Thermo Scientific PRECISION 2878 Manual

Installation/Service Manual
Chiron Circulating Water Baths
Model 2878 (120V)
Model 2879 (230V)
401MillcreekRoad
Marietta,Ohio45750
USA
Phone:[phone]
TollFree: 800-438-4851
FAX:[phone]
ManualP/N3183922(36100178)
Rev.D Dated15APR09
High Temp. Off
On

NOTICE
THE MATERIAL IN THIS MANUAL IS FOR INFORMATION PURPOSES ONLY. THE
CONTENTS AND THE PRODUCT IT DESCRIBES ARE SUBJECT TO CHANGE WITHOUT
NOTICE.THERMOSCIENTIFICMAKESNOREPRESENTATIONSORWARRANTIESWITH
RESPECT TO THIS MANUAL. IN NO EVENT SHALL THERMO BE LIABLE FOR ANY
DAMAGES,DIRECTORINCIDENTAL,ARISINGOUTOFORRELATEDTOTHEUSEOFTHIS
MANUAL.
Forrepairinformationorreplacementpartsassistancefromthemanufacturer,callTechnicalServicesusingourtoll
freetelephonenumber.
800-438-4851
(FAX)740-373-4189

INDEX DATE NOTES
REVISION STATUS
Initial releaseA
AMENDED PAGES
4/04
Updatewarrantyinfo
RemovedScreenAssemblyOption
andother changes ECR 22856
ECR25448/BA-670
B
C
D
9/04
10/05
4/09
27
--
ULrequiredinfo

Contents
INTRODUCTION.................................................................................................................. 1
UNPACKING AND DAMAGE .............................................................................................. 1
GENERAL INFORMATION.................................................................................................. 2
PERFORMANCE................................................................................................................. 2
INSTALLATION ................................................................................................................... 2
WATER LEVEL REGULATOR ........................................................................................... 3
EXPLANATION OF CONTROLS ........................................................................................ 5
OPERATION ........................................................................................................................ 6
MAINTENANCE................................................................................................................... 7
TROUBLESHOOTING ........................................................................................................ 7
PARTS REPLACEMENT .................................................................................................. 12
TEMPERATURE CALIBRATION ...................................................................................... 15
REPLACEMENT PARTS LIST ......................................................................................... 16
ASSEMBLY & SCHEMATIC DWGS ................................................................................. 18
WARRANTY ...................................................................................................................... 27

1
UNPACKING AND DAMAGE
Save all packing material until unit is put into
service. This merchandise was carefully packed
andthoroughlyinspectedbeforeleavingourfactory.
Responsibility for safe delivery was assumed by
the carrier upon acceptance of the shipment;
therefore, claims for loss or damage sustained in
transit must be made upon the carrier by the
recipient as follows:
1. Visible Loss or Damage: Note any external
evidenceofloss or damageonthefreight bill,
or express receipt, and have it signed by the
carrier'sagent. Failuretoadequatelydescribe
such external evidence of loss or damage
may result in the carrier's refusing to honor
your damage claim. The form required to file
such claim will be supplied by the carrier.
2. Concealed Loss or Damage: Concealed
lossordamagemeansloss or damage which
does not become apparent until the
merchandise has been unpacked and
inspected. Shouldeitheroccur,makeawritten
requestforinspectionbycarrier'sagentwithin
fifteen (15) days of the delivery date; then file
a claim with the carrier since the damage is
the carrier's responsibility.
If you follow the above instructions carefully, we
will guarantee our full support of your claim to be
compensated for loss or concealed damage.
DONOT—FORANYREASON—RETURNTHIS
UNIT WITHOUT FIRST OBTAINING
AUTHORIZATION. In any correspondence to
THERMO, please supply the nameplate data,
including catalog number and serial number.
INTRODUCTION
Your satisfaction and safety are important to
THERMO and a complete understanding of this
unit is necessary to attain these objectives.
As the user of this apparatus, you have the
responsibility to understand the proper function
and operational characteristics of your bath. This
instruction manual should be thoroughly read and
all operators given adequate training before
attemptingtoplacethisunit inservice. Awareness
of the stated cautions and warnings, and
compliance with recommended operating
parameters — together with maintenance
requirements — are important for safe and
satisfactoryoperation. Theunitshouldbeusedas
described in this manual and for its intended
purpose; alterations or modifications will VOID
THE WARRANTY.
WARNING
AS A ROUTINE LABORATORY PRECAUTION,
ALWAYS WEAR SAFETY GLASSES WHEN
WORKING WITH THIS APPARATUS.
Thisproductisnotintended,nor canitbeused,as
a sterile or patient connected device. In addition,
this apparatus is not designed for use in Class I, II
orIIIlocationsasdefinedbytheNationalElectrical
Code.

2
PERFORMANCE DATA
Thefollowing table identifiesthespecificationsfor
the Circulating Baths.
INSTALLATION
WARNING
INSTALLATION SHOULD BE COMPLETED BY
QUALIFIED PERSONNEL ONLY.
Location-Themostuniformoperatingconditions
will be obtained by placing the bath on a level
surface in an area remote from drafts, ventilating
outlets, radiators, and other rapidly changing
ambient conditions.
Environmental Conditions- This instrument is
designed to operate safely under the following
conditions:
• Indoor Use Only
• Temperature: 5° to 40°C
• Maximum Relative Humidity: 80% for
temperatures to 22°C
• Maximum Altitude 2000 meters
• Mains supply voltage fluctuation ±10, or
per project plan
• Installation (Overvoltage) category II1,
Pollution Degree 22
1Installationcategory (overvoltagecategory)defines
thelevel of transient overvoltage which the instrument
is designed to withstand safely. It depends on the
natureof the electricity supply and its overvoltage
protection means. For example, in CAT II which is
the category used for instruments in installations
supplied from a supply comparable to public mains
such as hospital and research laboratories and most
industriallaboratories, theexpected transient
overvoltageis 2500Vfor a 230V supply and 1500V for
a120V supply.
2 Pollution Degree describes the amount of
conductivepollution present in the operating
environment.Pollution Degree2 assumesthat
normallyonly non-conductivepollution suchas dust
occurswith the exceptionof occasional conductivity
causedby condensation.
GENERAL INFORMATION
Precision Circulating Baths are widely used in
research and quality control. Their superb
temperature uniformity and stability makes them
especially desirable for legal or reference tests.
The microprocessor control panel houses all
functions necessary to operate the bath. The 5
push-button switches and single digital display
window allow the operator to adjust bath
temperatureandtemperaturecalibrationviaasingle
set of controls.
The proportional integral temperature control
coupled with agitation supplied by a centrifugal
pumplocatedinthecontrolhousingallowsprecise
temperaturecontrol. Useofthegablecoverprovided
is required to maintain optimal temperature
sensitivity.
A high limit thermostat is provided and can be set
to prevent heater runaway in the event of
temperature control failure.
The interior of the bath is constructed of stainless
steel and is designed for operation with distilled
water or water solutions, such as water /ethylene
glycolwithcorrosioninhabitantsadded. Thebody
is made from galvanized steel and is painted for
added protection. A drain is located at the far left
handendofthebath. Astainlesssteelgablecover
is also provided with the bath.
The 230-volt units are identical in appearance to
the 120-volt units.
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3
WATER LEVEL REGULATOR
(OPTIONAL)
INSTALLATION INSTRUCTIONS - Use the
following steps along with Fig. 1 & 2 shown on the
followingpage.
1. Turn off unit, disconnect power & drain water
from the bath.
2. Unscrew drain plug from side of bath body.
3. Replacewithelbowconnector(shippedloose).
NOTE
TO INSURE GOOD SEAL, WRAP THREADS
WITH TEFLON TAPE OR EQUIVALENT
SEALER.
4. Tighten elbow connector so open end (tube
fitting) faces straight down.
5. PlaceWaterLevelRegulatorBkt.Ass'yonthe
lip of the bath pan (drain side of the bath
towards the rear of the unit). The small flange
with gasketing near the top of the bracket
should rest against the inside of the bath pan.
The other 2 flanges with gasketing should
rest against the outside of the bath body.
6. Insert the plastic tubing (coming from the
bottom of the water level regulator) into the
elbow connector (at the drain) & tighten the
elbow connector fitting firmly to insure a good
seal.
7. Uncoil Tygon tubing & press onto 1/4" Hose
Barb Fitting (located at the top of water level
regulator).
8. Hook-upotherendofthetygontubingtowater
supply&turnonwater.(Waterpressureshould
fallwithinthefollowingrange:MINisapprox.15
PSI,MAX isapprox 75PSI)
ELECTRICAL CONNECTIONS
IMPORTANT
Forpersonalsafety,thisapparatusmustbe
properlygrounded.
1. Thepowercordprovidedonthisunitisequipped
with a three-prong (grounding) plug which
mates with standard three-prong grounding
wall receptacle to minimize the possibility of
electric shock hazard from this apparatus. If
in doubt, the user should have the wall
receptacle and circuit checked by a qualified
electrician to make sure the receptacle can
provide adequate current and is properly
grounded.
The power cord is the MAINS disconnect.
Make sure the receptacle is easily accessible
afterinstallation.
2. Where a standard two-prong wall receptacle
isencountered,itisthepersonalresponsibility
and obligation of the user to have it replaced
with a properly grounded three-prong wall
receptacle. Donot,underanycircumstances,
cut or remove the third (ground) prong from
thepowercord.Donotuseatwo-prongadapter
plug.
Determine the total amount of current being used
byotherapparatusconnectedtothecircuitthatwill
be used for this apparatus. It is critical that the
addedcurrentdemand(seenameplate)ofthisand
otherequipmentusedonthesamecircuitdoesnot
exceed the rating of the fuse or circuit breaker.
CAUTION
BE SURE THAT THE POWER SUPPLY IS OF
THE SAME VOLTAGE AS SPECIFIED ON THE
NAMEPLATE.
TO AVOID BUILD-UP OF MINERAL DEPOSITS
AND TO PREVENT CORROSION, USE ONLY
DISTILLED WATER (50K TO 1M OHMS) IN THE
BATH.DONOTUSEDEIONIZEDWATER,OVER
TIME, IT BECOMES CORROSIVE AND WILL
ATTACK STAINLESS STEEL. IF DEIONIZED
WATER IS THE ONLY TYPE AVAILABLE, THEN
USE A MIXTURE OF WATER WITH A RATIO OF
50%DEIONIZEDWATERAND50%TAPWATER.
ELECTROLYSIS CAN DAMAGE STAINLESS
STEEL. THIS CAN OCCUR IF AN OBJECT IS
ALLOWED TO REST DIRECTLY ON THE
SURFACE, TRAPPING MOISTURE THAT
BECOMES OXYGEN STARVED BUT IS
SURROUNDED BY WATER CONTAINING

4
WATER LEVEL REGULATOR ASSEMBLY
FIGURE 1
SIDE VIEW OF BATH
FIGURE 2
CUTAWAY FRONT VIEW OF BATH
NOTE
WATER LINE
MARKING ON THE
WATER LEVEL
REGULATOR IS AN
INDICATOR OF THE
APPROX. WATER
LEVEL THAT WILL BE
MAINTAINED IN BATH.
THE ASS'Y HAS BEEN
SET TO MAINTAIN
APPROX. 1-3/4" OF
WATER. TO RAISE
THE SET WATER
LEVEL, LOOSEN
THUMBSCREW &
RAISE WATER LEVEL
REGULATOR TO
DESIRED LEVEL
(COINCIDE WITH
WATER LINE MARK) &
TIGHTEN
THUMBSCREW TO
HOLD WATER LEVEL
REGULATOR IN
PLACE.
NOTE:
DO NOT
OVER-TIGHTEN
THUMBSCREW

5
1
2
4
3
5
67
FIGURE A
EXPLANATION OF CONTROLS
Power Switch - The power switch is located on
the lower right hand side of the bath, it provides
power for the entire unit.
Hi-Limit Thermostat - is located immediately to
theleftofthepowerswitchonthelowerrighthand
cornerofthe bath. The highlimitis an adjustable
control used to prevent thermal runaway in the
event that the primary control fails. After the bath
temperature has been stabilized, use a standard
screwdriver to adjust the potentiometer. When
delivered, the Hi-Limit is turned fully clockwise
(highest setting). In this position the Hi-Limit light
will be OFF. Turn the potentiometer
counterclockwise until the Hi-Limit light is ON,
then adjust
clockwise 1/8 of
aturn.Verifythat
the Hi-Limit light
is OFF. Now if
your bath
temperature
rises above the
desired setting,
the Hi-Limit
protectionwillbe
activated.
Control Panel
The Control
panel is located
ontopofthebath
andprovidespri-
mary tempera-
ture control. The
Control Panel
contains the fol-
lowing features
(See Figure A)
1. LED Display
4-digit display used to show both actual and set
point values for the temperature. Also shows
configuration parameters when in configuration
mode.
2. Heater on Lamp - the Heater on Lamp is
lighted when power is applied to the heating
element.
3. Indicator Lamps - These lamps indicate
which parameter (Actual Temp or Setpoint Temp)
is displayed in LED window.
4. Set Point Key - The Set Point Key is used to
toggle the display between actual bath
temperature and the setpoint value.
5. Temperature
Selection Keys
The Temperature
Selection Keys
are used to
select the de-
sired tempera-
ture setpoint
value and
are only active
after theSet Point
Key has been
pressed.
6. Enter Key -
The Enter Key
is used to store
a new set point
value.
7. Offset Key -
The Offset Key
is used to adjust
the actual
temperature
value to match
a calibrated
reference
thermometer.
OXYGEN. THE
RESULTING
ELECTROLYTIC
ACTION WILL
PIT OR ERODE
THE
STAINLESS
STEEL.

6
OPERATION
CAUTION:
EXERCISE CARE WHEN USING ACIDIC OR
CAUSTIC SOLUTIONS AS THEY WILL ATTACK
THEGALVANIZEDSTEELBATHBODYIFSPILLED
INTOTHEBATH.IFSPILLSDOOCCUR,THEBATH
LIQUIDSHOULDBEIMMEDIATELYDRAINEDAND
THE UNIT THOROUGHLY FLUSHED. SPILLS AND
CONDENSATION SHOULD BE CLEANED/
REMOVED FROM ALL METAL SURFACES AFTER
EACH USE.
Whenfillingthebathwithwater,allowancemustbe
madeforthedisplacementofwateruponimmersion
of samples.
CAUTION
WATER LEVEL REQUIREMENTS
MINIMUM LEVEL - WATER LEVEL SHOULD BE
1 1/2 INCHES ABOVE THE PUMP OUTLET.
THIS WILL KEEP THE PUMP FROM RUNNING
DRY AND FAILING TO OPERATE.
MAXIMUM LEVEL - WATER LEVEL SHOULD
NOT BE HIGHER THAN 1 INCH FROM THE
TOP OF THE BATH PAN.
To conserve energy, reduce evaporation and
increase temperature control accuracy, use the
gablecoverprovided. Do notusealuminumfoil as
a cover, as it may cause corrosion due to an
electrochemical reaction.
1. Adddistilledwatertobath. Usewaterlevelsas
instructed above.
2. Power up: Depress the power switch located
atthe lowerrighthandcornerofthebath. The
unit is fully operational upon application of
power and the display will read actual bath
temperature
3. To set temperature control point:
a. Press SETPOINT. The display will now
show the current temperature setpoint.
b. Press UP or DOWN until the desired
temperature setpoint is displayed.
c. Press ENTER to store the new value.
d. Display will return to actual temperature.
e. IfENTERisnotpressed,newvaluewillnot
be set and display will return to actual
temperature.
4. To adjust temperature offset:
a. Temperature offset should be used to
match a stable bath's actual temperature
display to a calibrated thermometer.
b. Press ENTER until actual temperature is
displayed.
c. While pressing OFFSET, press UP or
DOWN until display shows the
DIFFERENCE between displayed
temperature and reference thermometer.
ContinueholdingoffsetandpressENTER
to set new value.
d. Displayshouldnowmatchyourcalibrated
thermometer.
e. IfENTERisnotpressed,newvaluewillnot
be set and display will return to previous
actual temperature.
f. Example: Setpoint is 37° and actual bath
temperature display is stable at 37°.
Calibrated reference thermometer reads
37.2°.PressOFFSETandUPuntildisplay
reads .2. Press ENTER while still holding
OFFSET key. Release keys. Actual bath
temperature will read 37.2°. Readjust
setpoint to 37° by repeating step 3.
NOTE
AS WATER BATHS ARE OPERATED,
ESPECIALLYATELEVATEDTEMPERATURES,
CONDENSATION WILL FORM ON THE
UNDERSIDE OF THE GABLE COVER. THE
AMOUNT OF CONDENSATION CAN BE
CONSIDERABLE. CARE SHOULD BE
EXERCISED WHEN REMOVING THE COVER
SO THAT WATER WILL FALL BACK INTO THE
BATH CHAMBER, AND NOT ON THE BATH
SURFACE. THE COVER SHOULD BE PLACED
UPSIDE DOWN WHEN REMOVED TO
MAINTAIN A DRY WORK AREA.

7
MAINTENANCE
Cleaning: Stainless steel will resist corrosion;
however, it is not impervious to it. Proper
maintenance of the stainless steel bath chamber
will help assure many years of service.
CAUTION
AVOID SPILLING HARSH CHEMICALS
ONTO THE BATH, AS CORROSION OF
THE STAINLESS STEEL MAY RESULT.
CLEAN-UP AND DECONTAMINATION FROM
SPILLS OF HAZARDOUS MATERIALS ARE
THE RESPONSIBILITY OF THE USER.
It should be cleaned regularly with mild soapy
waterandrinsedwithdistilledwater. Shouldalgae
or other undesirable microorganisms form on the
top of the bath media, add a little formaldehyde or
quaternary ammonium germicide, available from
Thermo (P/N 3166250).
Before using any cleaning or decontamination
method except those recommended by the
manufacturer, users should check with the
manufacturer that the proposed method will not
damage the equipment.
IMPORTANT
IFITISNECESSARYTOUSETHEFOLLOWING
CHEMICALS, LIMIT THE TIME TO A MAXIMUM
OF FOUR HOURS. CLEAN SURFACES
IMMEDIATELY AFTER USE.
-Aluminum Chloride -Barium Chloride
-Bichloride of Mercury -Calcium Chloride
-Carbolic Acid -Chlorinated Lime
-Citric Acid (boiling) -Dakin's Solution
-Ferrous Chloride -Mercury Salts
-LysolMercuric Chloride -Phenol
-Potassium Permanganate -Tartaric Acid
-Potassium Thiocyanate -Stanous Chloride
-Sodium Hypochlorite
CAUTION
NEVER USE THE FOLLOWING CHEMICALS:
-Aqua Regia -Ferric Chloride
-Iodine -Sodium Azide
-Sulfuric Acid
Removing Discoloration: Should the stainless
steel ever become discolored by iron rust, use the
followingproceduretoremovealltracesoftherust
and restore the stainless steel.
WARNING
OBSERVE THE FOLLOWING SAFETY
PRECAUTIONS! USE HEAVY GLOVES OR
OTHER ADEQUATE HAND PROTECTION.
WEARGOGGLES OR OTHERADEQUATE EYE
PROTECTION. ONLY WORK IN AREAS WITH
ADEQUATE VENTILATION.
Prepare a solution of 20% nitric and 1.5%
hydrochloricacid(ifpreferred,a2%to5%solution
of warm oxalic acid may be used). Swab solution
over surface, allowing it to remain until all rust is
loosened. This will usually take 1 to 2 minutes.
Assoonasrustisloosened,immediatelyflushwith
clean water until all acid is removed.
Periodic Safety Check
Test the operation of the Hi-Limit thermostat, as
described on page 5, every three months.
TROUBLESHOOTING
WARNING
SERVICE SHOULD BE PERFORMED BY A
QUALIFIED TECHNICIAN. BEFORE REPLACING
ANY ELECTRICAL OR MECHANICAL
COMPONENTS, UNPLUG THE LINE CORD. IF
ELECTRICAL POWER IS REQUIRED FOR
SERVICE, USE EXTREME CARE.
RefertoProblemsandSolutionsfortroubleshooting
information on the baths. This guide provides the
basic information required to repair the bath.
The following is a list of the tools and instruments
required to perform the procedures outlined in the
Troubleshooting Procedures table.

8
the power supply board at J102 and then
repeat steps 3 through 6. Do not connect the
connectortotheCPUboardatthistime. Ifthe
above voltages are not measured again, the
display board has a bad component which is
loadingdown thevoltages. Ifthevoltagesare
still present, continue on to step 9.
9. Connectthedisplayboardribbonconnectorto
theCPUboardJ310andrepeatsteps3through
6. If the above voltages are not measured
again, the CPU board has a bad component
which is loading down the voltages. This
board will have to be replaced.
GENERAL INFORMATION: The POWER
SUPPLYPCBASSEMBLY#3176677hasthetriac
(solidstateACvoltageswitch)onitwhichsupplies
the power to the heater. This triac is "told" to
operate, when need be, by the microprocessor.
Thereisanotherdeviceknownasanopto-coupler
which serves as the high/low voltage isolator
between the triac and the microprocessor.
When the bath starts experiencing temperature
problemand/orvariations,duetoknowncontroller
malfunctioning, these two components become
primesuspects. The reasonbeing they are under
higher operating stress than other components.
Ifthebathstartsexperiencingtemperatureproblems
such as no heat, or "creeping" upward heat, then
follow the troubleshooting instructions below.
These instructions require the use of a voltmeter
being able to measure DC and AC voltages
(preferably digital) and an ohmmeter.
WARNING
THE FOLLOWING TROUBLESHOOTING
INSTRUCTIONS REQUIRE THAT POWER BE
ON. ONLY QUALIFIED SERVICE PERSONNEL
SHOULD PERFORM THESE PROCEDURES.
ToolsNeeded:
• Phillips or Flat Blade Screwdriver
• 7/16" Socket or adjustable wrench
• Ohmmeter
• DC Voltmeter
• ACVoltmeter
• 5VDC Power Supply
When changing circuit boards, please use
CAUTION when re-installing the flat cable
connectors that come from the display board.
MakesurethepinsareNOTbentorbroken. Boards
that are otherwise fine will not operate correctly if
thesepinshavebeenabusedbecausetheywillnot
receive the necessary signals from other boards.
Before attempting any troubleshooting for a
particular problem, it is good practice to verify
power supply voltages of the POWER SUPPLY
board #3176677. Read these steps before
performing them to get acquainted with the
procedure.
1. Be sure that the main power source is OFF or
disconnected.
2. Connect J101 and J105 to the POWER
SUPPLY BOARD. DO NOT connect J102
that comes from the CPU and the DISPLAY
at this time.
3. Connect the negative lead of the voltmeter to
TP2-COM. SelectaVDCof20. Connectthe
positive lead to TP1 - UNREG.
4. Turn ON the main power.
5. Thevoltmetershouldbereadingapproximately
14 volts DC ±2.
6. Connect the positive lead to TP3 ±5V. The
voltmetershouldbereading+5voltsDC±0.5.
7. Turn OFF main power.
8. Connectthedisplayboardribbonconnectorto

9
5. The bath is not heating when it should be
requesting heat. Voltage measurements are
made on the POWER SUPPLY BOARD
#3176677.
a. Selectasetpointtemperatureatleast10°
above what the actual temperature is.
The bath should be requesting heat as
indicated by the heater "ON" indicator
lamp on the front panel. It should be on
continuously, not flashing.
b. Measure the voltage at U1-PIN 2 with
respect to TP2-COM. It should be no
greater than 4 VDC.
c. MeasuretheDCvoltageacrossR4. Since
the bath is requesting heat, there should
be current flowing through this resistor
making the voltage drop equal to 3 vdc
±0.5.
d. Ifthelasttwostepsarenotasstated,then
mostlikelytheCPUboardisbadanditwill
have to be replaced.
e. Switch the voltmeter to an AC volts scale
capable of reading 120 volts.
f. MeasurethevoltagebetweenU1-PIN4and
U1-PIN 6. It should be less than 1 VAC.
g. Ifitisnot,thenmostlikelytheopto-coupler
U1isbadandthePOWERSUPPLYboard
will have to be replaced. If it is, continue
on.
h. Measure the voltage directly across the
heater. Itshould belinevoltage110VAC
to120 VAC.
Open the control cover and familiarize yourself
with the POWER SUPPLY assembly #3176677.
Locate the triac (Q2), the opto-isolator (U1), the
resistor (R4), and the test point #2 (TP2-COM).
The first measurements will be DC voltage
measurements. A DC scale of at least 10 volts
should be selected.
PROBLEMS & SOLUTIONS
*********** Problem A : No Heat *************
1. Verify that the setpoint temperature is greater
than the actual water temperature.
2. VerifythattheHIGHTEMP lightis"OFF". Ifthe
light is "ON", turn the HIGH LIMIT CONTROL
fully clockwise.
3. Check temperature probe voltage reference.
These measurements are on the CPU board
#3176678.
a. Placethe negative leadofaDC voltmeter
on TP1-COM test point. Measure the
voltage at U7-pin 2. It should be
approximately14voltsDC. Now measure
the voltage at U7-Pin 6. It should be
approximately5voltsDC.Ifthe14voltsis
presentbutnotthe5volts,theCPUboard
must be replaced.
4. Check temperature probe.
a. Measure the bath water temperature and
makenoteofit.Makesureitwillnotchange
drastically during this check.
b. With a DC voltmeter, measure the supply
ofthetemperaturesensoratJ302pins1&
3. It should be approximately 5 volts. If it
is, then continue on to step C. If not, see
Step 3a.
c. Measure the output of the temperature
sensor at J302 pins 2 & 3. Pin 3 being the
reference or ground. The output
relationship of voltage to degrees
centigrade is listed in the table below.
Compare the measured voltage to the
temperatures listed to determine if the
probe is working.
pmeT C° tloV pmeT C° tloV
01V005.006V004.1
02V086.007V085.1
03V068.008V067.1
04V040.109V049.1
05V022.199V812.2

10
e. Switch the voltmeter to an AC volts scale
capable of reading 120 volts.
f. Measure the voltage between U1-PIN 4
andU1-PIN6. Itshouldbelinevoltage110
VACto120 VAC.
g. If it is not, most likely the opto-coupler U1
is bad and the POWER SUPPLY board
will have to be replaced. If it is, continue
on.
h. Measure the voltage directly across the
heater. Itshould be approximately 0 VAC.
i. If it is not, then most likely the triac Q2 is
bad,andthePOWERSUPPLYboardwill
have to be replaced.
2. CheckTemperatureProbe. ProblemA,Step4.
i. If it is not, then most likely the triac Q2 is
bad,andthePOWERSUPPLYboardwill
have to be replaced.
6. Check heater.
a. Disconnect the bath from its electrical
supply.
b. Isolate the heater from any circuitry by
disconnecting one of the heater leads.
c. Using an ohmmeter, check the heater
resistance. Appropriateheaterresistance
values are listed below:
If the resistance reads 0 or infinity, then
replace the heater.
d. Check the resistance between the heater
leads and ground (green wire). If the
resistance reads 0 ohms, replace the
heater.
********* Problem B: Constant Heat *********
1. Bath is heating when it is not requesting heat.
a. Selectasetpoint temperatureatleast10°
below the actual temperature. The bath
shouldnotberequestingheatasindicated
bythe HEATER ON indicator lamp onthe
front panel. It should NOT be on
continuously or even flashing.
b. Measure the voltage at U1-PIN 2 with
respecttoTP2-COM. Itshouldbenoless
than 4 VDC.
c. Measure the DC voltage across R4. The
voltageshouldbeapproximatelyzerovolts.
d. If the last two steps are NOT as stated,
thenmostlikelytheCPUboardisbadand
it will have to be replaced, otherwise
continue on.
*** Problem C: Unstable Temperature ***
Control or Display
1. Use gable cover provided to improve
temperature control.
2. If control is stable but not at desired
temperature, then check temperature
calibration. Readjust if necessary.
3. Check Temperature Probe, Problem A, Step 4.
TLOV021TLOV032
SMHO51SMHO06

11
** ProblemD: Display Reads NNNNor UUUU **
The control boards have the ability to detect an
OPEN or SHORTED temperature sensor. These
twoconditionsareshownonthedisplayasfollows:
DISPLAY CONDITION
Before coming to the conclusion that the probe is
badwhenoneofthesedisplaysappear,checkthe
connection of the probe to the circuit board for
polarityandalignment.
* Problem E: Display Reads all Eights (8888) *
1. The most common problem cause of this
problem is the failure of the driver integrated
circuit on the DISPLAY/KEYBOARD board
(#3176679). Replace it.
*** Problem F: Pump Does Not Circulate ***
Water
1. Verify that the water level is above both the
pump inlet and outlet.
2. If the pump is not running, verify that power is
appliedtothe bath. If powerispresent, check
wiring of pump to power switch. If wiring is
correct, replace the pump.
3. If pump is running but water is not circulating,
openthecontrolpanelandgentlysqueezethe
longpieceofrubbertubingafewtimestohelp
remove any air trapped within the pumping
system.
4. Ifwaterisstill not circulating,checkforforeign
matter in the pump inlet fitting.
SHORT CIRCUIT
OPENCIRCUIT

12
PARTS REPLACEMENT
NOTE: For easiest access to the control housing, place bath on the edge of a bench or table.
Remove four screws on upper side of control housing and carefully lower hinged control panel
to the vertical position.
Circulating Pump
Replacement 1. Drain water from bath.
2. Remove the two pump leads attached to power switch and
green wire from pump to ground lug.
3. Loosen the two visible hose clamps with a screwdriver and
remove tubing from pump.
4. Disconnect pump from pump bracket by removing two
screws and remove pump from bath.
5. Reverse above procedure to install new circulating pump.
1. Drain water from bath.
2. Remove diffuser pan from bath.
3. Remove connector J302 from CPU board.
4. Remove temperature sensor fitting from inside bath pan.
- Hold small nut on fitting firmly with a wrench.
- Remove large fitting piece with another wrench.
5. Remove rubber grommet from temperature sensor.
6. Carefully slide sensor through the control housing and
remove.
7. Reverse above procedure to install new temperature
sensor.
8. Recalibrate new temperature sensor. See Temperature
Calibration on page 15.
Replace Temperature
Sensor
PARTS REPLACEMENT
Before removing any parts for replacement, verify
part in question by following the instructions listed
inthe troubleshooting guide.
Refer to Parts Replacement Table below for
appropriate replacement procedures. Failure to
follow parts replacement procedures may cause
damage to the bath.
WARNING
BEFORE REPLACING ANY PART, TURN
POWER SWITCH TO OFF, THEN UNPLUG
THE UNIT FROM ITS POWER SOURCE.
SERVICE SHOULD BE PERFORMED BY A
QUALIFIED TECHNICIAN.
CAUTION
WHEN REPLACING TEMPERATURE SENSOR,
HEATER OR CIRCULATING PUMP, MAKE
SUREALL SEALS ARE WATERTIGHT BEFORE
APPLYING ELECTRICAL POWER.

13
Replace Heater 1. Frominsidecontrol housing, remove2 nutsand disconnect
wiresfromheaterleads.
2. Removetwohexnuts from heaterends usinga 13/16"
socketandremoveheater.
3. Reverseaboveproceduretoinstallnewheater.
Replace "HI LIMIT" 1. Removefourleadsfromthermostatterminals.
Thermostat 2. Removetwoscrewsfromthermostatbracketandremove
bracket.
3. Carefully tilt bath on its side.
4. Removeeightscrewsfrombottomplateandremoveplate.
5. Removeinsulationfrombottomofpanandbetweenpan
andcontrolpanelwall.
6. Loosentwo nuts from thermostat bulb bracket.
7. Carefullyremovethermostatfromcontrolhousingbysliding
bulbthroughholein control panelwall.
8. ReverseaboveproceduretoinstallnewHiLimitthermostat.
Use extreme care when installing new thermostat. A sharp
bend in the thermostat capillary will crimp off flow of
hydraulicfluid.
Replace Power Supply 1. RemoveconnectorsJ101,J102,J103,andJ105fromboard.
Board UseextracarewhenremovingJ102soasnottobend
connectorpins.
2. Removefivenutsfromboardandthenremoveit.
3. Reverseaboveproceduretoinstallnewpowersupplyboard.
Replace CPU or 1. RemoveconnectorsJ302andJ303fromCPUboard.
Display/Keyboard
Board 2. RemoveconnectorJ102frompowersupplyboard. Use
extremecarewhenremoving J102soasnot tobend
connectorpins.
3. RemovefournutsfromCPUboardandremoveCPUboard
andKeyboard/Displayboard.
4. RemoveJ201fromCPUboard. Useextremecarewhen
removingJ301soas not tobendconnector pins. Remove
board.
5. Reverseaboveproceduretoinstallnewboard.
PARTS REPLACEMENT (CONT'D)
See note on the
following page **

14
Replace CPU or
Display/Keyboard Board
See note below **
* The low and high end of the sensor input is calibrated at the factory. Field calibration of the sensor may be
performed using the following technique: Enter the configuration routine and press the top left switch until a
little "c" (Item H) is displayed. Add water that is around 10°C to the bath completely covering the sensor.
Insert a calibrated thermometer. After the thermometer stabilizes, match the display setting to the thermom-
eter reading by pressing the "UP" or "DOWN" push button switch. Press the top left switch. The readout will
now display a big "C" (Item I). Remove water from the bath and add hot water of about 70 - 80°C. After the
unit stabilizes, match readout display to temperature on thermometer and press the top left switch. Calibra-
tion is now complete.
**Note:
When replacing CPU printed circuit board reprogramming may be necessary.
Follow thoroughly instructions provided with the replacement circuit board.
PARTS REPLACEMENT (CONT'D)
6. The software must be configured to match the Bath model.
To enter configuration mode, press the upper left push-button
switch while applying power. The upper left switch is labeled
"Set Point." This switch is used to enter configuration
codesandstepsthroughthedifferentlevelsofconfigurations.
When a triangle is shown in the chart, the push-button is to be
depressedonceforeachsymbol.
Immediatelyfollowingpowerupwiththeswitchdepressed,
the readout will display a 3-digit number. This is the software
revision. Thereadout will then begin to do a self-test of
digits. Press the "Set Point" button once. The readout will display
0000. Follow the listing below to complete the
configuration.
A. Enter37usingup/downarrows. Press "Set Point"
B. Enter31usingup/downarrows. Press "Set Point"
C. Enter2.0usingup/downarrows. Press "Set Point"
D. Enter500usingup/downarrows. Press "Set Point"
E. Enter1usingup/downarrows. Press "Set Point"
F. Display Not Used. Press "Set Point"
G. Display Not Used. Press "Set Point"
H. LOWTEMPCALIBRATION*
LITTLEc. FactorySetting. Press "Set Point"
I. HITEMPCALIBRATION
BIG C. Factory Setting. Press "Set Point"
Configuration is now complete

15
TEMPERATURE CALIBRATION
The following instructions provide a step-by-step
procedure for temperature calibration. Do not
deviatefromtheprocedureor thecalibrationof
your bath may be inaccurate.
CAUTION
THIS PROCEDURE SHOULD ONLY BE
PERFORMED AFTER INSTALLING A NEW
TEMPERATURE PROBE INTO THE BATH.
1. Connect the temperature probe connector to
J302 on CPU board.
2. Turn Power switch to the OFF position.
3. PressandholdtheSETPOINTkeywhileturning
Power ON.
4. TheunitwillnowcyclethroughanLEDdisplay
test. Press SETPOINT to end test.
5. Thedisplaywillnowread0000. PressUPuntil
display reads 0012. Press SETPOINT.
NOTE:
IF A VALUE OTHER THAN 0012 IS DISPLAYED
AND SETPOINT IS PRESSED, THE UNIT WILL
RETURNTONORMALOPERATINGMODEAND
DISPLAY WILL SHOW ACTUAL BATH
TEMPERATURE.
6. The unit is now in Calibration mode. Raw
count value appears. Hit setpoint.
7. ThedisplaywillnowshowcXX.X(XX.Xisthe
actual bath temperature) - this is Low
Temperature Calibration.
8. Placethetemperatureprobeandacalibrated
referencethermometerintoanicebath.Press
UPor DOWNuntilthedisplayvaluematches
thereferencethermometer.PressSETPOINT
to store the new low temperature calibration
value.
9. ThedisplaywillnowshowCXX.X-thisisHigh
Temperature Calibration (XX.X is the actual
bath temperature).
10. Placethetemperatureprobeandacalibrated
referencethermometerintoasteamingwater
bath. Press UP or DOWN until the display
value matches the reference thermometer.
Press SETPOINT to store the new high
temperature calibration value.
NOTE
PRESSING OFFSET AT ANY TIME DURING
THE CALIBRATION PROCESS WILL RETURN
UNIT TO NORMAL OPERATION MODE AND
DISPLAY WILL SHOW ACTUAL BATH
TEMPERATURE.