Briggs & Stratton 1938 User manual

FORWARD
This guide has been written and published by Briggs & Stratton Corporation to aid our dealers' mechanics and
company service personnel when servicing the products described herein.
It is assumed that these personnel are familiar with the servicing procedures for these products, or like or similar
products, manufactured by Briggs & Stratton Corporation. It is also assumed that they have been trained in the
recommended servicing procedures for these products, which includes the use of mechanics hand tools and any
special tools that might be required.
Proper service and repair is important to the safe, economical and reliable operation of all engine driven systems.
The troubleshooting, testing, service and repair procedures described in this guide are effective methods of
performing such operations.
We could not possibly know of and advise the service trade of all conceivable procedures or methods by which a
service might be performed, nor of any possible hazards and/or results of each procedure or method. We have
not undertaken any such wide evaluation. Therefore, anyone who uses a procedure or method not described by
the manufacturer must first satisfy himself that neither his safety, nor the safety of the product, will be
endangered by the service or operating procedure selected.
All information, illustrations, and specifications contained in this guide are based on the latest production
information available at the time of publication. However, Briggs & Stratton Corporation reserves the right to
change, alter, or otherwise improve the product at any time without prior notice.
Some components or assemblies of the product described in this guide may not be considered repairable.
Disassembly, repair and reassembly of such components may not be included in this guide.
Copyright ©2004 Briggs &Stratton Corporation
All rights reserved.
No part of this material may be reproduced or transmitted, in any form or by any means, electronic or
mechanical, including photocopying, recording or by any information storage and retrieval system, without prior
permission in writing from Briggs & Stratton Corporation.

Service&TroubleshootingGuide- HomeGeneratorSystems
Model1938(lOkW)TableofContents
MODEL 1938 (10KW)
GENERAL INFORMATION
SAFETY RULES
In the Interest of Safety
SafetyPractices
5
5
6
ACCESS TO THE GENERATOR 7
GENERATOR COMPONENTS 8
SYSTEM CONTROLS 9
GENERATOR CLEARANCES I 0
FUEL FACTORS I 0
Power Decreases at Altitude & Temperature 10
STARTING GENERATOR (NO LOAD) 10
Electrical Checks II
AUTOMATIC OPERATION
Sequence of Automatic Events
Utility Fail
Engine Warm-up Time Delay
Utility Voltage Pickup Sensor
Retransfer Time Delay
Engine Cool-down Timer
Testing The Automatic Transfer Switch
II
II
12
12
12
12
12
12
GENERATOR AC CONNECTION SYSTEM 12
CHECKING AUTOMATIC OPERATION 13
Stopping The System 13
Generator Load Tests 13
RECONFIGURING THE FUEL SYSTEM 14
SETTING THE EXERCISE TIMER
CIRCUIT INFORMATION
Power During Fault Conditions
Control Module Assembly (CMA)
LED Fault light Conditions
Resetting Fault Detection System
Trickle Charge Operation
14
15
15
15
16
16
16
FUEL SUPPLY 16
CONTROL MODULE CONNECTORS 17
TRANSFER SWITCH MODULE CONNECTORS 17
TROUBLESHOOTING
TROUBLESHOOTING LED FAULTS 20
Dead Unit /Low Battery Voltage:
(No Blink [ ] /One Blink [ • ]) 20
Check Battery: 20
Check Trickle Charging System: 20
Troubleshoot The Trickle Charging System: 20
Check The Step-down Transformer 21
Low Oil Pressure: (Two Blinks [ • • ]) 22
Low Oil Pressure
Troubleshooting Procedure: 22
Low Voltage: (Three Blinks [° ° • ]) 23
Low Voltage
Troubleshooting Procedure: 23
Engine Fails To Start: (Four Blinks [ .... ]) 24
Troubleshooting Procedure: 24
Engine Cranks But Fails To Start: 25
Gas Regulator 26
Check Ignition Spark: 28
Engine Fails to Crank: 28
Low Frequency: (Five Blinks [ ..... ]) 29
Low Frequency Troubleshooting
Procedure: 29
Over Speed: (Six Blinks [ ...... ]) 3 I
Over Frequency Troubleshooting
Procedure: 31
High Oil Temperature: (Seven Blinks
[....... ]) 32
High Oil Temperature Troubleshooting
Procedure: 32
I

Service & Troubleshooting Guide - Home Generator Systems
Model 1938 (lOkW) Table of Contents
GENERATOR ASSEMBLY
SPECIFICATIONS 36
Generator 36
Engine 36
ENGINE MAINTENANCE 37
Checking Oil Level 37
Changing Oil & Filter 37
Replacing The Spark Plugs 37
Service The Air Cleaner 38
Inspect Spark Arrester Screen 38
Engine Governed Speed 38
Valve Lash 38
Carburetor Adjustments 38
Engine Adjustment 39
I OKW RESISTANCE VALUES
System Interconnections
10kW Circuit Test Introduction
Checking The Stator Power Winding
Through The Harness
Checking The Battery Charge Winding
(BCW) Through The Harness
Checking The Excitation Circuit
Checking The Stator Power Winding
Checking The Battery Charge
Winding (BCW)
Checking The Rotor Winding
40
40
41
42
42
43
43
44
44
REMOVING THE MECCALTE GENERATOR
Roof Removal 46
Muffler Box Removal 46
Remove Fuel Line From Regulator 47
Alternator Bulkhead Removal 48
Removing The Generator 50
Blind End Cover Removal 50
Generator Isolation Mounts 50
Removing Stator
Mounting Hardware 50
Removing Rotor Through-Bolt
(Stay Shaft Bolt) 5 I
Removing The Rotor Assembly 52
Inspecting The Rotor Assembly 53
APPENDIX
CMA Schematic
Generator Wiring Diagram
50 Amp Wiring Diagram
200 Amp Wiring Diagram
200 Amp with Main Line Disconnect
Wiring Diagram
Transfer Switch Schematic
Oil Heater
240 Volt Battery Warmer
56
57
58
60
62
64
65
67
2

Service & Troubleshooting Guide - Home Generator Systems _& S_ra_fa.
Model 1938 (10kW) General Information _ _'_
GENERAL INFORMATION
MODEL 1938 (I 0KW)
3

_& St_a. Service&Troubleshooting Guide - Home Generator Systems
'_°_:_ Model 1938 (10k_)General Information
OTES
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4

Service&TroubleshootingGuideHomeGeneratorSystems
Model1938(10kW)GeneralInformation St_an _
SAFETYRULES
In the Interest of Safety _CAUTION: Indicates a hazard
which, if not avoided might
This manual outlines the construction, result in death or serious
function and servicing procedures of
the Briggs & Stratton Power Products®
Home Standby generator series. It is
structured for use by trained
technicians that are working in and
from a properly equipped shop.
Familiarity with the proper method of
using tools, measuring equipment and
injury.
CAUTION: When used without the 1
alert symbol, indicates a situation that
could result in damage to equipment.
NOTE: This notation is used
to inform you of a method,
workshop procedures are essential to reference or procedure that
performing successful maintenance and could assist with specific
repair on this equipment. operations or decisions.
Ensure that all specified tools and/or
equipment are available before [ u^7^Dr_ CVMm_,€ ^_r_ M=^_,_.€ ]
attempting to service this equipment.
For a detailed discussion of the
fundamental principles involved with
the physicsof electrical power
generation, refer to the Familiarization
and Troubleshooting Guide
(Publication #86262 Revision 3 or
later). This manual is available through
your Briggs & Stratton Central
Distributor.
Toxic Fumes Electrocution Explosion
Hot Surface Chemical Burns Fire
Safety Alert Symbols
The safety alert symbol (_) is used
to identify safety information about
hazards that can result in personal
injury. A signal word (DANGER,
WARNING, CAUTION) is used
with the alert symbol to indicate the
Read ExplosivePressure Goggles
Kick Back Disconnect Entanglement
potential severity of injury. In addition,
a hazard symbol may be used to
represent the type of hazard.
_ANGER: Indicates a hazard
which, if not avoided will result
in death or serious injury.
_ WARNING: Indicates a hazard
which, if not avoided could
result in death or serious
injury.
Spark Plug
,_ DANGER
•National electric code requires
generator to be properly grounded to
an approved earth ground. Call an
electrician for local grounding
requirements.
5
,_ DANGER
•When usinggenerator for backup
power, notify utility company. Use
approved transfer equipment to isolate
generator from electric utility.
•Use a ground fault circuit interrupter
(GFCI) in any damp or highly
conductive area, such as metal decking
or steel work.
•Do not touch bare wires or
receptacles.
• Do not use generator with electrical
cords which are worn, frayed, bare or
otherwise damaged.
•Do not handle generator or electrical
cords while standing in water, while
barefoot, or while hands or feet are
wet.
•Do not allow unqualified persons or
children to operate or service
generator,
_E WARNING
The engine exhaust from this product
contains chemicals known to the State of
California to cause cancer, birth defects,
or other reproductive harm.
,_ DANGER

_&St_on Service & Troubleshooting Guide ' Home Generator Systems
'_ Model 1938 (I OkW) General Information
Safety Practices
_k DANGER
,Donot allow any open flame, spark,
heat, or !it cigarette around battery
during, and for several m!nutes after
charging.
,Wea r protective goggles, rubber
apron, and rubber gloves.
_WARNING
•This generator does not meet U.S.
Coast Guard Regulation 33CFR-183 and
should not be used on marine
applications.
• Failureto use the appropriate U.S.
Coast Guard approved generator could
result in bodily injuryand/or property
damage.
•Do not attempt to modify the _/f
I_ unit or use it for any application
it was not designed for. If you
have any questions about your
generator's application, ask your
dealer or consult the factory.
Read these procedures carefully
and become familiar with your
generator set. Know its
applications, its limitations and
any hazards involved.
Never handle any kind of
electrical cord or device while
standing in water, while
barefoot, or while hands or feet
are wet.
•Do not use worn, bare, frayed
or otherwise damaged electrical
cord sets with any generator
set. Using a defective cord may
result in an electrical shock or
damage to the test equipment
and/or the unit.
These units require an adequate
flow of cooling air for their
continued proper operation.
Never operate or service any
unit while inside any enclosure
where the free flow of cooling
air into and out of the unit
might be obstructed. Without
sufficient cooling airflow, the
units quickly overheat, damaging
the generator and/or nearby
property.
Home Standby generators
produce a high voltage that can
cause an extremely dangerous
electrical shock. Avoid contact
with bare wires, terminals, etc.
Never permit an untrained
person to service or assist with
the procedures discussed in this
guide.
Never start or stop a unit with
electrical loads connected to
receptacles and with the
connected loads turned ON.
Start the engine and let it
stabilize before connecting any
electrical loads. Turn OFF and
disconnect all electrical loads
before shutting down any
generator.
• The manufacturer could not
IILLJII possibly anticipate every
circumstance that might involve
a hazard. For that reason,
warnings in manuals and
warnings on tags or decals
affixed to the units are not all-
inclusive. Do not handle,
operate or service a unit with a
procedure or method not
specifically recommended by the
manufacturer.
• This entire book is filled with
,_T-E important safety information
-please read it carefully.
6

Service&TroubleshootingGuide- HomeGeneratorSystems
Model1938(lOkW)GeneralInformation St_an_
ACCESSTO THEGENERATOR
The Home Generator System is equipped with an enclosure
that has four access doors (Figure I). The doors are named
for the significant component located behind them. Starting
with the side that has the fuel connection and proceeding
clockwise, the doors are named:
OIL SERVICE DOOR
AIR INTAKE DOOR
CONTROL PANEL DOOR
BATTERY DOOR
Each Home Generator System is equipped with three
identical keys. These keys fit the locks that secure the oil
service and control panel doors.
C:AUTiONi Do not operatethe
backup generator unlessthe OIL [
SERVICEand/or CONTROL PANEL I
doors are insta!led. Failure t ° doso wi!! ]
causeoverheating. ]
To remove an access door:
•Insert a key into the lock of the access door you wish
to remove and turn one quarter turn clockwise.
NOTE: The key is retained in the lock when the
locks are open.
• Grasp the door's lift handle and pull the door upwards
until the security pins are free of the lower base.
• With the security pins free, pull the lift handle outward
(away) from the unit while pulling the door down and
out of the upper door channel. The door will come
free of the generator enclosure.
The AIR INTAKE DOOR does not have locks or lift
handles. You must remove a locking screw found directly
above the center of the door. They are removed in the
same way the locking doors are removed. To secure these
access doors, replace the locking screws.
WARNING
burns.
To install an access door:
• Support the door by grasping the lift handle or louver.
Guide the top of the door into the generator
enclosure.
•Lift the door up into its upper channel until the security
pins clear the sill of the enclosure.
• Push the lower half of the door into the door recess
until it is flush with the sides.
• Seat the door by pushing it down until the rubber
coated security pins engage and the door rests on the
mounting sill.
• When installing a Iockable door, turn the key one
quarter turn counterclockwise and remove the key.

_& Stra_on Service & Troubleshooting Guide ' Home Generator Systems
'_ Model 1938 (I OkVV) General Information
GENERATOR COMPONENTS
°
°
/
Air Cleaner m Uses a dry type filter element and foam Exhaust Port m High,performance muffler lowers engine
precleaner to prevent dirt and dust from being drawn into noise to comply with most residential codes.
the engine, Oil DipStick--Used to check the engine oil level.
Battery--12 VDC, 33 Amp-Hour sealed battery provides" Oil Drain Hose m Provided to facilitate changing oil.
Control Panel Used for various test, operation and
PANEL on the next page. Unit Data Decal m Identifies unit by serial number,
8

Service&TroubleshootingGuide- HomeGeneratorSystems
Model1938(lOkW)GeneralInformation St_an_
SYSTEH CONTROLS
I 5 Amp Fuse -- Protects the Home Generator System •OFF position turns off running generator, takes system
DC control circuits. If the fuse has blown (melted open) or out of Automatic mode and resets any detected faults.
was removed, the engine cannot crank or start. Replace the • MANUAL position starts the engine but does not
fuse using only an identical BUSSAGC 15A fuse. disconnect from utility power. It is used for
AUTO/OFF/MANUAL Switch -- This three-position maintenance or diagnostic functions.
device is the most important control on the system and is
used as follows:
•AUTO position is the normal operating position. If a
utility power outage is sensed, the system will start the
generator. When utility power is restored and the
internal engine temperatures stabilize, it shuts off the
generator, and waits for the next utility power outage.
Circuit Breaker Protects the system from shorts and
other over-current conditions. Must be ON to supply
power to the Automatic Transfer Switch.
Diagnostic LED Used for troubleshooting operational
problems with the Home Generator System. All fault
conditions are described in the section LED Fault Light
Conditions.
While waiting, it maintains the battery with a trickle
charge. Hour Meter The hour meter records the total number
of hours the generator has been running and is used to
schedule maintenance tasks.
Set Exercise Switch -- Used to set the exercise cycle
start time and day-of-the-week. Exercise cycle only occurs
in AUTO mode.
9

e,StPa_n _Service & Troubleshooting Guide - Home Generator Systems
Model 1938 (IOkVV)General Information
Generator Clearances
The generator enclosure should be a minimum of 3 ft. (.9
meter) from combustible material. At least 3 ft. (.9 meter)
of access room all around the enclosure should be available.
The unit's exhaust port should be at least 5 ft. (I.5 meter)
from any building opening (window, door, vent etc.), and the
exhaust gases should not be able to accumulate in any
occupied area (Figure 4).
Fuel Factors
For proper engine function, the following fuel guidelines are
recommended:
•Clean, dry fuel, which isfree of moisture or any
particulate material should be used.
1
,_ CAUTION
•Do not operate the equipment if the fuel shut-off
valve is missing or inoperative.
• A manometer port should have been provided
(Figure 5).
Power Decrease at High Altitude or High
Temperature
Air density is lessat high altitudes, resulting in less available
engine power. Specifically, engine power will decrease 3.5%
for each 1,000 feet (300 meters) above sea level and I% for
each I0°F (5.6°C) above 77°F (25°C). Make sure these
factors have been considered when determining total
generator load output.
Starting The Generator (No Load)
Begin testing the system without any electrical loads
connected, as follows:
• Set the AUTO/OFF/MANUAL switch to OFF.
•Set the generator's main circuit breaker to its OFF
(open) position.
•Install the 15 Amp fuse in the control panel.
•Set the AUTO/OFF/MANUAL switch to MANUAL.
NOTE: If the Home Generator System has been
idle for an extended period, it may require that air in
the gaseous fuel lines be purged. This may take a few
minutes.
• The unit will go through its starting cycle.
• If unit failed to start, reset fault light and make sure the
fuel is ON.
• Listen for unusual noises, vibration or other indications
of abnormal operation. Check for oil leaks, evidence of
overheating etc. while the unit runs.
10

Service&Troubleshooting Guide - Home Generator Systems __& Sf_a, _
Model 1938 (I OkW) General Information _ _'_
Electrical Checks
With the AUTO/OFF/MANUAL switch set to OFF:
•Turn ON the main distribution panel circuit breaker
that supplies utility power to the Automatic Transfer
Switch.
_L DANGER
• Proceed with caution
• Use a true RMS AC voltmeter to check utility power
voltage across UTILITY CONNECTION lugs in the
Automatic Transfer Switch. Nominal line-to-line voltage
should be about 240VAC.
• Check utility power between one of the UTILITY
CONNECTION lugs and the neutral lug, then between
the other UTILITY CONNECTION lug and the neutral
lug. Nominal line-to-neutral voltage should be 120VAC.
• Set the generator's main circuit breaker to the OFF
position. Initial tests will be conducted at no-load
condition.
• Set the AUTO/OFF/MANUAL switch to MANUAL.
The engine should crank and start.
• Let the engine warm up for about five minutes to allow
internal temperatures to stabilize. Then, set the
generator's main circuit breaker to its ON (closed)
position.
DANGER
• Proceed with caution
• Connect a true RMS AC voltmeter and a frequency
meter to check generator output across GENERATOR
CONNECTION lugs in the Automatic Transfer Switch.
Voltage should be about 240VAC, frequency should be
62.0 - 62.5 Hz.
NOTE: If either parameter is outside these ranges,
perform the Engine Adjustments described on page
40.
Check generator output between one of the
GENERATOR CONNECTION lugs and the neutral lug,
then between the other GENERATOR CONNECTION
lug and the neutral lug. In both cases, voltage reading
should be about 120VAC.
• Set the generator's main circuit breaker to OFF.
• Set the AUTO/OFF/MANUAL switch to OFF. Engine
should shut down.
IMPORTANT: Do not proceed until you are
certain that generator AC voltage and frequency are
correct and within the stated limits. To obtain the
proper generator frequency, see Engine Adjustments
on page 40.
Automatic Operation
To select automatic transfer operation, do the following:
• Set the main distribution panel circuit breaker that
sends utility voltage to the transfer switch to ON.
• Set the AUTO/OFF/MANUAL switch to AUTO.
• Set the generator's main circuit breaker to its ON
position.
Sequence Of Automatic Events
The generator's control panel houses a logic control circuit
board. This control board constantly monitors utility power
source voltage. Should that voltage drop below 70%, control
board action will signal the engine to crank and start. After
the engine starts, the control board signals the transfer
switch to activate and connect the protected house circuits
to the Home Generator System.
When utility source voltage is restored above the 80%
voltage level, the control board signals the transfer switch to
transfer loads back to the utility source. After retransfer,
the engine is signaled to shut down after about Iminute for
cool-down.
II

_& Stolon Service & Troubleshooting Guide - Home Generator Systems
'_ Model 1938 (I 0kW) General Information
The actual system operation is not adjustable and is
sequenced by sensors and timers on the control board, as
follows:
Utility Fail
Utility voltage sensor senses when utility voltage is below
70% of nominal. Engine start sequence is initiated after 6
second delay.
Generator AC Connection System
A single-phase, three-wire AC connection system is used in
the Home Generator System. The stator assembly consists
of a pair of stationary windings with two leads brought out
of each winding. The two windings are connected together
in series, resulting in a fixed 240VAC, 60Hz output. Stator
output leads #1 Iand #44 are the two hot leads. The
junction of leads #22 and #33 form the neutral lead
(Figure 6).
Engine Warm-up Time Delay
Time delay to allow engine warm-up before transfer fixed
at 20 seconds or 50 seconds with optional cold weather
package.
Utility Voltage Pickup Sensor
Voltage pickup level is 80% of nominal voltage.
Retransfer Time Delay
Retransfer from standby to utility supply I 0 seconds after
utility voltage is above pickup level.
Engine Cool-down Timer
Enginewill run for 60 secondsafter retransfer.
Testing of The Automatic Transfer Switch
Turn the main service disconnect to the OFF position.
The automatic sequence will follow. To go back to utility
power, turn the main service disconnect to the ON
position.
--33
r22 1
33 22
|II Breaker
44 l II-----o_l-_c_ 240V
_- Neutral
/
120V
Circuit
Breaker
II 4
7Neutral
I
0
w
ToTransfer Switch
12

Service&Troubleshooting Guide - Home Generator Systems __& Sf_a, _
Model 1938 (I OkW) General Information _ _'_
Checking Automatic Operation
To check the system for proper automatic operation,
proceed as follows:
•Check that AUTO/OFF/MANUAL is set to OFF.
• Apply utility power to the UTILITY CONNECTION
lugs of the Automatic Transfer Switch by turning ON
the main distribution panel circuit breaker.
• Set the AUTO/OFF/MANUAL switch to AUTO. The
Automatic Power System is now ready for automatic
operation.
• Turn OFF the main distribution panel circuit breaker
that sends utility power to the automatic transfer
switch.
The engine will crank and start once the utility voltage drops
out and the sensor has timed out. After starting, the transfer
switch will transfer the circuit loads to the generator. Let
the system go through its entire automatic operation
sequence.
• With the generator output supplying its loads, turn ON
the main distribution panel circuit breaker that supplies
utility power to the transfer switch.
• After about 5 minutes of run-time, the automatic
transfer switch will transfer loads back to the utility
power.
• About one minute after re-transfer, the engine will shut
down.
This completes the test procedures for automatic operation.
The Home Generator System will now start automatically
when utility power is lost and will supply power to the
protected circuits in the home.
Stopping the System
To disable the power transfer system for maintenance:
• Ensure that utility power is ON and is supplied to the
UTILITY CONNECTION lugs of the transfer switch.
• Set the AUTO/OFF/MANUAL switch to OFF.
• Set the generator's main circuit breaker to its OFF
position.
Generator Load Tests
To test the generator with electrical loads applied, proceed
asfollows:
• Set the generator's main circuit breaker to OFF.
• Set the AUTO/OFF/MANUAL switch to OFF.
• Turn OFF the main circuit breaker, which supplies
utility power to the UTILITY CONNECTION lugs of
the Automatic Transfer Switch.
• Set AUTO/OFF/MANUAL switch to AUTO.
Engine should crank and start immediately.
• Let the engine stabilize and warm up for a few minutes.
• Set the generator's main circuit breaker to ON.
(Generator power is now supplied to the
GENERATOR CONNECTION lugs of the transfer
switch).
• Turn ON electrical loads. Apply the full rated output of
the selected circuits to the generator system.
• Use an accurate AC voltmeter to check generator
output voltage across the primary load lugs that supply
power to the protected circuits. Voltage should be
equal to or greater than 216VAC.
• Connect an accurate AC frequency meter across the
primary load lugs of the protected circuits. Frequency
should be 57-62.5 Hz.
• Let the Home Generator System run loaded for 20-30
minutes. Listen for unusual noises, check for excessive
vibration or other indications of abnormal operation.
Check for oil leaks, evidence of overheating etc.
• Turn the Main Distribution Circuit Breaker ON
(This supplies utility power to the UTILITY
CONNECTION lugs of the transfer switch).
The transfer switch should transfer back to utility, the
generator will cool down for I minute and then shut down.
13

_& Stra_on Service&Troubleshooting Guide - Home Generator Systems
'_ Model 1938 (I 0kVV) General Information
Reconfiguring The Fuel System
The engine of your Home Generator System isfactory
calibrated to run on natural gas (NG). It may also be
operated on liquefied petroleum (LP). There is no additional
hardware/equipment required to switch between either fuel.
However, LP fuel inlet pressure must be between I I and 14
inches water column.
To reconfigure the fuel system for LP use:
•Set the AUTO/OFF/MANUAL switch to OFF.
•Set the generator's main circuit breaker OFF.
• Remove the 15 Amp fuse.
Activate the fuel transfer solenoid as follows:
• Remove the Oil Service access panel.
• Connect the two-pin electrical connector shown in
figure 7. Use the short adapter cable, if supplied.
• Reinstall the Oil Service access panel.
• Reinstall the 15 Amp fuse.
• Set the generator's main circuit breaker ON.
• Set the AUTO/OFF/MANUAL switch to AUTO.
The system is now ready to operate automatically using LP
fuel. With a fixed main jet for LP gas, there is no need to
perform any engine adjustments for LP operation.
Setting Exercise Timer
The Home Generator System is equipped with an exercise
timer that will start and exercise the system once every
seven days. During this exercise period, the unit runs for
approximately 20 minutes and then shuts down. Electrical
load transfer does not occur during the exercise cycle
(unless a utility power outage occurs).
A switch on the control panel is labeled Set Exercise
(depicted on page 9). The specific day and the specific time
of day this switch is pressed is programmed into the control
board memory. This date and time is then used to
automatically initiate the system exercise cycle.
To perform the SET EXERCISE procedure:
• Choose the day and time you want your Home
Generator System to exercise.
• On that day and time, set the AUTO/OFF/MANUAL
switch to OFF.
• Press and hold down the SET EXERCISE switch. The
Diagnostic LED will turn on.
• Release the SET EXERCISE switch.
• Set the AUTO/OFF/MANUAL switch to AUTO.
Set Exercise is complete.
For example, if you press the SET EXERCISE switch on
Sunday morning at 10:00 AM, the unit will run an exercise
cycle the following Sunday at 10:00 AM.
NOTE: SET EXERCISE will only work if the unit is
in the Automatic mode and this exact procedure is
followed. The exerciser does not need to be re-set if
the 15 Amp fuse is removed or changed. The
exerciser will need to be re-set if the 12 VDC
battery is disconnected.
If you want to change the day and time the unit exercises,
simply perform the SET EXERCISE procedure on the exact
day and time you want it to take place.
14

Service&TroubleshootingGuide- HomeGeneratorSystems
Model1938(lOkW)GeneralInformation St_an_
Power During Fault Conditions
Whenever the Home Generator System is in an
uncorrected fault condition, the automatic transfer switch
resets to UTILITY POWER. This means that when utility
power is restored, it will automatically be applied to all the
circuits in the home.
Control Module Assembly (CMA)
The Control Module Assembly (CMA) is a printed circuit
board containing all the logic circuits that operate and
protect the generator. It is located inside the generator
enclosure behind the AIR INTAKE DOOR. It is the control
center of the generator. Its functions depend on the input
from various circuits throughout the standby installation.
Before replacing the CMA, all other circuits must be tested
to ensure proper operation. When a failure in the CMA has
been determined, the CMA must be replaced as a complete
assembly because its individual parts are not serviceable.
The functions of the CMA include:
•Battery Trickle Charge
• Set Exercise Timer
• Manual Start
• Sensing Utility Voltage
• Automatic Start, in event of utility failure
• Automatic generator power transfer.
• Automatic Engine Cool-Down Timer
• Fault Detection and Automatic Shutdown
• Fault Light Indication (Diagnostic LED)
To gain access to the CMA, refer to figure 8,
views A, B & C.
I. Remove the locking screw and the AIR INTAKE
DOOR (View A).
2. Remove the three screws holding the shield marked
Danger High Voltage (View B).
The location of the Control Module Assembly (CMA) is
shown in view C.
The CMA is connected to its various circuits through an 18-
pin connector that is mounted to the board itself.
When directed to measure an electrical value, the location
of the measurement is shown in the form of a picture and
the corresponding pin of the connector is shaded in a
graphic illustration that is specific to each test being
performed (Figure 9).
A detailed illustration of the entire connector, as well as the
functions of each individual pin, is given on page 17.
15

_& Stra_on Service&Troubleshooting Guide - Home Generator Systems
'_ Model 1938 (I OkVV) General Information
LED Fault Light Conditions
The generator may have to run for long periods of time
with no operator present. For that reason, the CMA is
equipped with sensing circuits that automatically shut down
the generator in the event of potentially damaging conditions
such as low oil pressure, high oil temperature, over speed,
and other conditions.
A light on the control panel (Figure 10), called the
Diagnostic LED will flash on and off in a series of blinks. The
blink pattern is repeated with a brief pause between each
set.
The number of blinks in the series indicates the detected
fault. These conditions are listed on the control panel and
below:
Number of LED Flashes Fault Description
Resetting The Fault Detection
System
An operator or technician must reset the fault detection
system each time it activates.
To do so:
•Place the AUTO/OFF/MANUAL switch in the OFF
position for 30 seconds or more.
• Place the AUTO/OFF/MANUAL switch in the AUTO
position.
If the fault is not corrected, it will be detected again and the
unit will again go into Auto Shutdown with the same fault
light indication.
Trickle Charge Operation
The trickle charge circuit isa Float Charger Type and is
designed to maintain the voltage of the battery. When utility
voltage is present and the unit is switched to the AUTO or
OFF position, the trickle charger will maintain the voltage
of a fully charged battery. It will not recharge a dead battery.
With the engine running, the trickle charge system is shut
down by the CMA and battery voltage is maintained by the
generator battery charge winding.
Refer to the Control System Schematic on pages 56-57.
Utility voltage isdelivered from the fuses in the transfer
switch through the terminal strip to the step-down
transformer with wires N I and N2. From the transformer,
24VAC is delivered to the CMA through Wires #224 and
#225. The CMA rectifies this 24VAC to 12VDC. This is
delivered to the battery via Pin #12, Wire #15, through the
15 Amp fuse, and on to the battery with Wire #13.
Fuel Supply
The following fuel supplies are necessary to ensure effective
generator operation (Figure I I).
I
2
3
4
5
6
7
Low Battery Voltage
Low Oil Pressure
Low Voltage
Engine Fail to Start
Low Frequency
Engine Overspeed
Oil Temperature High
Model Natural Gas* LP Vapor**
I/2 Load Full Load I/2 Load Full Load
1938(10kW) 84 162 34.19 65.81
* = Natura! Gas in cubic feet per hour
' = LP Vapor in gallons per hour!cubic feet per hour
16

Service&Troubleshooting Guide -Home Generator Systems __& Sf_an _
Model 1938 (I 0kW) General Information _ _'_
Control Module Assembly (CMA)
Connector Pins, Functions & Wire Numbers
(As seen from wire side of connector in the generator)
P-I_ P-I
Crank Disconnect @ 20VAC _1_ • • 4
W- 66al W-241
P- I I P-2 _1
"Set Exercise" H• • 4
W- 170 W-85_1
P-12 P-3 _
2VDC Output for Trickle Charger (Battery Power) _ • • 4
W-15
P-I_ P-4
Ground (GND) _ _ • •
W-0al
P. 14_1
Transformer (24VAC) _ _. •
W-22_P-15
W-225
Load Voltage (240VAC)
High Oil Temperature Shut-down q
P-16
W.TI
P.17 _
W-T_
P.18 _!
W-95al
•Pulse Voltage to LED Lamp
•Low Oil Pressure Shut-down
•Not Used
Not Used
P-5
• _ 12VDC to Starter Contactor
W-56
p.6 _1
• _ Ignition Shut Down
p.7 _
• _ Fuel Solenoid Valve & Hourmeter
W-14•
P-8
• _ 12VDC Input while A/O/M is in "Manual"
W.17
P-9
• I1_ 12VDC Input while A/O/M is in "AUTO"
W-239
P-Pin Number W - Wire Number AJO/M - AUTO/OFF/MANUAL GND - Ground
Transfer Switch Module Assembly (TSMA) Terminal Board
Connector Pins, Functions & Wire Numbers (As seen from inside the generator)
(As seen from inside to 100/200 AMP transfer switch only)
Transfer Switch "Utility" Coil _ _W-20SL_ J I
Transfer Switch "Stand.By. Coi! _ _ W.206 I_[ J4
17

_& St_a. Service & Troubleshooting Guide - Home Generator Systems
'_°_:_ Model 1938 (10k_)General Information
OTES
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18

Service & Troubleshooting Guide - Home Generator Systems __sggs& S_ra_fa.
Model 1938 ( I 0kW) Troubleshooting _ _'_
TROUBLESHOOTING INFORMATION
MODEL 1938 (I 0KW)
19