Samsung SMH1927 User manual

SMH1927 2/17/2012 1
Fast Track Troubleshooting
Publication # rsSMH1927 Revision Date 2/13/2012
Model: SMH1927***/XAA
IMPORTANT SAFETY NOTICE –“For Technicians Only” This service data sheet is
intended for use by persons having electrical, electronic, and mechanical experience
and knowledge at a level generally considered acceptable in the appliance repair trade.
Any attempt to repair a major appliance may result in personal injury and property
damage. The manufacturer or seller cannot be responsible, nor assume any liability for
injury or damage of any kind arising from the use of this data sheet.
SUPPORT INFORMATION
Training —Plus One http://my.plus1solutions.net/clientPortals/samsung/
Help —GSPN http://gspn3.samsungcsportal.com
Samsung Product Support TV http://support-us.samsung.com/spstv/howto.jsp
Customer information videos and chat programs. Programs for Fridges, Laundry, Ranges & D/W
Oven Thermal Cutout
The oven thermal cutout (Cavity TCO) is located on the top side of the oven cavity beside the exhaust duct with a tem-
perature rating of 248°F (120°C) and is NOT resettable.
Hood Thermal Cutout
This cutout will protect the touch control from excessive heat by turning the vent fan on at low speed. If the surface units
of the range are used for long periods of time heat will build up and could damage the microwave control. In order to pre-
vent this, a thermal cutout is installed on the duct behind the control. This cutout will close (158°F/70°C - vent fan ener-
gized) and open (104°F/40°C - vent fan de-energized) depending on temperature.
Magnetron Thermal Cutout
The magnetron thermal cutout is located above the leads to the magnetrons. It is designed to prevent damage to the
magnetron if an overheated condition develops in the tube due to cooling fan failure, obstructed air ducts, dirty or
blocked air intake. Under normal operation, the magnetron thermal cutout remains closed. However, when abnormally
high temperatures are reached within the magnetron, the magnetron thermal cutout will open at 302°F (150°C) causing
the oven to shut down. After the temperature drops to 140°F (60°C) it will reset and cooking will be able to resume.
Bottom Thermal Cutout
During a fire on the stove the heat could be intense enough to close the Hood Thermal Cutout and force the fan to run.
While at moderate high temperature we do want it to run, however during a fire it is advantageous to NOT have the vent
fan running. So if a fire were to start on the stove top the Bottom Thermal Cutout would open at 248°F (120°C) and re-
move all power to the microwave oven. This cutout is NOT resettable.
Error Code Cause and countermeasure
-SE- Key short error (10 sec.). Replace assy. control
panel or smart board.
E-11
Sensor open error. Check unplugged sensor, wiring
or smart board. If necessary, replace sensor. If
error code appears when starting sensor function,
replace smart board.
E-12
Sensor short error. Check shorted sensor or smart
board. If necessary, replace sensor. If error code
appears when starting sensor function, replace
smart board.
E-13
Sensor T1 max time error. Check sensor. If neces-
sary, replace sensor. If error code appears when
starting sensor function, replace smart board.
SENSOR TEST (QUICK TEST)
1. With 2 fingers touch and hold the following pads at
the same time:
Auto Defrost and Popcorn
2. Observe diagnostic number in display (Numbers
approximate).
● 15-185 (Normal-verify with “detection test” )
● 213 or Higher (Sensor failed to open, sensor un-
plugged, wiring or smart board).
● Less than 6 (shorted sensor or smart board).
NOTE: Only heater terminals (Black and Red leads)
can be checked with an ohmmeter (30Ω).
CAUTION: DO NOT ATTEMPT TO CHECK SENSOR
TERMINALS (White and Orange leads).
♣ CAN DAMAGE SENSOR.
TO TEST BLOWER WINDINGS: 1. Disconnect power and remove grill. 2. Open control panel and discharge
capacitor. 3. Continuity test across the two wires of the run capacitor should be approximately 125 ohms of resistance.
This test allows you to read across all three windings at the same time. Thermal protector reads 0 ohms from white to
orange.

SMH1927 2/17/2012 2

SMH1927 2/17/2012 3
CN02 Pwr & Relay
3-(CN201-1) Vent High
5-(CN201-1) Vent Mid
7-(CN201-1) Vent Low
9-(CN201-1) Vent boost
11-(CN201-1) In rush
Main PCB
CN201 Power
1 Line 1
3 Main
5 Cook top lamp
7 TT
RY203 MW
Power Low
RY209
Vent
High
RY204
Main
Relay
RY205
Night
Relay
RY206
Bright
Relay
Door Interlock Ass’y
CN401 Door Connector
1 Door sw 12vdc
3 Door sw
4 Gnd
5 Hood TCO The fuses are located on the noise filter.
1. Disconnect power and remove grille and Assembly
Control Box.
2. Replace the fuse.
3. When 20A fuse blows out by the operation of interlock
monitor switch failure, replace the primary interlock
switch, secondary interlock switch, door sensing switch,
interlock monitor switch and power relay.
4. When the above four switches operate properly, check
if any other part such as the control circuit board, blower
motor or high voltage transformer is defective.
CN701
Membrane Sw RY210
Vent
Mid
RY207
TT
RY202 MW
Power High
CN301
Gas Sensor
RY211
Vent
Low
RY212
Vent
Boost
RY201
In Rush
Microwave cover assembly
The front of the top cover has flanges that must fit inside the front frame and vent, and the bottom goes above the bot-
tom cover. Start with the left side and hold in place with one screw once engaged. Leave the display loose so you can
see that the right side is engaged properly. Then mount display and the vent, ensuring the vent engages the flange.

SMH1927 2/17/2012 4
WARNING: It is critical to route wires and
wire harness identical to the way they were,
to prevent electromagnetic interference caus-
ing possible fault codes.
Procedure for measurement of microwave energy leakage
1. Pour 275±15cc of 20±5°C(68±9°F) water in a beaker which is
graduated to 600cc, and place the beaker in the center of the oven
2. Start to operate the oven and measure the leakage by using a mi-
crowave energy survey meter.
3. Set survey meter with dual ranges to 2,450MHz.
4. When measuring the leakage, always use the 2 inch spacer cone
with the probe. Hold the probe perpendicular to the cabinet door.
Place the spacer cone of the probe on the door and/or cabinet door
seam and move along the seam. The door viewing window and the
exhaust openings moving the probe in a clockwise direction at a
rate of 1 inch/sec. If the leakage testing of the cabinet door seam is
taken near a corner of the door, keep the probe perpendicular to
the areas making sure that the probe end at the base of the cone
does not get closer than 5 cm to any metal. If if gets closer than 5
cm, erroneous readings may result.
5. Measured leakage must be less than 4mW/cm2 after repair and
adjustment.
Maximum allowable leakage is 5mW/cm2. 4mW/cm2 is used to allow
for measurement and meter accuracy.
Microwave Cooking Wattage Test
Safety precautions
High Voltage Warning Do not attempt to
measure any of the high voltages --this in-
cludes the filament voltage of the magnetron.
High voltage is present during any cook cycle.
Before touching any components or wiring,
always unplug the oven and discharge the
high voltage capacitor
Some semiconductor (“solid state”) devices
are easily damaged by static electricity. Such
components are called Electrostatically
Sensitive Devices (ESDs). Examples
include integrated circuits and field-effect
transistors. Immediately before handling any
semiconductor components or assemblies,
drain the electrostatic charge from your body
by touching a known earth ground.
Temp Rise Output Temp Rise Out-
put
5194 23 891
6232 24 930
7271 25 969
8310 26 1007
9349 27 1046
10 387 28 1085
11 426 29 1124
12 464 30 1162
13 504 31 1201
14 542 32 1240
15 581 33 1279
16 620 34 1317
17 659 35 1356
18 697 36 1395
19 736 37 1434
20 775 38 1472
21 814 39 1511
22 852 40 1550
Fill a 1000ml plastic room temperature container with cool tap water,
temperature of the water should be 55-65 degrees
Stir water with a thermometer and record the water temperature, remove
thermometer.
Place the container in the center of the lowest shelf or center of the
bottom of the microwave.
For units less than 1550 watts, operate the oven on high for exactly 63
seconds.
Using the thermometer, stir the water to check the temperature of the
water.
Subtract the starting temperature from the final temperature; this will be
the temperature rise.
NOTE: Check line voltage under load, lower line voltage will lower
the power output.
M/W Power
1000
Watts
M/W Weight 55 Lbs
Primary low 0.43Ω
Primary high 0.39Ω
Secondary 125
Filament 0.0Ω
Turntable
Motor
120Ω
Fan Motor 45Ω
Vent, at run
cap (checks
all windings)
125Ω
Motors
M/W Information
Specifications
High Voltage
Transformer