
,--- --*J j,
ohm-meter
Note: Remove varnish ot Figure
measured point.
6
Figure 3
RESULT
Normal reading.
Less than 1ohm
Normal reading:
Infinite ohms.
Normal readings:
Approximately 1.2 ohms.
Less than 1ohm
Approximately 72 ohms.
Normal readings:
Infinite ohms.
Infinite ohms.
–4-

COMPONENT CHECKOUT PROCEDURE RESULT
Measure the resitance:Across two terminals Normal reading:
with an ohm-meter on high est scale. Momentarily indicates several ohms, am
gradually returns to 10 meg-ohms,
Abnormal reading:
HIGH-VOLTAGE Indicates continuty or 10 meg-ohms frorr
CAPACITOR
um
the beginning.
including
BLEEDER’ Ohm-meter a
RESISTOR m
Figure 7
,—
Measure the resistance: Across two terminals Normal reading:
with an ohm-meter on Rx10,000 scale. Indicate about the middle position in one
direct (forward direction )and infinite
ohms in the reverse direction, using met[
((which is provided with a9-volt battery
Ohm-meter QNOTE
HIGH-VOLTAGE
“L
-Some digital meter may show over even
DIODE in aforward direction because low measur-
ing voltage of meter does not allow the
F&” 0 age diode,
meter current to pass through the high volt-
Abnormal reading:
Figure 8Indicates continuty or infinite ohms in boi
directions.
—
Measure the resistance: Across two terminals Normal reading:
with an ohmmeter on highest scale Indicates Infinite ohms In both directions
—
m
Abnormal reading.
Ohm-meter Indicates continuity In both dlrectlohs c
FUSE DIODE continuity In one dlrectlon and tnflnlt
ohms In reversed dlrectlon,
Figure 9
Measure the voltage: Between test points TP-41
TP.1, TP.2 or TP.3 and ground or between Test Point TP-1 TP2 TP.3 TP-5
TP.4 and TP.5. (See control clrcult board on
page 20) -5V -12V -30V 2.5V
Voltage DC Dc Dc Ac
CONTROL
CIRCUIT BOARD NOTE
-Proceed with the check of the step-
down transformer, to see if any one of
the mesuared values is different from
the specified values.
–5–

COMPONENT
TOUCH KEY
BOARD
CHECKOUT PROCEDURE
Measure the resistance between terminals of
FPC connector after removing it from SIOl.
(Figure 10) NOTE
–, When reconnecting the FPC connector,
make sure the holes on the connector are
properly inserted in hooks of the plastic
fastener in S101.
MATRIX CIRCUIT FOR
TOUCH KEYBOARD
FPC CONNECTOR
r———.—.—.—————————
c%=%=?-=?-:
Ir——
L-J
RESULT
Resistance
value
When checking “START” key, connect ohm
meter as iilust’ration below.
Oflm-meter
ToP
t/’
~)co
ocl
C2
C3
‘0
C3 f31
B2
Open
TERMINAL OF FPC CONNECTOR
Figure 10
CHECKOUT PROCEDURE FOR SWITCHES
Disconnect the lead wires from the switches and check for the continuity of the switches, connecting an ohm-meter to its ter-
minals.
—SWITCHES
(See Figure 1on page 1) CHECKOUT PROCEDURES DOOR OPEN
primary interlock,
o
0
Secondary interlock Terminals “COM” and “NO” +
Door Sensing
Interlock Monitor Terminals “COM” and “NC” m4°
DOOR CLOSED I
Wlw
CAUTION: After checking the switches, make sure that the interlock monitor switch is properly connected according to the
CIRCUIT DIAGRAM on page 3.
–6–

---- I-
..-— ---—
c
.-
d-.-.—- ---- —-— -. —. I---—- -
-—---.—— --—- -- -- —--- .
–7–

—
11
—— -- —-
Y
~J w~;
.—-——-———--?
-—-.---—
h’
.- 1
1
1-
-c I
_- __ —--

I
?
STEP SEQUEFJCE RESULT
—__._-—
1I
J
b
H.V
@@-@
.;,,—--—-J35\a&-\ Normal H.V
capacitor or
H,V. d!ode
mReplace Normal 1
IRuns
magnetron. magnetron. ,
w
transformer Resistance Check H.V. capacitor or HV. diode
e-l
OK with an ohm-meter after removing
lead wires. (See page 5) ~~kh Defective Replace H.V. Normal H.V. ~Runs
H.V. capacitor or capacitor or capacitor or I
Check resistance of H.V. diode H.V. d!ode, H.V. diode I
each wlndlng after
@e
,. ./-
removlng lead wires, ‘@
(See page 4). I
I
Resistance Replace H.V. Normal H.V. IRuns
Incorrect. transformer. transformer I
I
1
4) PROBLEM I
.OW microwave power
i( 3b
1
I
+
Normal
operation ‘
Check operallon of
blower motor when
START key IS
touched @-H-
NrI Temporarily short
operation across terminals
of thermal protectf
for magnetron and
thermal protector
for cavity by using
jumper lead.
@–-—---------& ;:.
I
I
@
Normal thermal ;_
Normal Replace thermal IRuns
protector for
operation protector for I
maanetron and thermal ~rotector for cavity. I
magnetron and
thermal protector
@*
I.’”
for cavity, I
GB
Reisstance : Replace blower Normal blower ,Runs
/—\ .
/\— Incorrect. motor. molor,
\I
kk I
I
No Measure resistance lo
I
operation _24D
@1’
1.”/
of blower motor
Approx. 240 ohms. fI@
I
Normal Replace control Normal contrcl ~Runs
resistance circuit board. circuit board. I
I
I