Miller MSW-41 User manual

Processes
Description
Resistance Spot
Welding
TM-716D 2011−03
Eff. w/Style Number HD-6
MSW-41, MSW-41T, MSW-42, MSW-42T,
LMSW-52, And LMSW-52T
Portable Resistance Spotwelders
Visit our website at
www.MillerWelds.com
File: Resistance
Spot Welding

TABLE OF CONTENTS
SECTION 1 −SAFETY PRECAUTIONS FOR SERVICING 1.........................................
1.1 Symbol Usage 1........................................................................
1.2 Servicing Hazards 1....................................................................
1.3 California Proposition 65 Warnings 2.......................................................
1.4 EMF Information 2......................................................................
SECTION 2 −−INTRODUCTION 3................................................................
2-1. Specifications 3........................................................................
SECTION 3 −INSTALLATION 3..................................................................
3-1. Installing Or Dressing Tips 3..............................................................
3-2. Installing Or Cleaning Tongs 5............................................................
3-3. Adjusting Tong And Hand Lever Pressure 6.................................................
3-4. Installing Handle 7......................................................................
3-5. Mounting Control Box 8..................................................................
3-6. Connecting Input Power (T Models) 8......................................................
3-7. Connecting Input Power (Non-T Models) 9..................................................
SECTION 4 −OPERATION 10....................................................................
4-1. Controls (T Models) 10...................................................................
4-2. Controls (Non-T Models) 10...............................................................
SECTION 5 −THEORY OF OPERATION 11........................................................
SECTION 6 −TROUBLESHOOTING 13............................................................
6-1. Troubleshooting Table 13.................................................................
6-2. Troubleshooting Circuit Diagram For 1.5 KVA (110 Or 220V) And 2.5 KVA
(220V) Models 15........................................................................
6-3. Troubleshooting Circuit Diagram For 1.5 KVA, 110 Volts Model 16...............................
6-4. Troubleshooting Circuit Diagram For 1.5 And 2.5 KVA, 220 Volts Models 17.......................
6-5. Waveforms For Sections 6-2, 6-3 And 6-4 18.................................................
SECTION 7 −MAINTENANCE 19.................................................................
7-1. Routine Maintenance 19..................................................................
7-2. Overload Protection For 220 Volts Model 19..................................................
SECTION 8 −ELECTRICAL DIAGRAMS 20........................................................
SECTION 9 −PARTS LIST 24.....................................................................

TM-716 Page 1
MSW And LMSW Series
SECTION 1 −SAFETY PRECAUTIONS FOR SERVICING
Protect yourself and others from injury — read and follow these precautions.
1.1 Symbol Usage
OM-716H - 2011−12, safety_spottm 2010−03
DANGER! −Indicates a hazardous situation which, if
not avoided, will result in death or serious injury. The
possible hazards are shown in the adjoining symbols
or explained in the text.
Indicates a hazardous situation which, if not avoided,
could result in death or serious injury. The possible
hazards are shown in the adjoining symbols or ex-
plained in the text.
NOTICE −Indicates statements not related to personal injury.
.Indicates special instructions.
This group of symbols means Warning! Watch Out! ELECTRIC
SHOCK, MOVING PARTS, and HOT PARTS hazards. Consult sym-
bols and related instructions below for necessary actions to avoid
the hazards.
1.2 Servicing Hazards
The symbols shown below are used throughout this manual
to call attention to and identify possible hazards. When you
see the symbol, watch out, and follow the related instruc-
tions to avoid the hazard.
Only qualified persons should service, test, maintain, and
repair this unit.
During servicing, keep everybody, especially children,
away.
ELECTRIC SHOCK can kill.
DDo not touch live electrical parts.
DTurn OFF unit, and disconnect and lockout in-
put power using line disconnect switch, circuit
breakers, or by removing plug from receptacle
before servicing unless the procedure specifi-
cally requires an energized unit.
DInsulate yourself from ground by standing or working on dry in-
sulating mats big enough to prevent contact with the ground.
DDo not leave live unit unattended.
DIf this procedure requires an energized unit, have only personnel
familiar with and following standard safety practices do the job.
DWhen testing a live unit, use the one-hand method. Do not put
both hands inside unit. Keep one hand free.
DDisconnect input power plug or conductors from deenergized
supply line BEFORE moving unit.
MOVING PARTS can injure.
DDo not put hands between tips.
DKeep away from pinch points.
DOSHA and/or local codes may require addi-
tional guarding to suit the application.
HOT PARTS can burn.
DDo not touch hot parts bare handed.
DAllow cooling period before working on
equipment.
DTo handle hot parts, use proper tools and/or
wear heavy, insulated welding gloves and
clothing to prevent burns.
FLYING METAL or DIRT can injure eyes.
DWear safety glasses with side shields or face
shield during servicing.
DBe careful not to short metal tools, parts, or
wires together during testing and servicing.
ELECTRIC AND MAGNETIC FIELDS (EMF)
can affect Implanted Medical Devices.
DWearers of Pacemakers and other Implanted
Medical Devices should keep away from serv-
icing areas until consulting their doctor and the
device manufacturer.
SHOCK HAZARD from testing.
DTurn Off unit before making or changing meter
lead connections.
DUse at least one meter lead that has a self-
retaining spring clip such as an alligator clip.
DRead instructions for test equipment.
WELDING can cause fire or explosion.
DProtect yourself and others from flying sparks
and hot metal.
DDo not spot weld where flying sparks can
strike flammable material.
DIf test welds are required, follow Safety Precautions in Owner’s
Manual and on safety label(s).
FALLING EQUIPMENT can injure.
DUse equipment of adequate capacity to lift and
support the unit.
DFollow the guidelines in the Applications
Manual for the Revised NIOSH Lifting Equa-
tion (Publication No. 94−110) when manually
lifting heavy parts or equipment.
DSecure unit during transport so it cannot tip or fall.
OVERUSE can cause OVERHEATING.
DAllow cooling period; follow rated duty cycle.
DReduce duty cycle before starting to weld
again.
READ INSTRUCTIONS.
DUse Testing Booklet (Part No. 150 853) when
servicing this unit.
DConsult the Owner’s Manual for welding
safety precautions.
DUse only genuine replacement parts from the manufacturer.
DRead and follow all labels and the Technical Manual carefully
before installing, operating, or servicing unit. Read the safety
information at the beginning of the manual and in each section.

TM-716 Page 2 MSW And LMSW Series
1.3 California Proposition 65 Warnings
Welding or cutting equipment produces fumes or gases
which contain chemicals known to the State of California to
cause birth defects and, in some cases, cancer. (California
Health & Safety Code Section 25249.5 et seq.)
Battery posts, terminals and related accessories contain
lead and lead compounds, chemicals known to the State of
California to cause cancer and birth defects or other
reproductive harm. Wash hands after handling.
This product contains chemicals, including lead, known to
the state of California to cause cancer, birth defects, or other
reproductive harm. Wash hands after use.
For Gasoline Engines:
Engine exhaust contains chemicals known to the State of
California to cause cancer, birth defects, or other reproduc-
tive harm.
For Diesel Engines:
Diesel engine exhaust and some of its constituents are
known to the State of California to cause cancer, birth
defects, and other reproductive harm.
1.4 EMF Information
Electric current flowing through any conductor causes localized elec-
tric and magnetic fields (EMF). Welding current creates an EMF field
around the welding circuit and welding equipment. EMF fields may in-
terfere with some medical implants, e.g. pacemakers. Protective
measures for persons wearing medical implants have to be taken. For
example, access restrictions for passers−by or individual risk assess-
ment for welders. All welders should use the following procedures in
order to minimize exposure to EMF fields from the welding circuit:
1. Keep cables close together by twisting or taping them, or using
a cable cover.
2. Do not place your body between welding cables. Arrange
cables to one side and away from the operator.
3. Do not coil or drape cables around your body.
4. Keep head and trunk as far away from the equipment in the
welding circuit as possible.
5. Connect work clamp to workpiece as close to the weld as
possible.
6. Do not work next to, sit or lean on the welding power source.
7. Do not weld whilst carrying the welding power source or wire
feeder.
About Implanted Medical Devices:
Implanted Medical Device wearers should consult their doctor and the
device manufacturer before performing or going near arc welding,
spot welding, gouging, plasma arc cutting, or induction heating opera-
tions. If cleared by your doctor, then following the above procedures
is recommended.

TM-716 Page 3MSW And LMSW Series
SECTION 2 −−INTRODUCTION
2-1. Specifications
Model
AC Input
Voltage
50/60 Hz
1-Phase
Work Capacity Com-
bined
Thickness
Uncoated Mild Steel
Rated
Output At
50% Duty
Cycle*
Welder Dimensions Weight
Height Width Length Net Ship
MSW-41T 110 1/8 in.**
(3.2 mm) 1.5 kVA 6 in. (152 mm)
4-1/2 in.
(114 mm)
13 in.
(330 mm)
34 lb
(15.4 kg)
38 lb
(17.2 kg)
LMSW-52T 220 3/16 in.**
(4.7 mm) 2.5 kVA 6 in. (152 mm)
4-1/2. in
(114 mm)
16 in.
(406 mm)
42 lb
(19.1 kg)
45 lb
(20.4 kg)
*Based on 10 second time period; means unit can weld for 5 seconds out of each 10 second time period.
** Not recommended for aluminum or copper alloys.
Model MSW-41, 41T LMSW-52, 52T
Tong Length 6 in.
(152 mm)
12 in.
(305 mm)
18 in.
(457 mm)
6 in.
(152 mm)
12 in.
(305 mm)
18 in.
(457 mm)
Input Volts 110 220
Output Amps 10% 5500 4500 3600 6750 5800 4850
SECTION 3 −INSTALLATION
3-1. Installing Or Dressing Tips
Ref. 800 155-B / Ref. 800 154
!Turn off and unplug welder.
1 Threaded Tip
2 Tip With Hexhead Screw
3 Tong
Coat threads with supplied heat
sink compound and install tip onto
tong. Do not overtighten.
Tools Needed:
A. Installing Tips
3
12
3
3/16 in.
9/16 in.
OR

TM-716 Page 4 MSW And LMSW Series
B. Dressing The Tips
!Turn off and unplug welder.
1 New Tip
2 Used Tip Requiring Dressing
3 Dressing Method −Keep top
diameter same as a new tip.
1
Tools Needed:
d = <1/8 in. (3.2 mm)
diameter
for 1.5 kVA models;
5/32 in. (4 mm)
for 2.5 kVA models
2
3d d
OR
Notes

TM-716 Page 5MSW And LMSW Series
3-2. Installing Or Cleaning Tongs
800 155-A / Ref. 800 154-A
!Turn off and unplug welder.
.Be sure tong ends are clean
and not corroded before
installing. Clean tongs with fine
steel wool.
Bottom Tong:
1 Bottom Tong
2 Hole In Spatter Guard
3 Bottom Tong Securing Screws
(4)
Loosen the four screws. If needed,
use a rubber mallet to loosen tong.
Slide tong into bottom tong holder
as far as possible, and position so
that tip is pointing straight up.
Loosely tighten screws.
Top Tong:
4 Top Tong
5 Top Tong Holder/Pivot Casting
6 Top Tong Securing Screws (4)
Loosen the four screws. If needed
for removal, use a rubber mallet to
loosen tong.
Slide tong into pivot casting as far
as necessary, so that tip mates with
bottom tip when tongs are closed.
Loosely tighten screws.
7 Tips
Adjust tong positions to line up cen-
ters of tips as shown. Tighten
screws.
1
2
4
5
6
3
1
44
1
77
Tools Needed:
3/16 in.
9/16 in.
Front View Side View
Tong Alignment
7
Fine
Steel
Wool
!OSHA and/or local codes may require
additional guarding to suit the application.

TM-716 Page 6 MSW And LMSW Series
3-3. Adjusting Tong And Hand Lever Pressure
!Turn off and unplug welder.
!Excessive tong pressure can dam-
age tips. Do not use tongs as a clamp
or vice to hold workpiece together. If
the two pieces of material to be
welded do not make good contact at
the point of the intended weld, clamp
material to provide good contact be-
tween surfaces.
.Tong pressure is adjustable, and must
be checked and/or set before operation.
Correct tong pressure is necessary to
create a quality weld and to prevent
damage to tips.
Too much tong pressure causes the
weld nugget to dimple and material to
splash out around the nugget area.
If tong pressure is too weak, parts are
loose when the tongs close, severe arc-
ing occurs between workpieces, and no
weld can be made.
1 Front Nut
2 Rear Nut
3 Pivot Casting
4 Hand Lever
5 Tongs
To increase tong pressure, loosen front nut.
The farther the front nut is turned out, the
greater the pressure on the tips when the
hand lever is closed. Turn the rear nut up to
the pivot casting to lock the position.
To decrease tong pressure, loosen the rear
nut and turn the front nut up to the pivot cast-
ing.
6 Machine Screw
The farther down the screw is turned, the far-
ther the hand lever will close. Adjustment of
this screw will determine if the tongs lock on
the material, or just pull up tight. Adjust screw
to allow lever to be raised easily after the
weld has been completed.
7 Hex Nut
To adjust pressure needed to push down
hand lever, turn the hex nuts located on each
side of the pivot casting.
Tools Needed:
1
2
3
4
5
6
7
Ref. 800 156
9/16, 11/16 in.

TM-716 Page 7MSW And LMSW Series
3-4. Installing Handle
!Turn off and unplug welder.
1 Wooden Handle
2 Handle Bolt
3 Brackets (41 And 41T Models Only)
Install handle onto the spot welder as shown
above. For 52, and 52T Models, install han-
dle onto either side as desired for either right-
hand or left-hand use.
Tools Needed:
Ref. 802 056-A
7/16, 3/8 in.
MSW 52, And 52T Models
MSW 41 And 41T Models
2
1
3
1
2
1
2

TM-716 Page 8 MSW And LMSW Series
3-5. Mounting Control Box
800 233-A
Push-in slots are provided on rear
of box for wall mounting if desired.
The slots will fit over 1/4 inch hex-
head screws. To mount box, pro-
ceed as follows:
1 Control Box
2 Push-In Slots (Not Shown)
Use slots as template and install
screws at desired locations leaving
1/8 inch stickout.
Push rear slots firmly against screw
heads, and slide box down onto
screws.
1
2
OR
3-6. Connecting Input Power (T Models)
Ref. 800 233-A
Operate spot welder from a sepa-
rately fused or circuit breaker pro-
tected circuit, and use correct size
input conductors.
1 Rating Label (Not Visible As
Shown On Spot Welder)
2 Cord
3 Parallel Plug On 110 Volts AC
Models
4 Tandem Plug On 220 Volts
AC Models
Do not cut ground terminal off plug.
5 Grounded Receptacle
Connect plug to matching
grounded receptacle.
Model
Input Conductor
Size (AWG)
Fuse/Circuit Breaker
Size In Amperes
1.5 kVA 110 Volt
1.5 kVA 220 Volt
2.5 kVA 220 Volt
No. 10
No. 12
No. 10
30
15
30
2
3
4
5
1
OR
1

TM-716 Page 9MSW And LMSW Series
3-7. Connecting Input Power (Non-T Models)
Ref. 800 156
!Input power supply wiring
and receptacle must meet
National Electrical Code and
all other code requirements.
Operate spot welder from a sepa-
rately fused or circuit breaker pro-
tected circuit, and use correct size
input conductors.
1 Rating Label
2 Cord
3 Parallel Plug On 110 Volts AC
Models
4 Tandem Plug On 220 Volts
AC Models
Do not cut ground terminal off plug.
5 Grounded Receptacle
Connect plug to matching
grounded receptacle.
12
3
Or
4
5
Model
Input Conductor
Size (AWG)
Fuse/Circuit Breaker
Size In Amperes
1.5 kVA 110 Volt
2.5 kVA 220 Volt
No. 10
No. 10
30
30
Notes

TM-716 Page 10 MSW And LMSW Series
SECTION 4 −OPERATION
4-1. Controls (T Models)
146 013-B
1 Spot Weld Timer And Pilot
Light
Weld time adjusts from 0 to 5
seconds. The pilot light turns on
when the weld cycle begins and off
when the cycle ends.
2 Hand Lever
Use lever to open and close tongs.
Close the hand lever during the
welding process to compress the
material between the tips. To adjust
tong pressure, see Section 3-3.
3 Start Switch
Move start switch sideways in ei-
ther direction to start weld cycle.
When weld cycle time ends, or the
start switch is released, weld output
stops, and the timer resets for
another weld cycle.
4 Power Switch
2
3
1
4
4-2. Controls (Non-T Models)
145 104-A
1 Hand Lever
Use lever to open and close tongs.
Close the hand lever during the
welding process to compress the
material between the tips. To adjust
tong pressure, see Section 3-3.
2 Start Switch
Use switch to turn weld current On
and Off. Move switch sideways in
either direction to start weld current.
Release switch to stop weld cur-
rent.
1
2

TM-716 Page 11MSW And LMSW Series
SECTION 5 −THEORY OF OPERATION
Main
Transformer
T1
8
1 Input Power Plug PLG1
Provides connection for line input
power.
2 Power Switch S1
Turns unit On/Off.
3 Control Transformer T2
(220 V Models)
Supplies power to spot timer control
circuit.
4 Fuse F1 (220 V Models)
Provides overload protection for
T2.
5 Start Switch PB1
Turns weld current On/Off.
6 Spot Weld Delay Timer TD1
And Pilot Light PL1
TD1 provides 0 to 5 seconds of
weld time.
PL1 turns on when weld cycle be-
gins and turns off when weld cycle
ends.
7 Contactor W
Connects line input power to main
transformer T1.
8 Main Transformer T1
Supplies power to weld output cir-
cuit. The transformer steps up the
current and steps down the voltage.
Resistance spot welds are made
with very low voltage (1-3 volts)
and with very high current
(4000-5000 amperes) applied un-
der pressure for a brief time period
(1-3 seconds) which causes in-
tense localized heating and a weld.
Weld Current Circuit
AC Control Circuits
1Power
Single-Phase
Line Input
Power Input
1
Power
Plug PLG1
Power
2
Switch
S1
Start
5
Switch
PB1
6
Contactor
7
W
TD1
110 Volts Model With A Timer
Single-Phase
Line Input
Power Input
1
Power
Plug PLG1
Power
2
Switch
S1
Control
3
Fuse
4
Transformer
T2
F1
W
220 Volts Models With A Timer
Spot Weld
Delay Timer
TD1 And
Pilot Light
PL1
Main
Transformer
T1
8
W
Start
5
Switch
PB1
6
Contactor
7
TD1
W
Spot Weld
Delay Timer
TD1 And
Pilot Light
PL1

TM-716 Page 12 MSW And LMSW Series
1 Input Power Plug
Provides connection for line input
power.
2 Start Switch S1
Turns weld current On/Off.
3 Main Transformer T1
Supplies power to weld output cir-
cuit. The transformer steps up the
current and steps down the voltage.
Resistance spot welds are made
with very low voltage (1-3 volts)
and with very high current
(4000-5000 amperes) applied un-
der pressure for a brief time period
(1-3 seconds) which causes in-
tense localized heating and a weld.
Main
Transformer
T1
3
Weld Current Circuit
AC Control Circuits
1Power
Single-Phase
Line Input
Power Input
1
Power
Plug
Start
2
Switch
S1
For Models Without A Timer

TM-716 Page 13MSW And LMSW Series
SECTION 6 −TROUBLESHOOTING
6-1. Troubleshooting Table
.See Sections 6-2, 6-3 and 6-4 for test points and val-
ues and Section 9 for parts location.
.Use Miller Testing Booklet (Part No. 150 853) when
servicing this unit.
.See the Miller Extranet for service memos that may
aid in the repair of this product.
Trouble Remedy
No weld output. Check and replace line fuses or reset circuit breaker. If line fuses or circuit breaker continues to open,
check main transformer T1 and control transformer T2 if applicable.
For 220 V models effective with Style No. JA41, check fuse F1, and replace if necessary (see Section
7-2).
Check continuity of input power cord and plug PLG1, and replace if necessary.
Check continuity of interconnecting cord, and replace if necessary.
Check continuity of Power switch S1, and replace if necessary.
Check continuity of start switch PB1, and replace if necessary.
Check coil voltage and connections of contactor W. Check continuity of coil and condition of contacts.
Replace W if necessary.
Check main transformer T1 for signs of winding failure. Check continuity across winding, and check for
proper connections. Replace T1 if necessary.
For 220 V models, check control transformer T2 for signs of winding failure. Check continuity across wind-
ings, and check for proper connections. Replace T2 if necessary
No weld output; input line circuit
breakers or fuses trip or blow repeatedly.
Possible internal short-circuit. Check bottom tong clamp insulation (2 pieces −see Section 9, Parts List)
for cracks or arc tracks. Replace insulation if necessary.
Possible internal short-circuit. Check main transformer insulation (2 pieces −see Section 9, Parts List)
for cracks or arc tracks. Replace insulation if it is burned through or worn.
Low weld output. Dress or replace tips (see Section 3-1).
Check tip threads. Replace tips if necessary (see Section 3-1).
Remove and clean tongs. Remove insulator plugs from front housing, and blow out tong holders with com-
pressed air (see Section 3-2).
Clean ends of tongs and tong holders (see Section 3-2).
Check Power switch S1 contacts for pitting and wear. Replace S1 if necessary.
Check start switch PB1 contacts for pitting and wear. Replace PB1 if necessary.
Check contactor W contacts for pitting and wear. Replace W if necessary.
Check tong braid for loose connections, fraying, or overheating. Replace tong braid if necessary.
Longer than normal weld time required. Dress or replace tips (see Section 3-1).
Clean workpieces.
Adjust tong pressure (see Section 3-3).
Clean ends of tongs and tong holders (see Section 3-2).
Check input line voltage.
Check contactor W contacts for pitting and wear. Replace W if necessary.
Burn through at point of weld. Shorten weld time.
Adjust tong pressure (see Section 3-3).
Dress or replace tips (see Section 3-1).
Realign tips (see Section 3-2).
Tips overheating. Not enough tong pressure. Increase tong pressure.
Weld time too long. Reduce weld time.
Material too thick for the spot welding machine.

TM-716 Page 14 MSW And LMSW Series
Tips arcing on material. Not enough tong pressure. Increase tong pressure.
Tips not aligned correctly. Realign tips or dress tips to proper diameter (see Section 3-1).
Base material may be welded to tips causing high resistance and poor electrical current flow. Clean or
dress tips (see Section 3-1).
Spatter or molten material being ex-
pelled out during welding operation.
Incorrect tip alignment. Dress tips so that they align and are flat on the material (see Section 3-1).
Excessive tong pressure. Reduce tong pressure.
Output amperage too high. Reduce amperage setting, if applicable (not available on air-cooled mod-
els).
Weld time too long. Reduce weld time.
Inconsistent weld nugget. Inconsistent weld time. Install a weld timer, if applicable.
Not enough tong pressure. Increase tong pressure.
Hole in middle of weld. Contact area of tips is too large. Change to a smaller tip diameter or dress tips back to original diame-
ter (see Section 3-1).
Poor weld or no weld at tips. Material too thick for spot welding machine. Check that material thickness is within capacity of spot
welding machine.
Tongs are too long. Reduce tong length.
Remove coating from material for intimate contact between pieces. Remove oxides and chemical
compounds including galvanized coating.
Spot weld delay timer TD1 not
functioning properly.
Be sure that all spot weld delay timer TD1 leads are secure.
Replace spot weld delay timer TD1.
Notes

TM-716 Page 15MSW And LMSW Series
6-2. Troubleshooting Circuit Diagram For 1.5 KVA (110 Or 220V) And 2.5 KVA
(220V) Models
Resistance Values
a) Tolerance −10% unless specified
b) Turn Off unit and disconnect plug
before checking resistance
R1 0.4 ohms (110V, 1.5 kVA models)
R1 0.8 ohms (220V, 2.5 kVA models)
R1 1.1 ohms (220V, 1.5 kVA models)
Test Equipment Needed:
162 467-B
Voltage Readings
a) Tolerance −10% unless specified
b) Reference −as indicated
c) Wiring Diagram −see Section 8
V1 115 or 230 volts AC
V2 115 or 230 volts AC with S1 closed
V3 1.6 volts AC open-circuit voltage (1.5 kVA)
V3 2.5 volts AC open-circuit voltage (2.5 kVA)
V1
See Section
6-5 for
waveforms A,B
V2/R1
V3
A,B

TM-716 Page 16 MSW And LMSW Series
6-3. Troubleshooting Circuit Diagram For 1.5 KVA, 110 Volts Model
Resistance Values
a) Tolerance −10% unless specified
b) Turn Off unit and disconnect plug
before checking resistance
R1 0.4 ohms
Test Equipment Needed:
162 466-C
A
Voltage Readings
a) Tolerance −10% unless specified
b) Reference −as indicated
c) Wiring Diagram −see Section 8
V1 115 volts AC
V2 115 volts AC with S1 closed
V3 115 volts AC with PB1 closed
V4 115 volts AC with PB1 closed and TD1 not
timed out
V5 115 volts AC with W energized
V6 1.6 volts AC open-circuit voltage
V6
V2 V3
V1
V2
Contactor W
V4
V3
See Section
6-5 for
waveform A
V5/R1

TM-716 Page 17MSW And LMSW Series
6-4. Troubleshooting Circuit Diagram For 1.5 And 2.5 KVA, 220 Volts Models
Resistance Values
a) Tolerance −10% unless specified
b) Turn Off unit and disconnect plug
before checking resistance
R1 1.5 kVA, 220 V model: 1.1 ohms
2.5 kVA, 220 V model: 0.8 ohms
Test Equipment Needed:
072 065-C
Voltage Readings
a) Tolerance −10% unless specified
b) Reference −as indicated
c) Wiring Diagram −see Section 8
V1 230 volts AC
V2 230 volts AC with S1 closed
V3 115 volts AC with S1 closed
V4 115 volts AC with PB1 closed
V5 115 volts AC with PB1 closed and TD1 not
timed out
V6 230 volts AC with W energized
V7 1.5 kVA, 220 V model: 1.6 volts AC
open-circuit voltage
2.5 kVA, 220 V model: 2.5 volts AC
open-circuit voltage
A, B
V7
See Section
6-5 for
waveforms A, B
V6/R1
V3 V4
V1 V2
V5
V4
V3
Contactor W

TM-716 Page 18 MSW And LMSW Series
6-5. Waveforms For Sections 6-2, 6-3 And 6-4
5 ms 2 V
A. AC Open-Circuit Voltage For 1.5 KVA
Models
5 ms 2 V
B. AC Open-Circuit Voltage For 2.5 KVA
Model
Test Equipment Needed:
gnd gnd