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GE Appliances Service Training
________________________________________________________
TECHNICIAN
SERVICE MANUAL
Dryer
MODEL:
DISR473TWW
CIWE1001E
FEBRUARY 2000
CAUTION !
DISCONNECT POWER CORD
BEFORE SERVICING THIS APPLIANCE!
RECONNECT ALL GROUNDING DEVICES
IMPORTANT SAFETY NOTICE !
This service information is intended for use by
individuals possessing adequate backgrounds of
electrical, electronic and mechanical experience.
Any attempt to repair this major appliance may
result in personal injury and property damage. The
manufacturer or seller cannot be responsible for
the interpretation of this information nor can it
assume any liability in connection with its use.
THE MANUAL COVERS THE
FOLLOWING MODELS
MODEL# COUNTRY
DISR473TWW AUSTRALIA
N/A BANGLADESH
N/A CHINA
N/A HONG KONG
N/A INDIA
N/A INDONESIA
N/A JAPAN
N/A KOREA
N/A MALAYSIA
N/A PAKISTAN
N/A PHILIPPINES
N/A SINGAPORE
N/A TAIHITI
N/A TAIWAN
N/A THAILAND
N/A VIETNAM
I. SPECIFICATION
Page 4
ITEMS SPECIFICATIONS
Colour WW, AA
Dimensions (Inches) (W x H x D) 27 x 42 x 28¼
Total # of Cycles 7
Electrical 240 VAC, 50 Hz, 20 amps
Timed Dry (Min) 80
Capacity (kg) 8
Heat Selection 4
Page 5
II. THEORY OF OPERATION
2.1 How a Dryer Works
All dryers, whether gas or electric, operate
according to the same principle they remove
moisture from damp clothes by bringing the
clothes in contact with a flow of heated air.
Mechanically the clothes must tumble to expose
all of their surfaces to heat, and the heated air
must be circulated within the dryer and then
vented.
Switches, timers and thermostats regulate the
air temperature and duration of the drying cycle.
When the start button is activated with the dryer
door closed, the motor is activated. The motor is
connected to the drum by a drive belt. This
drive belt rotates the drum through a pulley
system attached to the motor shaft. The drum
itself is supported by a bearing and slides at the
front.
2.2 Axial Air Flow
Air is pulled into the cabinet from the rear, and
drawn up across the heaters located behind the
drum. This hot air is pulled through the drum
rear, across the clothes load, through the lint
filter and down the trap direct into the blower.
From the blower the air is pushed out the
exhaust system.
In electric dryers, the heat source is not
energized until the drive motor start turning.
Both the timer and thermostats energize coiled
resistance heaters. The temperature selector
switched control the number of heaters
energized.
Page 6
II. THEORY OF OPERATION
2.2 Axial Air-Flow Dryers
Page 7
II. THEORY OF OPERATION
2.2 Air Flow Diagram
Page 8
III. GROUNDING EQUIPMENT
IF THE DRYER IS SUPPLIED WITH A FLEXIBLE POWER CORD
Plug the cordset into its own separate grounded out. Do Not, UNDER ANY CIRCUMSTANCES, CUT OR REMOVE
THE GROUND PRONG FROM THE POWER CORD.
Page 9
IV. DRYER CONSTRUCTION AND SERVICE
Control Panel : Provide access to timer & switches.
Service : Remote four #15 Torx screws from top. Switches & timer are tab interlock. The timer is
not technical serviceable.
Cabinet : 4 x Parts
2 - Side painted panels with knowckouts for side exhaust
L - Shape galvanized steel chassis : Back - Base Front
BACK with louvers for air entry and Service access panel
BASE with leveling legs and knockout for buttom exhaust
Service : All cabinet parts are hold together by screws.
Top : Upswept, galvanized steel, power painted
Service : Remove two screws in door opening and lift it up
Door : Embedded in front cabinet
Two parts : Front door and inner door hold by screws
Plugs 2 hinges and a latch strike
Service : Just loose hinge screws in key holes
Front : One-piece construction
Outside : Filter snapped in
Inside : Latch
Front seal and felt
Drum slide
Trap duct
Service : Front - Remove the top
Remove screws on the inside right and left of cabinet
Lift it up from the two supports it rest on at the bottom
Note : The drum must be supported by one hand while removing the front.
Disconnect wires from door switch
Front Seal - Clip on trap duct
Front Felt - Clip on door opening flange
Trap Duct - Clip on door opening flange
Drum Slides - The teflon slides are removable
There are two color slides (grey & white) - do not mix
Do not lubricate the slides
Page 10
IV. DRYER CONSTRUCTION AND SERVICE
Drum : 7 x Parts
Belt
One-piece drum (front Wrapper Rear)
3 baffles
Diffuser
Shaft
Bearing
Service : Drum Removal Remove belt from idler pulley
Release idler arm (belt tension system)
Lift up the drum or through port at right
Reach under the drum behind the motor
Pull idler arm at the pulley end down
Hook the idler end on the motor mount bracket
The bracket has a hook that will hold idelr arm and allow to easily place or remove the belt
over the idelr pulley and motor pulley.
Slide the drum out
Baffles Hold with 3 screws
Diffuser Secure with 4 x Torx # 15 screws
Shaft bracket Same screw as the diffuser. Be careful when re-installing the drum that
the bearing and washers are in place.
Motor / Blower : Motor
Motor mount bracket
Blower housing
Blower
Idler spring
Service : Motor, blower, idler swith are all mounted on motor bracket.
Unscrew the two long screws (9 cm) securing the motor bracket to the blower housing and
two 3/8 hex. Screws through the base.
Heater : Heater assembly
Hi limit thermostat at 2:00 oclock
Safety control thermostat
Control thermos
Service : Heater - The heater is not reastringale and must be replaced as a complete part.
Its mounted with 4 screws.
Thermostat - Secure with screw and tab.
Page 11
V. ELECTRIC CLOTHES DRYER CONTROLS (SCHEMATIC)
Page 12
VI. MACHINE FUNCTION
7.1 Drive System
The drum is rotated counterclockwise, as
viewed, from the front, at a speed of 47-50 RPM.
Belt tension is maintained by a idler pulley and
driven by a pulley attached to the rear motor
shaft.
7.1.1 Belt Alignment
Proper alignment of the drive belt must
be maintained to eliminate:
i. Belts Off Riding off the rear of
the motor pulley.
ii. Broken Belts or Fast Tumble
Speed resulting from the belt
riding forward on the motor pulley,
turning the drum faster, and
ultimately being damaged by the
motor pulley set screws.
If a damaged belt is found, inspect the
motor pulley grooves for smoothness
and remove any belt threads that may
have been wound around the pulley.
After the new belt is installed, check
the belt alignment as follows.
7.1.2 Belt Alignment Check
Remove the rear cabinet access
panel. Rotate the drum by hand
clockwise and then counterclockwise
several revolutions. Observe the
tracking or position of the belt on the
idler pulley. If the belt tracks near
either the front or rear edge of the
idler pulley, bend the idler arm as
shown to center the belt on the idler
pulley.
Note : The belt ridges and pulley
grooves must match.
(Top View)
DRIVE SYSTEM ALIGNMENT
7.1.3 Motor / Blower Removal - All
Models
Remove drum, remove blower
housing screws on cabinet front.
Release rear motor mounting clip and
remove motor / blower assembly for
service.
Page 13
VI. MACHINE FUNCTION
7.2 Timer Cycles
7.2.1 Timed Cycle
When TIMED drying is selected, the
drying time in minutes is set on the timer
dial. The fabric type or temperature is
set with the selector switch. Actuating
the safety start switch starts the dryer
and timer operation begins, as shown in
the simplified circuit below.
If the timer dial is not in an OFF zone,
Switches TB, TC, and TT, TX are closed.
Drying temperature is controlled by the
thermostat system. See Thermostats for
explanation.
7.2.2 Automatic Cycle
When automatic drying is selected, the
timer dial is set in the automatic zone. The
fabric type or temperature is set on the
selector switch. Actuating the safety start
switch starts the dryer.
240V is applied to the heaters, and drying
begins. The timer does not operate at this
time because it is bypassed by the TB, TA
timer switch and the thermostats which are
all closed. The TT, TH timer switch is open
when automatic drying is selected. When
drying temperature is reached, the drum
outlet thermostat opens. This removes the
bypass circuit around the timer, and a new
series circuit is established. The new
circuit is the timer, the 2000 ohm resistor
and the heraters across 240V. The
hearters being less than 10 ohms can be
disregarded, leaving the timer and the
resistor to divide the voltage. The
impedance of each being approximately
the same allows the timer to see 240 volts,
and timer operation begins.
When the dryer cools down to the reset
point of the drum outlet thermostat, the
drum outlet will close, bypassing the timer
and re-establishing the heater circuit. This
alternative action of heat and timer
operation continues until the end of the
cycle when timer switch TB, TA opens,
preventing additional heat (cool down) and
providing continuous timer operation into
the OFF zone. The cool down period is 8-
10 minutes.
Page 14
VII. THERMOSTAT DATA
THERMOSTAT
TEMPERATURE
°
F TEMPERATURE
°
C
OPEN CLOSE OPEN CLOSE
HIGH DRUM OUTLET
135
±
5 120
±
557
±
349
±
3
LOW DRUM OUTLET
125
±
5 115
±
552
±
346
±
3
THERMO HI-LIMIT
RIGHT
315
±
10 250
±
15 157
±
6 121
±
9
SAFETY LEFT / CONTR.
INLET
210
±
5180
±
7 99
±
382
±
4
Page 15
VIII. CIRCUIT DIAGRAM
Page 16
XI. NEW MODIFIED SCHEMATIC
Page 17
X. NEW RELOCATION OF BIASED OUTLET THERMOSTATS
THERMOSTAT
TEMPERATURE
°
F TEMPERATURE
°
C
OPEN CLOSE OPEN CLOSE
DRUM OUTLET
135
±
5 125
±
557
±
352
±
3
BIASED CONTROL
INLET
210
±
5180
±
5 99
±
3 85
±
3
THERMO HI-LIMIT
RIGHT
315
±
10 250
±
15 157
±
6 121
±
9
SAFETY LEFT
210
±
5180
±
7 99
±
382
±
4
Page 18
XI. GENERAL TROUBLESHOOTING GUIDE
THIS IS GENERAL TROUBLESHOOTING AID AND MAY NOT COVER ALL SYSTEMS ON A PARTICULAR MODEL
* See Schematic for Proper Switch Connections
1. Heater coils resistance is shown on wiring schematic (on reverse side of this sheet). Check for infinite resistance
between any heater terminal and dryer cabinet. Heater failure could result from low air flow caused by improper
sealing, kinded or excessive ducting, or excessive line voltage.
2. Other factors contributing to long dry times, or clothes condition : load size, large bulky items, ambient temp., room
size (if not exhausted outdoor), washer spin speed, washer rinse temperature.
3. Small loads : Less than 3 lbs. If not treated with destaticizer could develop a static charge if overdried and cling to
drum surface (no tumble) causing wrinkles, shrinkage, or melting. Use a fabric softener (washer or dryer) or add 2
large bath towels to act as buffer when drying.
Page 19
XII. SYMPTOM CHECK CHART
SYMPTOM CHECK
Motor does not operate
-
Fuse open in power supply lines.
-
Start switch (backsplash) defective.
-
Door switch inoperative.
-
Timer contacts (B-C) inoperative.
-
Overload protector in motor inoperative.
-
Open circuit in harness.
-
Motor defective.
-
Motor start switch defective.
-
Belt switch
Drum does not rotate
-
Broken, loose, or worn belt.
-
Motor pulley loose.
-
Drum binding. Check exterior of drum for objects or
excessive pressure of felt seal on drum. Spray
drum edge and slides with silicone.
Dryer runs continually
-
Operating thermostat inoperative.
-
Timer motor inoperative.
-
Circuit to heaters open or heaters open.
-
Open resistor.
Noise and vibration
-
Motor mounting bolts loose.
-
Pulley loose.
-
Blower rubbing against scroll.
-
Blower vanes broken.
-
Worn teflon slides.
-
Worn drum shaft teflon bearing.
-
Loose article in drum.
-
Harness rubbing on drum.
-
Lint build-up on blower or in scroll.
-
Foreign object between drum and front felt seal.
Cycle completion Signal inoperative
-
Timer contacts T S inoperative.
Page 20
XII. SYMPTOM CHECK CHART
SYMPTOM CHECK
Clothes damp at end of cycle
-
Dial setting for type of load incorrect.
-
Lint trap clogged.
-
External ducting clogged.
-
For very small loads, add two or three bath towels
as buffers, or set a longer time selection on dial.
-
Heat switch setting incorrect (Timed-dry models)
-
4000 ohm load-compensating resistor inoperative
(Auto cycle dryers)
-
Control thermostat defective.
-
Clothes excessively wet when put in dryer.
-
(Timed dry operation) Dryer installed in location
where temperature is too low (under 50
°
F)
Clothes wet at end of cycle
-
Heater element burned.
-
Centrifugal switch in motor inoperative.
Excessive drying time
-
Clothes excessively wet when put in dryer.
-
Thermostat iniperative
-
Lint trap, or external ducting clogged.
Clothes overdry or wrinkled
-
Incorrect timer setting used.
-
Operating thermostat inoperative.
-
One heater coil open.
-
(Auto cycle operation) Dryer installed in location
where temperature is too low (under 50
°
F)
Shrinkage
-
Clothes do not shrink more in a dryer than in line
drying. Clothes do shrink faster. Example : If an
article shrinks all that it is going to in 12 washings
and line dryings, it may reach its full amount of
shrinkage in only 3 or 4 dryer dryings.
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