Order No. PHAT070510C3
Service Manual
Automatic Rice Cooker
SR-GA421/SR-GA281/SR-GA721
EXPORT
COOK
WARM
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SR-928 |
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Rice Cooking |
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Keep Warm |
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SR-GA421/SR-GA281 |
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SR-GA721 |
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Specification |
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Model |
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SR-GA421 |
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SR-GA281 |
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SR-GA721 |
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Detail |
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Country |
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HK |
SIN-DBD |
SIN-RBD |
MALAYSIA |
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HK |
MALAYSIA |
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SIN-DBD |
SIN-RBD |
USA |
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Power Source |
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220 V / 50 Hz |
230 V / 50 Hz |
220 V / 50 Hz |
240 V / 50 Hz |
220 V / 50 Hz |
240 V / 50 Hz |
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230 V / 50 Hz |
220 V / 50 Hz |
208 V / 60 Hz |
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Power |
Cooking |
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1400 W |
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950 W |
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2500 W |
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consumption |
Warming |
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47.5 W |
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Cooking capacity |
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5 ~ 23 L |
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5 ~ 15 L |
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3 ~ 7 L |
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Center thermostat |
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140 °C |
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working temperature |
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Keep warm temperature |
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More than equal to 80 °C (After 1 Hr. keep warm) |
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Thermal fuse specification |
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113 |
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169 °C |
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Dimension (mm) |
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367 |
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Width x Depth x Height |
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429 x 369 x 300 |
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x 295 |
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248 x 247 x 255 |
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x 305 |
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Weight |
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5.5 kg |
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3.6 kg |
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10.1 kg |
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Power Cord (approx.) |
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1.0 m |
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Accessories |
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Measuring cup, Steaming basket |
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Rice scoop |
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Specification subject to change without notice.
© 2007 Panasonic Home Appliance (Thailand) Co.,Ltd All rights reserved. Unauthorized copying and distrbution is a violation of law.
SR-GA421/SR-GA281/SR-GA721
CONTENTS
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Page |
1.SCHEMATIC DIAGRAM & WIRING DIAGRAM..................................................................... |
3-4 |
2.FUNCTION OF CENTER THERMOSTAT AND THERMAL FUSE......................................... |
5-6 |
3.TROUBLE SHOOTING GUIDE............................................................................................... |
7-8 |
4.TESTING PROCEDURE......................................................................................................... |
9-10 |
5.EXPLODED VIEW & PACKING VIEW (SR-GA421/SR-GA281)............................................ |
11-12 |
6.REPLACEMENT OF PARTS LIST & PACKING LIST (SR-GA421/SR-GA281).................... |
13-14 |
7.EXPLODED VIEW & PACKING VIEW (SR-GA721) .............................................................. |
15-16 |
8.REPLACEMENT OF PARTS LIST & PACKING LIST (SR-GA721)....................................... |
17-18 |
WARNING
This service information is designed for experienced repair technicians only and is not designed for use by the general public.
It does not contain warnings or cautions to advise non-technical individuals of potential dangers in attempting to service a product. Products powered by electricity should be serviced or repaired only by experienced professional technicians. Any attempt to service or repair the product or products dealt with in this service information by anyone else could result in serious injury or death.
IMPORTANT SAFETY NOTICE
There are special components used in this equipment which are important for safety. These parts are marked by 
in the Schematic Diagrams, Circuit Board Diagrams, Exploded Views and Replacement Parts List. It is essential that these critical parts should
be replaced with manufacturer’s specified parts to prevent shock, fire or other hazards. Do not modify the original design without permission of manufacturer.
2
SR-GA421/SR-GA281/SR-GA721
1. SCHEMATIC DIAGRAM & WIRING DIAGRAM
SCHEMATIC DIAGRAM (SR-GA421) |
WIRING DIAGRAM (SR-GA421) |
CAST HEATER
T.F.
(BIG)
N
(SMALL)
LAMP RESIST.
RICE COOKING NEON LAMP
E
LAMP RESIST.
Green INPUT
KEEP WARM NEON LAMP
SWITCH
Silicone Tube (Blue)
10˚
Cord Bush
L
MICA HEATER ASS’Y
N
±5˚
Silicone Tube (Brown)
Cord Wire Earth (Green)
Silicone Tube (Green)
Switch Lead Wire (Blue) |
Twist two time |
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Lever Earth Lead Wire (Green) |
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Thermal Fuse Wire (Brown) |
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Thermal Fuse Wire (Gray) |
Lamp Lead Wire C (Brown) |
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Lead Wire (Orange) |
Lamp Lead Wire B (Gray) |
Twist one time |
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Lamp Lead Wire A (Orange) |
SCHEMATIC DIAGRAM (SR-GA281) |
WIRING DIAGRAM (SR-GA281) |
T.F. T.F. Gray Cast Heater
Blue
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N |
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Lamp Resistor |
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E |
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Rice Cooking Neon Lamp |
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Lamp Resistor |
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Input |
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Green |
L |
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Keep Warm Neon Lamp |
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Switch |
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Brown |
Mica Heater Ass’y |
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After ass’y, Mica Heater Ass’y must not overlie the Outer Case of Center Thermostat.
After ass’y, gap between terminal and mica heater case must be more than 4 mm.
Glass tape 20 x 20 mm.
Silicone Tube (Brown) |
1 |
0˚ |
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± |
Silicone Tube (Blue) |
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5˚ |
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Cord Bush |
Water guard |
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After assembly Mica Heater case
Must no touch the terminal of cast heat.
N
Cord Wire Earth (Green)
Silicone Tube (Green)
Thermal Fuse Wire (Blue)
Lever Earth Lead Wire (Spiral Green)
Wiring Lead Wire (Brown)
Lamp Lead Wire B (Gray)
Thermal Fuse Wire (Gray)
Lamp Lead Wire C (Brown)
Twist one time
Lamp Lead Wire A (Red)
3
SR-GA421/SR-GA281/SR-GA721
1. SCHEMATIC DIAGRAM & WIRING DIAGRAM
SCHEMATIC DIAGRAM (SR-GA721)
Blue
N
1.F.T 2.F.T
E
INPUT
Green
L
Brown
CAST HEATER
(SMALL)
(MIDDLE)
(BIG)
LAMP RESIST.
RICE COOKING NEON LAMP LAMP RESIST.
KEEP WARM NEON LAMP
SWITCH
MICA HEATER ASS’Y
WIRING DIAGRAM (SR-GA721)
Cord Wire Earth (Green)
Keep warm lamp lead (Red)
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0 |
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1 |
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Cord Wire Blue (N)
Cord Wire Brown (L)
Heater lead wire B (grey)
Thermal fuse lead wire (Blue) |
User position |
Thermal fuse lead wire (Grey) |
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Cathode lead wire (Brown)
Red
Brown
Grey
Heater lead wire A (Red)
Heater lead wire C (Brown)
4
SR-GA421/SR-GA281/SR-GA721
2. FUNCTION OF CENTER THERMOSTAT AND THERMALFUSE
A. Center Thermostat
The center thermostat senses when the bottom of the rice cooker pan reach 134°C ± 6°C. And it’s action turns off the cooking cycle, and starts the warming cycle.
Center thermostat construction |
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Metal |
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Cook switch button |
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Magnet |
Inner spring |
Outer |
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Cooking heater |
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Rod Inner spring |
spring |
Switch lever |
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Figure 1 |
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NC |
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(Cooking Position) |
(Warming or Off Position) |
Micro switch |
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C |
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Refer to these figures showing the center thermostat construction and cooking position. As the metal is heated, its ability to be attracted by the magnet decreases.
Finally, the inner spring pressure becomes stronger than the magnetic pull and the metal and magnet will pop apart. The rod activates the switch lever which causes the auxiliary lever to press the micro-switch button into the warming cycle.
B. Switch-On Preventive System |
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Metal |
Thermostat surface |
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Cooking heater |
Inner spring |
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Outer spring |
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Magnet |
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Thermostat case |
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10mm |
Cook switch button |
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Rod |
Switch lever |
Auxiliary lever |
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Micro switch |
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This is design to prevent the rice cooker from being turned on without the pan placed into position.
1)Normally when the pan is inserted properly into the rice cooker, the pan will depress the center thermostat. The center thermostat outer spring will be compressed. In this case when the switch button is depressed, the following will happen:
a.The auxiliary lever will release the micro-switch button. This puts the micro-switch in the cook position.
b.The switch lever will push the rod which will allow the magnet to meet with the metal.
c.When the rice is cooked and the proper temperature has been reached 134°C ± 6°C, the metal and magnet will pop apart as described in the center thermostat operation above.
d.The rod will push the switch lever and cause the auxiliary lever to depress the microswitch button. This puts the micro-switch in the warming position.
2)When the pan is not in place within the rice cooker, the center thermostat is not depressed.
a.In this condition, the outer spring is not compressed within the center thermostat preventing the metal from reaching its normal operating position.
b.When the switch button is depressed, the switch lever and auxiliary lever work as above but the magnet cannot come in contact with the metal to hold the switch lever in the cook position. This happens because the switch lever hits the thermostat case and cannot push the rod, with the magnet attached, all they way up to meet with the metal.
c.When the pressure is taken off the switch button, the switch lever releases immediately to the open or warm positions.
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SR-GA421/SR-GA281/SR-GA721
2. FUNCTION OF CENTER THERMOSTAT AND THERMALFUSE
C. Thermal Fuse
The thermal fuse is used to open the circuit to the cooking heater when the temperature has gone unusually high. This happens in cases such as incomplete contact between the heater and pan or if the switch buttons is forced to stay on keeping the heater energized abnormally.
This fuse is not a resetting device and must be replaced after openning.
Whenever replacing the fuse make sure the protective cover is placed over all exposed wiring.
Cause of Fusion
[A] Improper contract between heater and pan
Cause
Remedy
Pan collar or deformed
Foreign matter adhering |
Body dented or deformed |
Pan bottom dented or |
Heater surface deformed |
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deformed |
or corroded |
Remove foreign matter |
Repair or replace body. |
Replace pan. |
Replace cooking heater. |
by of (-) screw-driver, |
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etc., and then polish with |
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= 320 water paper while |
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wetting it with water. |
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[B] Forced application of current
Cause
Remedy
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Chopstick, wooden |
Switch lever deformed |
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piece, etc. inserted onto |
or maladjusted, causing |
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cooking button. (continu- |
continuous application of |
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ous application of current) |
current. |
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Inserted to prevent ear- |
Repair or replace parts. |
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lier turning off? Refer to |
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cause in (a) above. |
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When fusion takes place, check the cause, set right the faulty section, and be sure to use replacement parts.
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