Thermo Electron 260 Supplement

Installation/Service Manual
Circulating Water Baths
Models 260 (2864/2865), 265 (2866/2867), 270 (2868/2869)
Thermo Electron Corporation
Millcreek Road, Box 649
Marietta, Ohio 45750
USA
Phone: [phone]
Toll Free: 800-848-3080
FAX: [phone]
Manual P/N 3177890
Rev. E Dated 18April, 2005
Hig h Te mp .
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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. THERMO ELECTRON CORPORATION MAKES NO REPRESENTATIONS OR
WARRANTIES WITH RESPECT TO THIS MANUAL. IN NO EVENT SHALL THERMO BE
LIABLEFORANYDAMAGES,DIRECTORINCIDENTAL,ARISINGOUTOFORRELATEDTO
THEUSEOFTHISMANUAL.
Forrepairinformationorreplacementpartsassistancefromthemanufacturer,callTechnicalServicesusingourtoll
freetelephonenumber.
888-213-1790
(FAX)740-373-4189

INDEX DATE NOTES
REVISION STATUS
Initial releaseA
AMENDED PAGES
6/99
Updatepumpassemblykitnumbers
(new pumps)
B 5/00 16
C NOV01 Add caution "acidic & caustic
substance....."
6
D
E
APR02
APR05
Addinletscreeninfo,correct wirecolor
newmanual#,manufacturelocation
5,8,27
36100125 (34002503)

Contents
INTRODUCTION.................................................................................................................. 1
UNPACKING AND DAMAGE .............................................................................................. 1
GENERAL INFORMATION.................................................................................................. 2
PERFORMANCE................................................................................................................. 2
INSTALLATION ................................................................................................................... 2
WATER LEVEL REGULATOR ........................................................................................... 3
EXPLANATION OF CONTROLS ........................................................................................ 6
OPERATION ........................................................................................................................ 7
MAINTENANCE................................................................................................................... 8
TROUBLESHOOTING ........................................................................................................ 8
PARTS REPLACEMENT .................................................................................................. 13
TEMPERATURE CALIBRATION ...................................................................................... 16
REPLACEMENT PARTS LIST ......................................................................................... 17
ASSEMBLY & SCHEMATIC DWGS ................................................................................. 19
WARRANTY ...................................................................................................................... 28

1
UNPACKING AND DAMAGE
Save all packing material until unit is put into
service. This merchandise was carefully packed
and thoroughly inspected before leaving our
factory.
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
evidenceof loss ordamage onthe freight 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
lossordamage meanslossor 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
aclaimwiththecarriersincethedamageisthe
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—FOR ANYREASON—RETURN
THIS 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
Thermoandacompleteunderstandingofthisunit
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. Theunitshouldbeusedfor
itsintendedapplication;alterationsormodifications
will VOID THE WARRANTY.
WARNING
AS A ROUTINE LABORATORY PRECAUTION,
ALWAYS WEAR SAFETY GLASSES WHEN
WORKING WITH THIS APPARATUS.
Thisproductisnotintended,norcanitbeused,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
Thefollowingtableidentifiesthespecificationsfor
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.
Electrical Connections -
IMPORTANT
For personal safety, this apparatus must
beproperlygrounded.
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
temperature control. Use of the gable cover
providedisrequiredtomaintainoptimaltemperature
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 115-volt units.
4.02 Performance Data
With Cover
Model #260 Model #265 Model #270
Uniformity 37°C ± .05 ± .05°C ± .05
Sensitivity 37°C ± .05 ± .05°C ± .05
Table 1
Listing of Models Included In This Manual
Category
Number Model Volts Hertz Watts Amps
3166680 #260 120 50/60 1000 8.3
3166682 230 50/60 1000 4.3
3166684 #265 120 50/60 1550 12.9
3166685 230 50/60 1550 6.7
3166681 #270 120 50/60 1550 12.9
3166683 230 50/60 1550 6.7

3
WATER LEVEL REGULATOR
(OPTIONAL)
INSTALLATION INSTRUCTIONS - Use the
following steps along with Fig. 1 & 2 shown on the
following page.
1. Turn off unit, disconnect power & drain water
from the bath.
2. Unscrew drain plug from side of bath body.
3. Replacewithelbowconnector(shippedloose).
NOTE
TOINSUREGOODSEAL,WRAPTHREADSWITH
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
fall within the following range: MIN is approx.
15 PSI, MAX is approx 75 PSI)
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.
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
DISTILLEDWATER (50KOHMS TO1-M) IN THE
BATH. DO NOT USE DEIONIZED WATER,
OVERTIMEITBECOMESCORROSIVEANDWILL
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
OXYGEN. THE RESULTING ELECTROLYTIC
ACTION WILL PIT OR ERODE THE STAINLESS
STEEL.

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
SILICON HOSE
WATERBATH
PAN
INLET NUT
TUBE ADAPTER
SCREEN ASSEMBLY
(FINGER TIGHTEN ONLY)
D
IRECTION OF WATER FLOW
NOTE:INLET IS THE LOWER O
F
THE 2 PORTS
INLET SCREEN ASSEMBLY
(OPTIONAL)
Anoptionalinletscreen assembly ispackagedwith
each unit. If used, this screen will filter foreign
materials (i.e. pieces of paper) from being sucked
through the pump. To install the screen assembly,
refer to the diagram below.
NOTE:
IF USED, THE SCREEN ASSEMBLY MUST
BE INSPECTED DAILY. REMOVE ANY
DEBRIS FOUND ON THE SCREEN.

6
Press ENTERto store the new value.
Press Set Point.
θ
Press or until value is displayed.
To adjusttemperature:
π
ENTER
Set Point
Heater On
Offset
Bath Temp., °C
Set Point
Actual
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
cornerof thebath. The high limitis anadjustable
control used to prevent thermal runaway in the
eventthattheprimarycontrolfails.Afteryouhave
stabilized the bath temperature, use a standard
screwdriver to adjust the potentiometer. When
delivered, the Hi-Limit is turned fully clockwise
(highest setting). In this position the Hi-imit light
will be OFF. Turn the potentiometer counter-
clockwise until the Hi-Limit light is ON, and
thenadjust
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.

7
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
NOTBEHIGHERTHAN1INCHFROMTHETOP
OF THE BATH PAN.
To conserve energy, reduce evaporation and
increase temperature control accuracy, use the
gablecover provided. Donot usealuminum foil as
a cover, as it may cause corrosion due to an
electrochemical reaction.
1. Add distilled water to bath. Use water levels
as instructed above.
2. Power up: Depress the power switch located
atthelowerrighthandcornerofthe bath. 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. If ENTER is not pressed, new value will
not 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
EXCERCISED 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
UPSIDEDOWNWHEN REMOVEDTOMAINTAIN
A DRY WORK AREA.
.

8
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.
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
Precision Scientific (P/N 51200912).
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 OROTHER ADEQUATEEYE
PROTECTION. ONLY WORK IN AREAS WITH
ADEQUATEVENTILATION.
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.
Screenassemblyoption:Ifthisoptionisinstalled,
inspect daily and remove any debris from the
screen.
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.

9
8. Connectthedisplayboardribbonconnectorto
the power supply board at J102 and then
repeat steps 3 thru 6. Do not connect the
connectortotheCPUboardatthistime. Ifthe
above voltages are not measured again, the
display board has a bad component which is
loadingdownthevoltages. Ifthevoltagesare
still present, continue on to step 9.
9. Connectthedisplayboardribbonconnectorto
theCPUboardJ310andrepeatsteps3thru6.
Iftheabovevoltagesarenotmeasuredagain,
theCPUboardhasabadcomponentwhichis
loading down the voltages. This board will
have to be replaced.
GENERAL INFORMATION: The POWER
SUPPLY PCB ASSEMBLY #34372501 has the
triac (solid state AC voltage switch) on it which
suppliesthepowertotheheater. Thistriacis"told"
tooperate, whenneed 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 reason beingthey areunder
higher operating stress than other components.
If the bath starts experiencing temperature
problems 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
• AC Voltmeter
• 5VDC Power Supply
When changing circuit boards, please use
CAUTION when re-installing the flat cable
connectors that come from the display board.
Make sure the pins are NOT bent or broken.
Boards that are otherwise fine will not operate
correctly if these pins have been abused because
they will not 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 #34372501. 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. SelectaVDC of 20. 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.

10
5. The bath is not heating when it should be
requesting heat. Voltage measurements are
made on the POWER SUPPLY BOARD
#3166924.
a. Select a setpoint temperature at least
10°abovewhattheactual temperatureis.
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. Measure the voltage between U1-PIN 4
and 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. It should be line voltage 110VAC
to120 VAC.
Open the control cover and familiarize yourself
with the POWER SUPPLY assembly #3166924.
Locate the triac (Q2), the opto-isolater (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. Verify that the HIGH TEMP light is "OFF". If
the light is "ON", turn the HIGH LIMIT
CONTROL fully clockwise.
3. Check temperature probe voltage reference.
These measurements are on the CPU board
#3167119.
a. Placethe negative leadof aDCvoltmeter
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
make note of it. Make sure it will not
change 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.
Temp
Degrees C Volt Temp Degrees C Volt
10 0.500V 60 1.400V
20 0.680V 70 1.580V
30 0.860V 80 1.760V
40 1.040V 90 1.940V
50 1.220V 99 2.218V

11
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.
e. Switch the voltmeter to an AC volts scale
capable of reading 120 volts.
f. Measure the voltage between U1-PIN 4
and U1-PIN 6. It should be line voltage
110 VAC to 120 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. It should be approximately 0 VAC.
i. If it is not, then most likely the triac Q2 is
bad,and the POWER SUPPLY board will
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. Selectasetpointtemperatureatleast10°
below the actual temperature. The bath
shouldnotberequestingheatasindicated
bytheHEATERONindicator 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.
*** 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. Re-adjust if necessary.
3. CheckTemperatureProbe,ProblemA, Step4.
115 VOLT 230 VOLT
Model 260 15 OHMS 60 OHMS
Model 265 10 OHMS 40 OHMS
Model 270 10 OHMS 40 OHMS

12
** ProblemD:DisplayReadsNNNNorUUUU **
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
polarity and alignment.
* 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
appliedto thebath. Ifpower ispresent, 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
longpieceofrubber tubingafewtimesto help
remove any air trapped within the pumping
system.
4. Ifwaterisstillnotcirculating,checkforforeign
matter in the pump inlet fitting.
SHORT CIRCUIT
OPEN CIRCUIT

13
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
in the 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
BEFOREREPLACINGANYPART,TURNPOWER
SWITCH TO OFF, THEN UNPLUG THE UNIT
FROM ITS POWER SOURCE. SERVICE
SHOULD BE PERFORMED BY A QUALIFIED
TECHNICIAN.
CAUTION
WHEN REPLACING TEMPERATURE SENSOR,
HEATERORCIRCULATINGPUMP,MAKESURE
ALL SEALS ARE WATERTIGHT BEFORE
APPLYING ELECTRICAL POWER.

14
Replace Heater 1. From inside control housing, remove 2 nuts and disconnect
wires from heater leads.
2. Remove two hex nuts from heater ends using a 13/16"
socket and remove heater.
3. Reverse above procedure to install new heater.
Replace "HI LIMIT" 1. Remove four leads from thermostat terminals.
Thermostat 2. Remove two screws from thermostat bracket and remove
bracket.
3. Carefully tilt bath on its side.
4. Remove eight screws from bottom plate and remove plate.
5. Remove insulation from bottom of pan and between pan
and control panel wall.
6. Loosen two nuts from thermostat bulb bracket.
7. Carefully remove thermostat from control housing by sliding
bulb through hole in control panel wall.
8. Reverse above procedure to install new Hi Limit thermostat.
Use extreme care when installing new thermostat. A sharp
bend in the thermostat capillary will crimp off flow of
hydraulic fluid.
Replace Power Supply 1. Remove connectors J101, J102, J103, and J105 from board.
Board Use extra care when removing J102 so as not to bend
connector pins.
2. Remove five nuts from board and then remove it.
3. Reverse above procedure to install new power supply board.
Replace CPU or 1. Remove connectors J302 and J303 from CPU board.
Display/Keyboard
Board 2. Remove connector J102 from power supply board. Use
extreme care when removing J102 so as not to bend
connector pins.
3. Remove four nuts from CPU board and remove CPU board
and Keyboard/Display board.
4. Remove J201 from CPU board. Use extreme care when
removing J301 so as not to bend connector pins. Remove
board.
5. Reverse above procedure to install new board.
PARTS REPLACEMENT (CONT'D)
See note on the
following page **

15
Replace CPU or
Display/Keyboard Board
See note below **
* Calibration of the low and high end of the sensor input is done 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 thermometer 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. Calibration 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 pushbutton
switch while applying power. The upper left switch is labeled
"Set Point." This switch is used to enter configuration
codes and steps through the different levels of configurations.
When a triangle is shown in the chart, the pushbutton is to be
depressed once for each symbol.
Immediately following power up with the switch depressed,
the readout will display a 3-digit number. This is the software
revision. The readout 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. Enter 37 using up/down arrows. Press "Set Point"
B. Enter 31 using up/down arrows. Press "Set Point"
C. Enter 2.0 using up/down arrows. Press "Set Point"
D. Enter 500 using up/down arrows. Press "Set Point"
E. Enter 1 using up/down arrows. Press "Set Point"
F. Display Not Used. Press "Set Point"
G. Display Not Used. Press "Set Point"
H. LOW TEMP CALIBRATION*
LITTLE c. Factory Setting. Press "Set Point"
I. HI TEMP CALIBRATION
BIG C. Factory Setting. Press "Set Point"
Configuration is now complete