Generac Power Systems 940, 941 User Manual

SERIES IMPACT 36 PLUS

Models 940 & 941

SERVICE

MANUAL

Manual Part No. D1752

Printed in U.S.A

First Edition Issued - 11/01/00

P.O. Box 297 • Whitewater, WI • 53190

Phone: [phone] Fax: [phone]

SAFETY

Throughout this publication, "DANGER!" and "CAUTION!" blocks are used to alert the mechanic to special
instructions concerning a particular service or operation that might be hazardous if performed incorrectly or
carelessly. PAY CLOSE ATTENTION TO THEM.

DANGER! UNDER THIS HEADING WILL BE FOUND SPECIAL INSTRUCTIONS WHICH, IF NOT COM­PLIED WITH, COULD RESULT IN PERSONAL INJURY OR DEATH.

CAUTION! Under this heading will be found special instructions which, if not complied with, could
result in damage to equipment and/or property.

These "Safety Alerts" alone cannot eliminate the hazards that they signal. Strict compliance with these spe­cial Instructions plus "common sense" are major accident prevention measures.

NOTICE TO USERS OF THIS MANUAL

This SERVICE MANUAL has been written and published by Generac 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 and marketed by Generac. That they have been trained in the recommended
servicing procedures for these products, including the use of common hand tools and any special Generac
tools or tools from other suppliers.

Generac could not possibly know of and advise the service trade of all conceivable procedures by which a
service might be performed and of the possible hazards and/or results of each method. We have not under­taken any such wide evaluation. Therefore, anyone who uses a procedure or tool not recommended by
Generac must first satisfy himself that neither his nor the products safety will be endangered by the service
procedure selected.

All information, illustrations and specifications in this manual are based on the latest product information
available at the time of publication.

When working on these products, remember that the electrical system and engine ignition system are capa­ble of violent and damaging short circuits or severe electrical shocks. If you intend to perform work where
electrical terminals could be grounded or touched, the battery cables should be disconnected at the battery.

Any time the intake or exhaust openings of the engine are exposed during service, they should be covered to
prevent accidental entry of foreign material. Entry of such materials will result in extensive damage when the
engine Is started.

During any maintenance procedure, replacement fasteners must have the same measurements and strength
as the fasteners that were removed. Metric bolts and nuts have numbers that indicate their strength.
Customary bolts use radial lines to indicate strength while most customary nuts do not have strength mark­ings. Mismatched or incorrect fasteners can cause damage, malfunction and possible injury.

REPLACEMENT PARTS

Components on Generac recreational vehicle generators are designed and manufactured to comply with
Recreational Vehicle Industry Association (RVIA) Rules and Regulations to minimize the risk of fire or explo­sion. The use of replacement parts that are not in compliance with such Rules and Regulations could result
in a fire or explosion hazard. When servicing this equipment, It is extremely important that all components be
properly installed and tightened. If Improperly Installed and tightened, sparks could Ignite fuel vapors from
fuel system leaks.

PART TITLE

1 THE AC GENERATOR

2 ENGINE MECHANICAL

3 GASOLINE FUEL SYSTEM

4 GASEOUS FUEL SYSTEM

5 ENGINE OIL & COOLING SYSTEM

6 ENGINE ELECTRICAL SYSTEM

7 TROUBLESHOOTING

8 SPECIFICATIONS & CHARTS

SERIES IMPACT 36 PLUS

TABLE OF CONTENTS

SERVICE

MANUAL

Page 1

PART 1

GENERAL

INFORMATION

COMPUTER

CONTROLLED

VARIABLE
SPEED RV

GENERATORS

Series Impact 36 Plus

SECTION TITLE

1.1 GENERATOR FUNDAMENTALS

1.2 GENERATOR MAJOR COMPONENTS

1.3 OPERATIONAL ANALYSIS

1.4 INSULATION RESISTANCE

1.5 COMPONENTS TESTING

1.6 CONTROL PANEL

1.7 SHEET METAL

NOTES

Section 1.1

GENERATOR FUNDAMENTALS

MAGNETISM

Magnetism can be used to produce electricity and
electricity can be used to produce magnetism.

Much about magnetism cannot be explained by our
present knowledge. However, there are certain pat­terns of behavior that are known. Application of these
behavior patterns has led to the development of gen­erators, motors and numerous other devices that uti­lize magnetism to produce and use electrical energy.

See Figure 1. The space surrounding a magnet is
permeated by magnetic lines of force called "flux".
These lines of force are concentrated at the magnet's
north and south poles. They are directed away from
the magnet at its north pole, travel in a loop and re­enter the magnet at its south pole. The lines of force
form definite patterns which vary in intensity depend­ing on the strength of the magnet. The lines of force
never cross one another. The area surrounding a
magnet in which its lines of force are effective is
called a "magnetic field".

Like poles of a magnet repel each other, while unlike
poles attract each other.

Figure 1. Magnetic Lines of Force

ELECTROMAGNETIC FIELDS

All conductors through which an electric current Is
flowing have a magnetic field surrounding them. This
field is always at right angles to the conductor. If a
compass is placed near the conductor, the compass
needle will move to a right angle with the conductor.
The following rules apply:

• The greater the current flow through the conductor,
the stronger the magnetic field around the conductor.

• The increase in the number of lines of force is
directly proportional to the increase in current flow
and the field is distributed along the full length of
the conductor.

• The direction of the lines of force around a conduc­tor can be determined by what is called the "right
hand rule". To apply this rule, place your right hand
around the conductor with the thumb pointing in the
direction of current flow. The fingers will then be
pointing in the direction of the lines of force.

NOTE: The "right hand rule" is based on the "cur­rent flow" theory which assumes that current
flows from positive to negative. This is opposite
the "electron" theory, which states that current
flows from negative to positive.

Figure 2. The Right Hand Rule

ELECTROMAGNETIC INDUCTION

An electromotive force (EMF) or voltage can be pro­duced in a conductor by moving the conductor so that
it cuts across the lines of force of a magnetic field.

Similarly, if the magnetic lines of force are moved so
that they cut across a conductor, an EMF (voltage)
will be produced in the conductor. This is the basic
principal of the revolving field generator.

Figure 3, below, illustrates a simple revolving field
generator. The permanent magnet (Rotor) is rotated
so that its lines of magnetic force cut across a coil of
wires called a Stator. A voltage is then induced into
the Stator windings. If the Stator circuit is completed
by connecting a load (such as a light bulb), current
will flow in the circuit and the bulb will light.

Figure 3. A Simple Revolving Field Generator

Page 1.1-1

Section 1.1
GENERATOR FUNDAMENTALS

ALTERNATING CURRENT

A simple generator consists of a coil of wires called a
Stator and a magnetic field called a Rotor. As the
Rotor's magnetic field cuts across the Stator coil, a
voltage is induced into the Stator windings. The
amount of induced voltage is equal to the strength of
the magnetic field.

See Figure 4. The current alternates according to the
position of the Rotor's poles in relation to the position
of the Stator. At 0° and again at 180°, no current flow
is produced. At 90° of Rotor rotation, current flow
reaches a maximum positive value. Rotor rotation to
270° brings another maximum flow of current.
However, at 270° the current flow has reversed in
polarity and now flows in the opposite direction.

ELECTRICAL UNITS

AMPERE:
The rate of electron flow in a circuit is represented by

the AMPERE. The ampere is the number of electrons
flowing past a given point at a given time. One
AMPERE is equal to just slightly more than six thou­sand million billion electrons per second.

With alternating current (AC), the electrons flow first
in one direction, then reverse and move in the oppo­site direction. They will repeat this cycle at regular
intervals. A wave diagram, called a "sine wave"
shows that current goes from zero to maximum posi­tive value, then reverses and goes from zero to maxi-

mum negative value. Two reversals of current flow is
called a cycle. The number of cycles per second is
called frequency and is usually stated in "Hertz".

Figure 5. Alternating Current Sine Wave

VOLT:
The VOLT is the unit used to measure electrical

PRESSURE, or the difference in electrical potential
that causes electrons :o flow. Very few electrons will
flow when voltage is weak. More electrons will flow as
voltage becomes stronger. VOLTAGE may be consid­ered to be a state of unbalance and current flow as
an attempt to regain balance. One volt is the amount
of EMF that will cause a current of 1 ampere to flow
through 1 ohm of resistance.

Page 1.1-2

Figure 4. Operation of a Simple Generator

Section 1.1

GENERATOR FUNDAMENTALS

Figure 6. Electrical Units

OHM:
The OHM is the unit of RESISTANCE. In every circuit

there is a natural resistance or opposition to the flow
of electrons. When an EMF is applied to a complete
circuit, the electrons are forced to flow in a single
direction rather than their free or orbiting pattern. The
resistance of a conductor depends on (a) its physical
makeup, (b) its cross-sectional area, (c) its length,
and (d) its temperature. As the conductor's tempera­ture increases, its resistance increases in direct pro­portion. One (1) ohm of resistance will permit one (1)
ampere of current to flow when one (1) volt of electro­motive force (EMF) is applied.

OHM'S LAW

A definite and exact relationship exists between
VOLTS, OHMS and AMPERES. The value of one can
be calculated when the value of the other two are
known. Ohm's Law states that in any circuit the current
will increase when voltage increases but resistance
remains the same, and current will decrease when
resistance Increases and voltage remains the same.

Figure 7.

If AMPERES is unknown while VOLTS and OHMS
are known, use the following formula:

AMPERES =

VOLTS

OHMS

If VOLTS is unknown while AMPERES and OHMS
are known, use the following formula:

VOLTS = AMPERES x OHMS

If OHMS is unknown but VOLTS and AMPERES are
known, use the following:

OHMS

=

VOLTS

AMPERES

REACTANCE IN AC CIRCUITS

GENERAL:
When direct current (DC) is flowing, the only opposi-

tion to current flow that must be considered is resis­tance (ohms). This is also true of alternating current
(AC) when only resistance type loads such as heating
and lamp elements are on the circuit. In such a case,
current will be in phase with voltage- that is, the cur­rent sine wave will coincide in time with the voltage
sine wave.

However, two factors in AC circuits called INDUC­TIVE and CAPACITIVE REACTANCE will prevent the
voltage and current sine waves from being in phase.

INDUCTIVE REACTANCE:
This condition exists when current lags behind volt-

age (Figure 8). As current flows in a circuit, magnetic
lines of force are created at right angles to the con­ductor. The continuous changes in current value
(from positive to negative) cause these magnetic lines
to collapse and build up continuously.

The magnetic field around the conductor induces
electromotive forces that cause current to keep on
flowing while voltage drops. The result is a condition
in which voltage leads current. When a conductor is
formed into a coil, the magnetic lines of force are con­centrated in the center of the coil. This increased den­sity causes an increase in magnetically Induced EMF
without increasing current Thus, coils cause inductive
reactance.

Inductive reactance can also be caused by placing an
induction motor on the circuit which utilizes the cur­rent's magnetic field for excitation.

Figure 8. Inductive Reactance

Page 1.1-3

Section 1.1
GENERATOR FUNDAMENTALS

CAPACITIVE REACTANCE:
This condition occurs when current leads voltage

(Figure 9). It might be thought of as the ability to oppose
change in voltage. Capacitance exists in a circuit when
certain devices are ~a) capable of storing electrical
charges as voltage increases and (b) discharging these
stored charges when the voltage decreases.

Figure 9. Capacitive Reactance

WHAT IS AN "IMPACT PLUS" UNIT?:
The Impact Plus is a computer controlled generator

that uses an inverter to create a superior sine wave
and maintain a steady frequency. These units are dif­ferent from conventional generators in that the perfor­mance of the engine and AC generator are more
accurately matched over a wide range of power
needs. The Impact Plus computer controlled genera­tor provides greater efficiency of both the engine and
the generator while maintaining electrical output with­in an acceptable voltage range. The frequency is con-

trolled by the inverter and is maintained at a steady
60 Hz signal throughout the load range.

Computer controlled generator units have the ability
to operate the engine over a wide range of speeds,
while conventional generators will deliver correct AC
frequency and voltage only at a fixed rpm.

Unlike conventional AC generators, the Impact Plus
unit can match engine speed to load requirements.
This provides several advantages, as follows:

• Smaller engines can be used to produce more
power than on a conventional generator, since it
can be allowed to run at a higher speed.

• When the load is reduced, the engine can run at
slower than the usual speeds. This improves fuel
economy and reduces engine noise.

• The Impact Plus unit can be operated closer to its
peak power point at all times, because output volt­age and current are functions of engine speed. This
allows for a much more compact generator design.

IMPACT PLUS SYSTEM OVERVIEW:
Figure 10 is a block diagram of the Impact Plus sys-

tem. The major elements of the system are represent­ed in the diagram. Operation of the system may be
described briefly as follows:

1. The engine is directly coupled to a permanent magnet type
Rotor, so the Rotor runs at the same speed as the engine.

2. As the Rotor turns, its magnetic field cuts across the Stator
windings to induce a voltage into the Stator.

Page 1.1-4

Figure 10. Block Diagram of the Impact 36 Plus System

Section 1.1

GENERATOR FUNDAMENTALS

3. When the generator circuit breaker is turned to the “ON” position,
AC voltage is delivered to the Full Bridge Rectifier. The AC volt­age is rectified to DC and thus becomes DC Link voltage.

4. AC voltage from the stator PS1/PS2 is delivered to the inverter.
This is used as the power supply for the inverter circuit board.

5. AC voltage from the stator TIM1/TIM2 is delivered to the system
controller. This is used for engine speed sensing.

6. The system controller sends signals to the inverter for inverter
operation.

7. The system controller senses load voltage and signals stepper
motor operation to achieve required engine speed for correct
voltage output.

WHY VARIABLE SPEED CONTROL?

Most electrical loads will operate satisfactorily only
within a relatively small voltage band. In order to pro­vide useful voltage at larger load currents, it is neces­sary to increase engine speed.

In conventional AC generators, some form of voltage
regulation is needed to provide correct voltage in the
full range of load current. This is often accomplished
by regulating excitation current to the Rotor (field)
which then regulates the strength of the Rotor's mag­netic field. The voltage induced into the Stator wind­ings is proportional to the strength of the Rotor's mag­netic field.

The Impact Plus computer controlled generator uses
a Rotor having a fixed and permanent magnetic field.
The strength of this magnetic field is fixed and cannot
be regulated.

The output voltage on Impact Plus computer con­trolled generators tends to droop with increasing elec­trical loads. The SYSTEM CONTROLLER maintains
a constant AC output voltage by increasing engine
and Rotor speed as the load current increases, to off­set this inherent voltage droop.

Page 1.1-5

Section 1.1
GENERATOR FUNDAMENTALS

Page 1.1-6

Section 1.2

MAJOR GENERATOR COMPONENTS

INTRODUCTION

Major components of the generator proper are shown
in Figure 1, below. External sheet metal and other
unrelated components are omitted from the drawing
for clarity. These parts are:

Item Description

1 Upper Fan Housing
2 Upper Cooling Fan
3 Permanent Magnet Rotor
4 Rotor Hub
5 Stator Retaining Ring
6 Stator Assembly
7 Stator Adapter
8 Engine
9 Lower Fan & Flywheel

10 Stepper Motor

Figure 1. Exploded View of Generator Proper

UPPER FAN HOUSING

As its name implies, this component houses and
shields the upper cooling fan. See Figure 1, Item 1.

UPPER COOLING FAN

The Cooling Fan draws air into the generator through
slots in the Upper Fan Housing. It is fastened to and
rotates with the Permanent Magnet Rotor.

PERMANENT MAGNET ROTOR

Sixteen permanent magnets have been affixed to the
Rotor. A starter ring gear is welded to the Rotor. The
Rotor and Hub are balanced at the factory as an
assembly and must be replaced as an assembly.

NOTE: The hub MUST be properly aligned during
reassembly. The mounting bolt, housing opening
and magnet must be properly aligned. In addition,
match marks between the Hub and Rotor must be'
aligned as indicated by an "ALIGN MARKS FOR
BALANCE" decal. During assembly, use care to
avoid damage to the Ignition Sensor.

DANGER! The permanent magnet rotor pro­duces an extremely strong magnetic force.
Use care during installation to avoid pinched
fingers.

Figure 2 Permanent Magnet Rotor Assembly

Page 1.2-1

Section 1.2
MAJOR GENERATOR COMPONENTS

ROTOR HUB

See Figure 2 on previous page. The Rotor Hub is bal­anced with the Rotor and must be replaced with the
Rotor as an assembly. Part of the engine ignition sys­tem is pressed onto the Hub and can be replaced
only as part of the Rotor and Hub assembly.

STATOR RETAINING RING

The Stator Retaining Ring is made of die-cast alu­minum. Four hex head capscrews with lockwashers
pass through holes in the Retaining Ring, to retain
the Stator Assembly to the Stator Adapter (Item 7,
Figure 1).

STATOR ASSEMBLY

The 2-phase Stator is made up of six (6) windings,
with leads brought out as shown in figure 4. Figure 5
is a schematic representation of each stator winding.
Note that there are two (2) power phase windings
(Leads AC1, AC2, SL1 and SL2 ); a timing winding
(Leads TIM1 and TIM2); a power supply winding
(Leads PSI, PS2); and a dual battery charge winding
(Leads 55, 66, 77).

STATOR ADAPTER

The Adapter is retained to the engine by means of
four hex head capscrews. The Stator is retained to
the Stator Adapter and is "sandwiched" between the
Adapter and the Stator Retaining Ring.

LOWER FAN & FLYWHEEL

The Lower Fan and Flywheel are retained to the
engine PTO shaft by means of a conical washer and
an M16-1.50 hex nut. When assembling, tighten the
flywheel nut to 75 foot-pounds.

ENGINE

The engine is a single cylinder, 220 cc, overhead
valve type manufactured by Generac® Power
Systems, Inc.

STEPPER MOTOR

The Stepper Motor (Figure 3) consists of a stepper
motor along with a gear and cam arrangement which
allows motor movement to change the engine carbu­retor throttle setting. The Motor is controlled by output
signals from the Computer Control Circuit Board,
which calculates the number of steps the stepper
needs to take and generates the required signals to
the Motor. The circuit board signals the Motor to actu­ate in response to changes in AC output voltage.
Thus, in response to decreasing AC output voltages,
the Motor will increase the throttle setting and engine
speed will increase. Conversely, Increasing AC out­put voltages will cause the Motor to decrease throttle
setting and engine speed will decrease.

Figure 3. The Stepper Motor

Figure 4. Stator Pictorial View

Page 1.2-2

Section 1.2

MAJOR GENERATOR COMPONENTS

Figure 5. Schematic- Stator Windings

Page 1.2-3

Section 1.2
MAJOR GENERATOR COMPONENTS

Page 1.2-4

Section 1.3

OPERATIONAL ANALYSIS

GENERAL

Figure 1, below, is a block diagram of the Impact Plus
computer controlled RV generator. The diagram is
Intended only for the purpose of illustrating generator
operation. Refer to the actual wiring diagram for
wiring interconnections.

OPERATIONAL DESCRIPTION

1. The Impact Plus is a computer controlled generator that uses
an inverter to create a superior sine wave and maintain a
steady frequency of 60 Hz. The PERMANENT MAGNET
ROTOR is directly coupled to the ENGINE and rotates at the
same speed as the engine.

2. As the ROTOR turns, its magnetic field cuts across a number
of STATOR windings, to induce a voltage into those windings.
A voltage is induced into the following STATOR windings:

a. Phase 1 and 2 of the STATOR POWER WIND-

INGS (output leads AC1-AC2 and SL1-SL2).

b. The STATOR POWER SUPPLY WINDING with

output leads PS1-PS2.

c. The STATOR TIMING WINDING (output leads

TIM1-TIM2).

d. STATOR BATTERY CHARGE WINDING with

output leads 55, 66 and 77.

3. STATOR BATTERY CHARGE WINDING output is delivered to
the unit battery via a BATTERY CHARGE RECTIFIER (BCR)
and a 1 OHM, 50 WATT RESISTOR. The circuit is completed
through the battery to frame ground and back to the BATTERY
CHARGE WINDING via Wire 55.

4. Stator timing winding output is delivered to the A6060 circuit
board. The timing winding output is used to determine engine rpm.

5.The stator power supply winding output is delivered to the
inverter. This is the power supply for operation of the inverter.

6. Stator power winding output (phase 1 and 2) is delivered to two
separate bridge rectifiers, where it is rectified to DC. This
becomes the DC link voltage and is delivered to the inverter.

Page 1.3-1

Figure 1. Block Diagram- A Generator System

Section 1.3
OPERATIONAL ANALYSIS

OPERATIONAL DESCRIPTION (CONTINUED)

7. The A6060 circuit board controls all functions of the generator,
i.e.:

a.Engine DC control system
b.Stepper motor operation

(1) If voltage is low, the board will signal a

STEPPER MOTOR to change engine throt­tle setting and increase speed until the
desired voltage level is reached.

(2) If voltage goes high, the board will signal

the STEPPER MOTOR to reduce engine
throttle setting until the desired voltage level
is obtained.

c.Output signals for operation of inverter.

Page 1.3-2

Section 1.4

INSULATION RESISTANCE

DIRT AND MOISTURE

If moisture is permitted to remain in contact with the
generator Stator windings, some of it will be retained
in voids and cracks of the winding insulation. This can
eventually cause a reduction in insulation resistance
and generator output may be affected.

Winding insulation in Generac generators is moisture
resistant. However, prolonged exposure to water,
high humidity, salt air, etc., will gradually reduce the
resistance of winding insulation.

Dirt can make the problem even worse, since it tends
to hold moisture into contact with the windings. Salt,
as from sea air, can also worsen the problem, since
salt tends to absorb moisture from the air. When salt
and moisture combine, they make a good electrical
conductor.

Because of the detrimental effects of water, dirt and
salt, the generator should be kept as dry and as clean
as possible. Stator windings should be tested periodi­cally using a Hi-Pot tester or a Megohmmeter. If insu­lation resistance is low, drying of the unit may be nec­essary. If resistance is still low after drying, the defec­tive Stator should be replaced.

INSULATION RESISTANCE TESTERS

One kind of insulation resistance tester is shown in
Figure 1, below. Other types are commercially avail­able. The type shown has a "Breakdown" lamp which
turns on to indicate an insulation breakdown during
the test.

One common type of tester is the "Megohmmeter"
which measures resistance in "Megohms".

Figure 1. One Kind of Hi-Pot Tester

CAUTION! When using a Megohmmeter or
any other tester, be sure to follow the manu­facturer's instructions carefully. All Stator
leads must be isolated from other compo­nents, especially circuit boards, before per­forming tests. The high voltages used in test­ing insulation resistance will damage elec­tronic components.

STATOR LEADS

The following leads are brought out of the Stator and
connected to various components in the unit:

WIRE# COLOR CONNECTS TO
AC1 Grey CB1A
AC2 Yellow BR1
SL1 Orange CB1B
SL2 Brown BR3
TIM1 Orange A6060 Circuit Board
TIM2 Grey A6060 Circuit Board
PS1 Red J1
PS2 Black J1
77 Brown Battery Charge Rectifier BCR
66 Brown Battery Charge Rectifier BCR
55 Black Grounding Terminal

Figure 2. Stator Leads

PREPARATION FOR TESTS

See Stator leads CHART above. Disconnect and iso­late all Stator leads. ALL STATOR LEADS MUST BE
DISCONNECTED AND ISOLATED BEFORE START­ING THE TESTS.

Page 1.4-1

Section 1.4
INSULATION RESISTANCE

TEST ALL STATOR WINDINGS TO GROUND

Connect the ends of all Stator leads together. Make
sure none of the leads are touching any terminal or
any part of the generator.

Connect one Tester probe to the junction of all Stator
leads; the other Tester probe to a clean frame ground
on the Stator. Apply a voltage of 1000 volts for about
1 second.

Follow the tester manufacturer's instructions carefully.
Some "Hi-Pot" testers are equipped with a
"Breakdown" light which will turn ON to indicate an
insulation breakdown.

A "Megger" (Megohmmeter) will indicate the
"megohms" of resistance. Normal Stator winding
insulation resistance is on the order of "millions of
ohms" or "megohms". The MINIMUM acceptable
insulation resistance reading for Stators can be calcu­lated using the following formula.

MINIMUM INSULATION

=

GENERATOR RATED VOLTS

+1

RESISTANCE

1000

(in “megohms”)

EXAMPLE: Generator rated voltage Is "120 VAC".
Divide 120 by 7000 to obtain "0.12". Add "7" to
obtain "1.12". Minimum Insulation resistance for
the unit Is "7.12 megohms".

TEST FOR SHORTS BETWEEN WINDINGS

Figure 2 on the previous page shows the Stator leads
that are brought out of the Stator. Figure 3 is a
schematic representation of the eight (8) Stator wind­ings. To test for shorts between windings, proceed as
follows:

1. Make sure all Stator output leads are isolated from each other
and from the frame.

2. POWER PHASE TO TIMING WINDINGS:- Connect one tester
probe to Stator lead AC1, the other test probe to Stator lead
TIM1. Apply a voltage of 1000 volts. The Tester will indicate a
breakdown if the windings are shorted together. Repeat again
with stator lead SL1.

3. POWER PHASE TO POWER SUPPLY WINDINGS: Connect
one tester probe to Stator lead AC1, the other tester probe to
Stator lead PS1. Apply 1000 volts. If a breakdown Is indicated,
the windings are shorted together. Repeat again with stator lead
SL1.

4. POWER PHASE TO BATTERY CHARGE WINDINGS:Connect
one tester probe to Stator Lead AC1, the other probe to Stator
lead No. 55. Apply 1000 volts. If breakdown Is indicated, the
windings are shorted together. Repeat again with stator lead
SL1.

5. TIMING TO POWER SUPPLY WINDING:- Connect one tester
probe to Stator lead No. TM1, the other test probe to Stator
lead No. PS1. Apply 1000 volts. If breakdown is indicated, the
windings are shorted together.

6. TIMING TO BATTERY CHARGE WINDING:- Connect one test
probe to Stator lead No. TIM1, the other test probe to Stator
lead No. 55. Apply 1000 volts. If breakdown is indicated the
windings are shorted together.

7. POWER SUPPLY TO BATTERY CHARGE WINDING:Connect
one test probe to Stator lead No. PS1, the other probe to Stator
lead No. 55. Apply 1000 volts. If breakdown is indicated, the
windings are shorted together.

RESULTS OF TESTS

1. If testing indicates that Stator windings are shorted to ground,
the Stator should be cleaned and dried. The insulation resis­tance tests should then be repeated. If, after cleaning and dry­ing, the Stator again fails the test, replace the Stator assembly.

2. If testing indicates that a short between windings exists,
clean and dry the Stator. Then, repeat the tests. If Stator
fails a second test (after cleaning and drying), replace the
Stator assembly.

CLEANING THE GENERATOR

GENERAL:
If testing indicates that the insulation resistance is

below a safe value, the winding should be cleaned.
Proper cleaning can be accomplished only while the
generator is disassembled. The cleaning method
used should be determined by the type of dirt to be
removed. Be sure to dry the unit after it has been
cleaned. An electric motor repair shop may be able to
assist with cleaning. Such shops are often experi­enced in special problems (sea coast, marine, wet­land applications, etc.).

Page 1.4-2

Section 1.4

INSULATION RESISTANCE

Figure 3. Schematic- Stator Windings

USING SOLVENTS FOR CLEANING:
A solvent is generally required when dirt contains oil

or grease. Only petroleum distillates should be used
to clean electrical components. Recommended are
safety type petroleum solvents having a flash point
greater than 100° F. (38° C.).

Use a soft brush or cloth to apply the solvent. Use
care to avoid damaging magnet wire or winding insu­lation. After cleaning, dry all components thoroughly
with moisture-free, low pressure compressed air.

DANGER! DO NOT WORK WITH SOLVENTS
IN ANY ENCLOSED AREA. ALWAYS PRO­VIDE ADEQUATE VENTILATION. FIRE,
EXPLOSION OR OTHER HEALTH HAZARDS
MAY EXIST UNLESS ADEQUATE VENTILA­TION IS PROVIDED. WEAR EYE PROTEC­TION. WEAR RUBBER GLOVES TO PROTECT
THE HANDS.

CAUTION! Some generators use epoxy or
polyester base winding varnishes. Use sol­vents that do not at tack such materials.

DRYING THE GENERATOR

GENERAL:
If testing indicates that the insulation resistance of a

winding Is below a safe value, the winding should be
dried before operating the unit Some recommended
drying methods include (a) heating units and (b)
forced air.

HEATING UNITS:
If drying is needed, the generator can be enclosed in

a covering. Heating units can then be installed to
raise the temperature about 15°-18° F. (8°-10° C.)
above ambient.

FORCED AIR:
Portable forced air heaters can be used to dry the

generator. Direct the heated air into the generator's
air intake openings. Run the unit at no-load. Air tem­perature at the point of entry into the generator should
not exceed 150° F. (66° C.).

Page 1.4-3

Section 1.4
INSULATION RESISTANCE

Page 1.4-4

Section 1.5

COMPONENTS TESTING

INTRODUCTION

Problems that occur In the computer-controlled RV
generator generally involve the following systems or
components:

1. The engine.

2. The Speed Control System.

3. The AC Generator.

4. Battery Charge Circuit.

5. A6060 Circuit Board.

6. Wiring Harness and Front Panel.
This Section will discuss test procedures for the fol-

lowing components. Also see Part 8 of this Manual,
"TROUBLESHOOTING".

1. The AC Generator (Stator).

2. Battery Charge Circuit.

3. A6060 Circuit Board.

STATOR ASSEMBLY

GENERAL:
For additional information on the Stator, refer to the

following:

1. "Stator Assembly" on Page 1.2-2.

2. Section 1.4, "INSULATION RESISTANCE".
SYMPTOMS OF STATOR FAILURE:

If the engine starts but the Stepper Motor does not
move, and shutdown occurs after several seconds,
look for broken or shorted timing windings (Wires
TIM1 and TIM2).

TESTING THE STATOR WITH A VOM:
A Volt-Ohm-Milliammeter (VOM) can be used to test

the Stator windings for the following faults:

• An open circuit condition.

• A "short-to-ground" condition.

• A short circuit between windings.

NOTE: The resistance of Stator windings Is very
low. Some meters will not read such a low resis­tance and will simply Indicate "continuity"
Recommended Is a high quality, digital type meter
capable of reading very low resistances.

TESTING POWER PHASE WINDINGS:
A.Refer to Figures 1 and 2 on this page and the next. To test the

Power Phase windings for an open circuit condition, proceed
as follows:

1.Disconnect the following wires:
a. Lead "AC1" (Grey) at CB1A.
b. Lead "AC2" (Yellow) at BR1.
c. Lead "SL1 " (Orange) at CB1B.
d. Lead "SL2" (Brown) at BR3.

2.Make sure all of the disconnected leads are iso-

lated from each other and are not touching the
frame during the test.

3.Set a VOM to its "Rx1" scale and zero the meter.

4.Connect one test lead to AC1 and one test lead

to AC2. Note the resistance reading.

5. Connect one test lead to SL1 and one test lead

to SL2. Note the resistance reading.

NOMINAL RESISTANCE- POWER PHASE WINDINGS

0.414 to 0.465 ohm

Figure 1. Stator Leads

B.To test the Power Phase windings for a "short-to-ground" con-

dition, proceed as follows:

1.Make sure all leads are Isolated from each other

and are not touching the frame.

2. Set a VOM to its "Rx10,000" or "Rx1K" scale

and zero the meter.

3. Connect one VOM test lead to the terminal end

of Stator Lead "AC1”, the other test lead to a

clean frame ground on the Stator.
a. The meter should read "infinity".
b. Any reading other than "infinity" indicates a

"short-to-ground" condition.

c. Repeat #3 again using Stator Lead “SL1.”

Page 1.5-1

Section 1.5
COMPONENTS TESTING

STATOR ASSEMBLY (CONTINUED)

Figure 2. Schematic- Stator Windings

TESTING POWER SUPPLY WINDINGS:
A.To test the Power Supply winding for an open circuit condition,

proceed as follows:

1.Disconnect the 2-wire power supply from the
generator. See Figure 3.

2.Set a VOM to its "Rx1" scale and zero the meter.

3. Connect one VOM test lead to Lead PS1- Red,
the other test lead to Lead PS2 - Black. The
meter should indicate the resistance of the
Power Supply winding.

NOMINAL RESISTANCE

POWER SUPPLY WINDING

0.206-0.227 ohm

B.To test the Power Supply winding for a "short-to-ground" condi-

tion, proceed as follows:

1. Set the VOM to its "Rx10,000" or "Rx1 K" scale
and zero the meter.

2.Connect one VOM test lead to Lead PS1 - Red.
Connect the other test lead to a clean frame
ground on the Stator. The meter should read
"infinity.”

NOTE: Any reading other than °Infinity" Indicates
the winding Is shorted to ground. If winding is
open or shorted, the Stator should be replaced.

TESTING THE TIMING WINDING:
A.To test the Stator Timing winding for an open circuit condition,

proceed as follows:

1. Disconnect the 2-pin connector from "J5" of the
A6060 circuit board. See Figure 3.

a. Stator lead TIM1 (Orange) connects to Pin

1 of the “J5” connector.

b. Stator lead TIM2 (Gray) connects to Pin 2

of the “J5” connector.

2.Set a VOM to its "Rx1" scale and zero the
meter.

3.Connect one VOM test lead to Pin 1 (Lead TIM1
Orange); connect the. other test lead to Pin 2
(Lead TIM2- Gray). The meter should Indicate
the Stator Timing winding resistance.

NOMINAL RESISTANCE

STATOR TIMING WINDING

0.102-0.116 ohm

B. To test the Timing winding for a "short-to-ground" condition,

proceed as follows:

1. Set the VOM to its "Rx10,000" or "Rx1 K" scale
and zero the meter.

2.Connect one VOM test lead to Pin 1 of the 2-pin
connector (Lead TIM1-Orange).

3.Connect the other test lead to a clean frame
ground on the Stator. The meter should read
"infinity". Any reading other than "infinity" indi­cates the Timing winding is shorted to ground.

SHORT CIRCUIT BETWEEN WINDINGS:
To test for a short circuit between windings, proceed

as follows:

1. Set a VOM to its "Rx10,000" or "Rx1K" scale
and zero the meter.

2. Connect one meter test lead to Stator lead PSi
(Red).

3. Connect the remaining test lead to Stator lead
AC1 (Grey). The meter should read "infinity".
Any reading other than "infinity" indicates a
shorted condition and the Stator should be
replaced.

4.Connect one VOM test lead to Stator lead AC1,
the other test lead to Stator lead 77. The VOM
should read "infinity".

5.Connect one VOM test lead to Stator lead AC1,
the other test lead to Stator lead TIM1. The
meter should read "infinity".

6. Connect one test lead to Stator lead PSI, the
other to Stator lead TIM1. "Infinity" should be
indicated.

Page 1.5-2

Section 1.5

COMPONENTS TESTING

7. Connect one test lead to Stator lead PS1, the
other to Stator lead 77. The VOM should read
"infinity".

8.Connect one VOM test lead to Stator lead TIM1,
the other test lead to Stator lead 77. "Infinity"
should be Indicated.

TESTING THE BATTERY CHARGE CIRCUIT

GENERAL:
The Stator is equipped with dual battery charge wind-

ings. These windings deliver an AC output to a
Battery Charge Rectifier (BCR) which rectifies it
(changes it to direct current or DC). The direct current
is delivered to the unit battery, to maintain the battery
in a charged state while the unit is running.

Figure 3. Battery Charge Windings and Rectifier

SYMPTOMS OF CIRCUIT FAILURE:
It is difficult to determine if the battery charge circuit is

operating without testing for correct voltage. If you
suspect the battery charge circuit Is defective, the fol­lowing symptoms will usually point to a cause of the
problem. See Figure 4.

1. If no AC voltage can be measured across Stator connections at
the Battery Charge Rectifier (BCR), an open circuit condition
probably exists in Wire 66 (Brown), or Wire 77 (Brown).

2. If AC voltage (s available to the Wire 66 and 77 terminals at the
battery Charge Rectifier, but no voltage or a low voltage is mea­sured between the BCR's Wire 55 terminal and ground, the
Battery Charge Rectifier (BCR) is defective.

Figure 4. Battery Charge Circuit

TESTING THE BATTERY CHARGE CIRCUIT:
Test the Battery Charge winding as follows:

1. Disconnect Wire 77 at the Battery Charge Rectifier (BCR).

2. Disconnect Stator output Wire 66 at the Battery Charge
Rectifier (BCR).

3. Disconnect Wire 55.

4. Set a VOM to its "Rx1 " scale and zero the meter.

5. Connect the VOM test leads across Wires 77 and 55, then
across Wires 66 and 55. Note the resistance reading in both
cases. Replace Stator Assembly, if defective.

BATTERY CHARGE WINDING RESISTANCE
ACROSS WIRES 66 TO 55 = 0.095-0.108 Ohm
ACROSS WIRES 77 TO 55 = 0.095-0.108 Ohm

6. Use a VOM to measure AC voltage at the Wires 66 and 77 ter­minals of the Battery Charge Rectifier, with the unit running. If
no AC voltage is measured, an open circuit exists in the wire
66 or 77 circuit.

7. With engine running, use a VOM to check for DC voltage
between the Battery Charge Rectifiers Wire 55 and frame
ground. If AC voltage was present in step 6, but DC voltage is
NOT present in this step, the Battery Charge Rectifier (BCR) is
defective.

Page 1.5-3

Section 1.5
COMPONENTS TESTING

Page 1.5-4

Section 1.6

CONTROL PANEL

CONSTRUCTION

The panel is constructed of sheet metal and includes
a panel box, a panel back cover and a front control
panel. The panel box is retained to an engine-genera­tor divider plate by five M5 screws. Removal of these
screws will permit the panel to be removed from the
divider plate and set out of the way with connecting
wires still attached. This will allow access to compo­nents housed in the control panel.

COMPONENTS

A heat sink bracket is attached to the engine-genera­tor divider plate, for attachment of a heat sink to
which four diode assemblies are mounted. See Items
26 and 31 in the Exploded View of Control Panel.
Other components are also shown in the Exploded
View. Many of these components are part of the
"ENGINE ELECTRICAL SYSTEM" (Part 6 of this
manual).

Page 1.6-1

Figure 1. Exploded View of Control Panel

ITEM QTY. DESCRIPTION

1 9 M50.8 x 12MM PHILLIPS PAN HD.MACH. SCR.
2 1 BOX, CONTROL TOP
3 1 BOX, CONTROL PANEL
4 1 #1032 x 1" PHILLIPS PAN HD. MACH. SCR.
5 1 #1032 HEX NUT
6 8 TAPTITE M5.8 x 10MM
7 1 SNAP BUSHING
8 1 CONNECTOR
10 1 CIRCUIT BREAKER,10A.
11 2 LOCK WASHERM6
12 1 IGNITION MODULE
13 10 LOCK WASHERM5
14 2 POP RIVET.156D
15 2 HEX NUT M6
16 1 ASSEMBLY, COIL
17 2 SPACER, IGNITION COIL MOUNT
18 4 M4 FLAT WASHER
19 8 M5 FLAT WASHER
20 1 CONTROL PANEL, FRONT
21 1 SNAP BUSHING
22 1 SWITCH, SPDT ROCKER
23 1 SWITCH, SPST MOM ROCKER
24 1 FUSE, 15A. AGC
25 1 FUSE HOLDER
26 1 EXTRUSION, CONTROLLER
27 1 RECTIFIER, BATTERY CHARGE
28 4 LOCK WASHERM4
30 1 PANEL DECAL
31 4 DIODE, DUAL 30A
32 1 ASSEMBLY, PCB A6060
33 2 PHMS M30.5 x 10
34 2 LOCK WASHERM3
35 1 RESISTOR, POWER 1 OHM

ITEM QTY. DESCRIPTION

36 2 BUS BAR, OUTER
37 4 TAPTITE M61 x 10MM
38 1 BRACKET, HEAT SINKPCB
40 2 HEX NUT M5
41 1 TERMINAL BLOCK
43 4 BUS BAR, INNER
44 1 GROUND WIRE
45 1 CUSTOMER WIRE HARNESS
46 1 REMOTE PANEL HARNESS
47 1 SNAP BUSHING
48 2 CLAMP, CONTROL PANEL HARNESS
49 1 HARNESS, CONTROL PANEL (NOT SHOWNFOR CLARITY)
50 4 #632 x 1/4" PHILLIPS ROUND HD. MACH. SCREW
51 5 RUBBER UCHANNEL
52 4 M40.7 x 10MM HEX HEAD CAPSCREW
53 1 HOUR METER
54 2 #440 x 3/8" LG ROUND HD
55 2 #4 LOCKWASHER
56 2 #440 HEX NUT
57 4 PPHMS 1032 x 3/8" LG
58 1 BUS BAR, CENTER
59 1 BLACK TIE WRAP, 7" LG
60 4 SHAKEPROOF EXT. #10
61 1 INVERTER ASSEMBLY
62 1 WIRE HARNESS, 7 CONDUCTOR
63 1 WIRE HARNESS, 2 CONDUCTOR
64 1 WIRE HARNESSHEATSINK TO PCBI
65 1 HARNESSPCBI TO PANEL
66 1 HARNESS - HEATSINK TO TERM. BLOCK
67 1 TERMINAL BLOCK, 4 POSITION
68 2 POP RIVET
69 2 M3.05 NUT

Section 1.6
CONTROL PANEL

Page 1.6-2

Section 1.7

SHEET METAL

See "Exploded View of Sheet Metal" on next page. A
DIVIDER PLATE (Item 1) separates the AC generator
components from the engine. The engine Itself is
enclosed by a BASE HOUSING WRAPPER (Item 4),
a FRAME (Item 24), and a BELLY PAN (Item 23).
These components are sealed by means of rubber
SEALS (Items 3), to prevent

The LOWER FAN attaches to the engine shaft and is
enclosed in a LOWER FAN HOUSING (Item 19). Air
is drawn Into the enclosed area around the engine
and forced out of the LOWER FAN HOUSING.

Removal of sheet metal will be necessary for many
repairs and for replacement of most parts.

Page 1.7-1

GENERAL

Impact Plus Generator

Section 1.7
SHEET METAL

Page 1.7-2

EXPLODED VIEW OF SHEET METAL (GASOLINE UNITS)