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GALAXY R SERVICE MANUAL CONTENTS:

1. Notable Design Changes 2 2. General Description 3 3. Engineering Menu 4 4. Heating and Temperature Control System 8 5. Calibration Thermometer Placement 12 6. CO2 System 13 7. CO2 Sensor Replacement 14 8. CO2 Sensor Cleaning Procedure 14 9. Temperature Sensor Fault Diagnosis 15 10. Chamber Temperature Sensor Replacement 16 11. Top Cover Securing Screw Location 17 12. EPROM Replacement Flow Chart 18 13. EPROM Replacement Procedure 19 14. Membrane Keypad / Display Replacement 20 15. Membrane Keypad Testing 22 16. R-T Curve Matched Thermistor Graph 23 17. Temperature Recovery Graphs 24 18. Incubator Wiring Schematic 28 19. Incubator Schematic Display Wiring 29 20. Cross-section through CO2 Sensor 30 21. CO2 Detector Assembly 31 22. CO2 Sensor Connections 32 23. CO2 Flow Path Schematic 34 24. Control PCB Fault Diagnosis 35 25. Molex IDC Connector Assembly 38 26. Lost User Access Code Recovery 39 27. Gas & Gas Regulator Specifications 40 28. Typical Automatic Gas Changeover Unit Installation 41 29. Chamber Seal Removal & Replacement 43 30. 3 or 6 Door Frame Replacement 44 31. Cooled Galaxy R 47 32. Cross-section Through Cooled Galaxy R 51 33. V-ring Seal Adjustment on Cooled Galaxy R 52 34. Cooled Galaxy R Wiring Schematic 53 35. 110V High Temperature Galaxy R Description 54 36. 110V High Temperature Galaxy R Schematic 55 37. Oxygen Control General Description 56 38. Oxygen Control Schematic All Variants 58

Issue 8 17/05/05

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1. Notable Design Changes

Date:- Applies To:- Change:- Reason:- Jan 2001 All Galaxy R Hermetically sealed / sapphire-

windowed detector introduced Eliminates moisture ingress

Nov 2001 3 & 6 Door R Knurled knob closure introduced Allows use of standard magnetic catch

Nov 2001 110V Hi Temp R Option introduced Customer request Apr 2002 All Galaxy R Mains fuse changed from 1.6 or

2A, to 4A Stock consolidation

May 2002 3 & 6 Door R Knurled knob superceded Cost reduction 2002 Cooled R Colour-coded 18AWG wire

introduced for TEC wiring Ease of manufacture / servicing

Apr 2002 Cooled R Additional protection fuse added in series with the primary of the toroidal transformer.

Prevents risk of fire if transformer secondary is short-circuited.

Sept 2002 All Galaxy R (4161 onwards)

ASF Thomas A/z Pump replaced by KNF Neuberger Pump.

Cost reduction

Feb 2003 All Galaxy R / S Humidity Tray design changed Self-positioning under Deflector

Sept 2003 Cooled Galaxy R (5721 onwards)

Use 520mm Long runners for Humidity Tray

New Tray fouls cooled runners

Mar 2004 All Galaxy R Wire Racking System Introduced Easier Cleaning

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2. General Description

The Galaxy R control system is a completely new design including the CO2 sensor.

Temperatures are measured by four curve-matched thermistors of the same type and in the same way as the previous Galaxy series. These sensors have a similar control function to the 170-001 PT100 incubator sensors, but temperature calibration is carried out in software by offsetting the normal value to create a correct temperature.

The CO2 sensor feeds the signal from the CO2 detector directly to the A to D converter on the control PCB where it is converted into a digital count. Fully automatic, auto zeroing is carried out by a small pump which pumps HEPA-filtered atmosphere into the measuring chamber of the sensor to allow the sensor to be regularly re-referenced to atmosphere without user intervention. There is also a CO2 pressure detector, which monitors the CO2 supply and the correct operation of the CO2 valve.

The four elements of the control system are as follows:

1. Control PCB carries out all control functions, analyses input sensor signals and drives the graphics display.

2. The CO2 sensor with auto zero pump and pressure detector (mounted on the control pcb).

3. Four curve-matched thermistors measure the following temperatures: Chamber, Chamber Element, Door and Door Element.

4. Graphics display with fluorescent backlighting and inverter.

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3. Engineering Menu

3.1 All calibration points and other adjustments are contained within the Engineering Mode, also the control of options when fitted can be activated, therefore one EPROM covers all incubator variants.

3.2 The EPROM user firmware version is accessed from the user screen and starts AAxxxxxxxxxxxx. The User Manual and HELP file relate to this issue number. The first issue being AA 1908991337.

3.3 The EPROM engineering firmware revision issue is accessed from the Incubator Type Change screen in the engineering mode and starts BAxxxxxxxxxxxx. This revision being continuously updated when new options and option combinations are added. The first issue being BA 2308991524.

3.4 To access the engineering mode, press DIAG and ENG, enter the access code of 1973 and press ENTER.

3.5 The menu is as follows:

a) RESET TO DEFAULTS 1. Do not press YES as this cancels all the factory calibration points.

2. Press TEXT to clear the Datalogger Alarm Events screen.

b) INCUBATOR TYPE CHANGE

This screen is factory set with the options relevant to the incubator. It should not be altered unless for instance, a BMS relay is retro-fitted.

The CO2 range of either 0-10% or 0-20% relates to the sensor type fitted and should not be changed without changing the CO2 sensor.

c) CO2 BULB

This screen allows the IR bulb light intensity to be adjusted. It is factory set to 221 and should not be altered under normal circumstances.

d) CO2 AUTOZERO

This screen displays information on auto zeroing. For a detailed description see CO2 Calibration on page 13.

e) CO2 AUTO-GAIN

This screen displays information on auto-gain calibration of the CO2 level. For a detailed description see CO2 Calibration on page 13.

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f) AD CALIBRATION

This screen contains factory testing of the calibration of the 8 channels of the A to D converter and should not be adjusted.

g) TP 29 OUTPUT SELECT

This screen is for factory testing of various PCB functions and has no function in servicing.

h) COOL SPOT WARMER

This screen is for development purposes and has no function in servicing.

i) ENGINEERING DIAGNOSTICS

This screen gives information related to oxygen control. Its function is described in the oxygen control section.

j) USER ACCESS CODE

This screen displays the User Access Code. If one has been programmed if there is not one programmed it shows 0000.

k) SYSTEM

This screen contains the following:

1. Temperature Sensor Offset Adjust. This screen allows individual temperature sensors to be calibrated by giving them a permanent +ve or ve offset.

2. Temperature Chamber Control Points. This screen contains the heating system control points for the chamber heating system.

3. Temperature Door Control Points. As above, but for the outer door / fascia heating system. (See Chapter 4 for detailed information on 1 3 above)

4. CO2 Valve Control. This screen allows the CO2 Pulse Point and the CO2 Delay Time to be adjusted. The CO2 Pulse Point is fixed as defined in the table below (for a 0 10% CO2 Sensor), but can be further adjusted by changing the CO2 Control Point.

Programmed CO2 Level: Set Point less:

0.0% to 0.8% 0% 0.9% to 1% -0.8% 1.1% to 2% -1.0% 2.1% to 3% -1.1% 3.1% to 4% -1.2% 4.1% to 5% -1.3%

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5.1% to 6% -1.3% 6.1% to 7% -1.4% 7.1% to 8% -1.5% 8.1% to 9% -1.6% 9.1% to 10% -1.7%

If a 0 20% CO2 sensor is fitted to the incubator, the following additional points apply: 10.1% to 20% -1.7%

The CO2 Pulse Point is the CO2 measurement point at which the valve switches from being on continuously to pulsing on / off' as it approaches set point. Note: the final ' CO2 Pulse Point' is derived by taking the table figure and adding the CO2 Control Point value to it.

Eg: At a setpoint of 5.0% CO2 the table figure is -1.3%. with an eg: CO2 Control Point of -0.2% the CO2 Pulse Point will be 5 -1.3 -0.2 = 3.5%

The ' CO2 Control Point' is adjustable from 0% to -2.5% co2 in steps of 0.1%

CO2 Delay Time is an adjustable delay between the valve closing after having been on continuously (passing through the CO2 Pulse Point) and beginning to pulse. This delay is incorporated to allow the user control over the amount of time allowed for chamber gas mixing to occur. Too short a delay may lead to CO2 overshoot. NB: this delay only occurs once after any of the following events:- startup, decontamination complete, door close, autozero completion, or N2 valve opening during 0.1% O2 control (0.1-1 & 0.1-19% O2 models only)

5. Clock Calibration. This screen allows the clock to be accurately calibrated.

6. ROM Checksum. This provides important diagnostic information to help solve intermittent / problematic faults. See page 36 for a full explanation.

7. Display Options. Changes display appearance. The display will default to white text on a blue background, but can be reversed to have blue text on a white background. To do this:-

Ensure the display is showing the SYSTEM menu, and DISPLAY OPTIONS has been selected. Then:- a) Press ENTER. b) Select DISPLAY OPTIONS. c) Press ENTER. d) Select COLOUR SCHEME. e) Use the & keys to toggle between NORMAL (white text on blue

background) and REVERSE (blue text on white background). f) Press ENTER to select your preferred display colour scheme. g) Press EXIT 4 times to return to the main screen. If the display appears blank, very feint or all white, slowly adjust VR1 on the control PCB to adjust the contrast of the LCD.

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8. Serial Number. This is used to ensure the correct CO2 curve and bulb - flashing rate are applied to the CO2 sensor. Incubators after serial No. 2557 (inclusive) are fitted with a new type of CO2 detector having a sapphire window. This has slightly different characteristics which affect calibration. This menu option allows the software to select the correct CO2 curve and bulb-flashing rate for either new or old sensors based on the serial number. If a replacement control PCB, or a new EPROM (issue BA3110010851 or later) is being fitted to an old board, the incubator will prompt for the incubators serial number. If a serial number prior to 2557 is entered the incubator will ask if a new CO2 sensor is also being fitted. Selecting YES applies the sapphire-windowed detector characteristics. Selecting NO applies the mica-windowed detector characteristics. The bulb-flashing rate can also be manually changed at any time from the 'CO2 BULB' menu. The 'DEF 1' button applies the old (mica window) type bulb-flash rate settings, and the 'DEF 2' button applies the new (sapphire window) type bulb-flash rate settings. The CO2 curve calculation can be switched manually. To do this, from the ENG menu, select 'INCUBATOR TYPE CHANGE'. From this select CO2. There are four possible options: MKI 0-10%, MKI 0-20%, MKII 0-10%, MKII 0-20%. Use the & keys to scroll through the options, and press ENTER to apply the selected CO2 sensor curve.

NB: MK1 sensor types must be used in conjunction with 'DEF 1' bulb-flashing settings and MK2 sensor types must be used in conjunction with 'DEF 2' bulb-flashing settings respectively, or incorrect measurements will result. There is a flow chart on page 18 explaining the process graphically.

9. O2 Calibration (Where O2 option is fitted). This screen contains the zero offset and O2 reference factor for calibrating the oxygen sensor. (See oxygen control section).

10. RH Display Calibration (Where RH Display Option is fitted). This screen allows the RH sensor to be calibrated accurately.

11. RH Display Settings (Where RH Display Option is fitted). This screen allows the RH sensor Alarm Arm Point and Delay Time to be adjusted. The default Alarm Arm Point is 88% Rh, but can be adjusted anywhere between 20 88% Rh. The default Delay Time is 60 minutes, but it can be adjusted anywhere in the range 60 180 minutes.

The Delay Time is the time at which the alarm system will re-asses the Rh level, If the level does not reach or exceed the arm point before this.

Eg - Delay Time is set to 60 minutes:

If 60 minutes has passed and Rh level has not reached or exceeded the arm point, but has shown a rise in last 5 minutes, then the system will wait a further 60 minutes and begin again. If the Rh level does not show a rise in the last 5 minutes an alarm occurs. If an alarm occurs, it will subsequently re-arm only if arm point has been reached or exceeded.

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4. Heating and Temperature Control Systems

4.1 Guide to Calibration

1. Place a sensor centrally on the top shelf of the chamber and assuming that the incubator has been running and the doors are opened for as short a time as possible, the temperature should stabilise in about 30 minutes. See page 12 for a sketch of the recommended set up.

2. Go into Engineering Mode and select SYSTEM, then TEMPERATURE SENSOR OFFSET ADJUST and adjust the offset by the difference between the actual and measured value using the & and ENTER keys.

4.2 Guide to Door Offset

1. If condensation appears on the inner door, is heavy on the seal, or appears towards the top of the chamber walls, it is possible to warm the door up to reduce or eliminate it. It is important to ensure the humidity tray is directly below the deflector plate and that there is no spillage on the bottom of the chamber.

2. If the programmed temperature is close to ambient and the chamber temperature is tending to overshoot set point, it is possible to cool the door and eliminate the overshoot. This is also useful when running heat-generating apparatus inside the chamber which may cause the chamber temperature to overshoot.

3. To make the door warmer, select SYSTEM, TEMPERATURE SENSOR OFFSET ADJUST and DOOR make the offset initially -0.3C. This will cause the door to warm up. The door element must also be adjusted. Select DOOR ELEMENT and reduce offset as necessary to ensure that the door warms up to 37.0C.

4. To make the door cooler, carry out the reverse process.

5. If the door offset is adjusted by more than 0.5C it may be necessary to recheck the chamber temperature as described in 4.1 Guide to Calibration.

4.3 Heating System There are 2 independent heating systems, one for the chamber and another for the outer door and front facia. Each system has an independent electronic switch on the main control PCB. Both systems are heated by mains (230 or 110VAC) voltage.

The chamber heating system comprises around 45 metres of heating element, wrapped to a specific pattern on five sides of the chamber. The pattern is designed to ensure that the chamber is at an even temperature throughout with no condensation on the walls.

The door heating system comprises 2 elements in series, one inside the door and the other inside the front fascia of the main body of the incubator. The temperature of the door system is regulated such that there is sufficient heat to stop condensation on the glass door without starting to drive the chamber temperature up. Each heating system is protected by a 70C (150C on High Temp models) trip switch, which if tripped, has to be manually reset; see Chapter 4.8, page 11

4.4 Fault Finding (see drawing BTC21-811, pages 28 & 29)

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4.5 Refer to the drawing on page 17. To remove the top cover take out the 2 screws above the outer door, slide forward about 5cm to disengage it from the rear location and then lift it up, taking care not to break the Earth bonding wire.

1. Continuity of the elements can be checked by testing with one probe at the control PCB and the other at the mains distribution terminal.

N.B. An open circuit reading on the chamber or door may mean that the over-temperature trip is activated and requires testing / resetting.

It is possible to replace the door if the element is faulty but the fascia and chamber elements can only be factory repaired.

2. The four thermistors can be checked using an ohm meter. They should be around 30k ohms at room temperature and 17 k ohms at 37C. (Refer to graph on pg 23).

3. If either of the four thermistors resistance values falls outside the measuring limits an alarm is signalled and TEMP SENSOR FAILURE is displayed on the screen. If this happens the over-temperature relay is tripped to ensure that under no circumstances will the chamber be overheated. See also Chapter 4, page 11.

4.6 Temperature Control

1. The chamber temperature is measured by a sensor in the back wall of the chamber, the chamber element sensor is attached to the heating element. Both sensors can be accessed by removing the rear cover. The door sensors cannot be accessed - if a failure occurs it is necessary to change the door.

2. The chamber and door heating systems are factory calibrated and balanced to give even temperatures within the chamber and minimal vertical and horizontal gradients whilst at the same time minimising condensation on the inner door.

If the door temperature is increased, any tendency for condensation on the glass door is eliminated, but less heat needs to be input to the chamber by the chamber heating system as the heating is profiled to minimise the temperature gradient within the chamber.

3. Control Values Chamber Door HI +4.0 Adjustable +9.0 LO +2.0 Adjustable +6.0 CP (Control Point) -1.5 Adjustable -0.5 0% PULSE -0.5 Fixed N/A 25% PULSE -0.1 Fixed N/A

N.B. Add / Subtract these values from the programmed temperature.

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4. Temperature control operates as follows:

a) When the door is opened the air temperature drops rapidly and the chamber element is allowed to rise to the HI value. It then cycles around this value.

N.B. Control values may have been factory adjusted to suit individual incubators.

b) When CP (Control Point) is reached, the chamber element drops to the LO value. It now cycles around this value.

c) At set point -0.5, heat input is pulsed at 50% until set point -0.1 is reached pulse width is then reduced to 25%.

d) The door operates in a similar way but without pulsing.

5. Normally these control values should not require adjustment, but where the chamber set point is close to ambient they can be decreased, or if the chamber recovery is too slow, they can be increased.

6. The normal running conditions when stability has been achieved for the incubator are as follows:

Chamber Temperature 36.9 37.1 Chamber Element 37.0 38.0 Door Temperature 36.8 37.2 Door Element 34.0 44.0

4.7 Calibration

It is recommended that full temperature and CO2 calibration be carried out annually. The procedure is as follows.

a) Ensure that the customer has left the incubator running at set point overnight, that the humidity tray is positioned correctly with all condensation and spillages wiped dry and that the incubator is left undisturbed.

b) Observe that there is little or no condensation on the inner door seal and none on the inner door or chamber walls. This gives an instant indication that the door temperature is set correctly or otherwise.

c) Place a calibration sensor (or thermometer) in the centre of the top shelf. This point has been found to be a good neutral position, which recovers most quickly after door opening. See sketch on page 12

d) Tape a calibrated sensor to the centre inside of the inner door. Minimise the time that the door is open.

e) Leave the incubator with both doors closed for at least 1 hour to stabilise.

f) Refer to the Calibration Guide 4.1 to adjust the chamber temperature.

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g) Adjust the door temperature to achieve approximately 36.7C at the centre of the inner door. If the door temperature is adjusted significantly, the chamber temperature will require further adjustment.

h) Adjust the element temperatures such that over a period of time:

1. The chamber element varies between about 37C and 38C at its lowest point.

2. The door element cycles between about 34C and 44C.

Four graphs on pages 24 to 28 illustrate how the chamber door and element temperatures vary with time, and temperature recovery after the door has been opened.

4.8 Over-temperature Cut -out and High Temp Trips

1. The over-temperature cut-out relay, mounted on the control PCB is fail-safe and independent of the microprocessor. This will automatically switch all heating off if the chamber temperature rises to greater than 1.0C above set point. It does not require adjustment but it can be overridden by setting the DIP switch on the PCB, as shown on drawing BTC21-811, sheet 1, page 28.

The purpose of the over-temperature cut-out is to stop the chamber overheating in the event of a control PCB failure which leaves either heater switched on permanently.

2. The chamber element high temperature trip switch is behind the rear cover and is manually re-settable. The purpose of this switch is to ensure that no damage occurs in the event of the heating system being left on permanently.

3. The door and fascia element high temperature trip switch can be accessed by removing the display cover on the inside of the outer door, see BTC21-811, sheet 2, page 29.

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5. Calibration Thermometer Placement

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6. CO2 SYSTEM

6.1 CO2 Calibration

a) Programme 0.0% CO2 and take a reading with your analyser. This will give an indication if the CO2 system is properly calibrated.

b) Carry out an Auto Zero as per the User Manual. Note the change in the ZERO REFERENCE FACTOR, a small change indicates that the system was correctly zero referenced.

c) When the CO2 level has recovered, programme 0.0% CO2 and recheck the CO2 level, select CO2 AUTO GAIN and enter the analyser reading. This will automatically adjust the CO2 GAIN FACTOR to give a reading which coincides with the analyser reading.

6.2 Fault Finding

a) CO2 reading stability can be observed by programming 0.0% CO2, and going to the DIAG screen. The CO2 level assuming it is at 5.0%, should not vary by more than 0.05% over a one minute period. If this reading is varying it is probable that the sensor requires replacement.

b) The zero reference factor is allowed to rise to a maximum of 9.900 and in a new incubator the normal setting is between 0.500 1.500. As the sensor ages this number may tend to go up. If it is above 5.000 it is an indication that the sensor may need renewing. If during the auto zero the reference factor falls outside the min/max limits, an alarm signal CO2 Auto / Zero Failure is displayed.

c) If the zero reference factor is unstable with consecutive auto zeros it is an indication that the sensor may be faulty and be replaced as soon as possible.

d) The digital count on the DIAG screen is an indication that the sensor is working correctly, a count of zero or near zero indicates either that the bulb has failed which can be observed or that the CO2 detector itself has failed.

e) Details of the CO2 sensor connections and signals can be found in Chapter 21, see pages 32 & 33.

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7. CO2 Sensor Replacement

1. Programme 0.0% CO2 and degas the chamber thoroughly by leaving the door open for at least one minute.

2. Switch off the power and remove the rear access panel to gain access to the CO2 sensor.

3. Remove the old sensor and replace it with a new one. The sensor PCB is secured by 3-off M3 nuts & washers. Refer to drawing BTC21-815, pages 30 & 31.

4. Replace the rear access panel, switch on and allow the temperature to recover to 37.0C.

5. Carry out an Auto Zero to reference the sensor to atmospheric CO2 and then check the calibration as previously described in Chapter 6.

8. CO2 Sensor Cleaning Procedure:-

The chamber sensors (including O2 & RH sensors if fitted) contain very sensitive electronic components. If liquid of any kind gets into the sensor body, the sensing element will be damaged and any warranty invalidated. The only option we know of for decontamination of the actual sensors is gaseous decontamination. Using the correct equipment and appropriate safety precautions, the incubator can be successfully decontaminated using formaldehyde gas. We have not heard of this affecting the sensors in any way from our customers who have carried out this procedure.

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9. Temperature Sensor Fault Diagnosis

The diagram above shows the procedure to determine if a temperature problem is due to a fault with a sensor or the control PCB itself. If the incubator appears to take a long time to reach 37.0C, it may be possible to speed it up slightly by adding a negative offset to the chamber element sensor. To do this:- Enter the ENGINEERING menu as described in Chapter 3 and by putting a negative offset on the chamber element sensor, you can speed up the heating time. We suggest small adjustments, say 0.5C steps at a time. If too much negative offset is applied, the temperature will overshoot after a door opening.

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10. Chamber Temperature Sensor Replacement

Replacement of the sensor will not affect calibration of the incubator.

1) Disconnect the incubator from the mains supply. 2) Refer to drawing BTC 21-518 on next page for fixing screw locations. With the outer door

open, remove the 2 larger screws and keep in a safe place. 3) Pull the top cover forward, and then lift upwards and clear. The Earth lead should be long

enough so that the top cover can be placed at the side of the incubator. The main control PCB will now be visible. Disconnect the red / white twisted wires from the 1st terminal block (right hand-side of PCB) nearest the front of the incubator.

4) Looking at the rear of the incubator, remove the 17 cross-head screws and washers securing the rear cover .

5) Carefully remove the rear cover. Remove the insulation and cover the heastsink with a paper towel to prevent contact with the sticky, white heatsink compound.

6) The chamber sensor will be visible on the right hand side of the incubator. Remove any adhesive tape securing the sensor wires. With an assistant holding the sensor body from inside the chamber, the retaining nut can be removed.

7) Remove the defective sensor assembly and keep for return to your distributor. 8) From the front of the incubator, refit the new sensor by feeding the wires through the

mounting hole in the chamber until the sensor body is in the correct position. With an assistant holding the sensor body, tighten the retaining nut. Do not over-tighten as the sensor body is plastic and easily be damaged. Tape the ends of the wires from the new sensor to a steel rule or similar object, and carefully feed it along the channel under the equipment tray until it is visible in the rectangular cut-out. Remove the tape, and route the wires to the control PCB. Cut to length, bare the ends and reconnect to the PCB. The sensor is not polarised and the red / white wires are interchangeable. Remember to replace any adhesive tape which holds the sensor wires in position.

9) Check everything for obvious faults, and re-assemble the incubator in the reverse order to above.

10) Return the defective sensor to your distributor for investigation.

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11. Top Cover Securing Screw Location

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12. EPROM Replacement Flow Chart

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13. EPROM Replacement Procedure

Materials & tools required:-

IC Extractor tool (or small screwdriver). Large Flat-bladed screwdriver. ESD wrist strap (preferably complete ESD workstation with conductive mats & earth bonding straps)

To replace the EPROM:-

1) Disconnect the incubator from the mains supply.

2) Remove the top cover as detailed in Chapter 9, page 16.

3) Ensure the ESD wrist strap is correctly and safely connected to a suitable Earth point, and that you are wearing it in accordance with the manufacturers instructions.

4) Locate the EPROM. The EPROM is the IC centre-left on the control PCB. It will have a white label with GALAXY R printed on it.

5) Carefully remove the IC using an IC extractor or small screwdriver as a lever. Try not to damage the device.

6) Install the new EPROM with the notched cut-out facing towards you (front of the incubator). Ensure that each pin of the IC is in the socket fully and correctly.

Re-connect the power to the incubator, and switch on. The incubator will prompt you to enter a serial number. Use the arrow keys to enter the serial number (to check the original serial number look at the front fascia of the incubator. The serial number will be visible on the blue warning label). This serial number is used to ensure the correct CO2 curve and bulb- flashing rate are applied to the CO2 sensor. Incubators after serial No. 2557 (inclusive) are fitted with a new type of CO2 detector having a sapphire window. This has slightly different characteristics which affect calibration. Entering the serial number allows the software to select the correct CO2 curve and bulb-flashing rate for either new or old sensors. If a serial number prior to 2557 is entered the incubator will ask if a new CO2 sensor is also being fitted. For a complete explanation refer to Chapter 3, section 8.

7) When you are sure the incubator is working correctly, replace the top cover and replace the fixing screws.

8) Return the old EPROM to your distributor in the same packaging the new EPROM arrived in.

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14. Membrane Keypad / Display Replacement

Materials & tools required:-

Replacement keypad or display Sharp blade (for keypad replacement only). Soapy water / sponge / lint free cloth 5mm A/F miniature nut runner (some early models may require 5.5mm). PVC insulating tape, black (for keypad replacement only). ESD wrist strap (preferably complete ESD workstation with conductive mats & earth bonding straps - for display replacement only)

To remove the old keypad (display removal steps 1 to 5 only apply)

1) Disconnect the incubator from the mains supply.

2) Ensure the ESD wrist strap is correctly and safely connected to a suitable Earth point, and that you are wearing it in accordance with the manufacturers instructions.

3) With the outer door open, there will be an access panel visible in the upper centre area of the door held in place by 4 screws. Support the access panel, and remove the screws, remove access panel and keep in a safe place.

4) With the access panel removed, the door insulation will be visible. The insulation has a removable section to allow access to the display compartment. Carefully remove the insulation and place to one side.

5) On the left hand side of the display are an 8-way, and a 10-way connector. Carefully unplug them (grasp the connector bodies, not the wires). All the connectors are polarised so it is not possible to connect them wrongly. Above the display should be visible a 6-way connector joining the keypad to the door cable harness, remove it taking care not to lose the pin header which joins the keypad to the wiring harness. Above the display is a small PCB which has a connector at each end of it. Carefully disconnect the larger black connector from the PCB (grasp the connector body, not the wires).

6) With the display disconnected, the retaining nuts & washers can be removed and placed in a safe place. Under the display and fitted to each screw will be a number of spacer washers make a note of how many washers are under each screw before removal. Carefully remove the display and place in a safe area where it will not be scratched or be exposed to dirty / dusty / humid conditions. The display should also ideally be stored in a ESD safe area (conductive area to prevent electrostatic discharge from damaging the display).

7) Remove and discard the black PVC insulating tape from around the display aperture. Remove and tape from the display support bar (flat rectangular metal plate) and keep in a safe place.

8) Close the outer door again and using the old keypad as a guide, carefully score the paint round the edge of the damaged keypad with a sharp blade to prevent the painted surface of the door peeling off when the keypad is removed. To remove the keypad itself, start at one of the corners along the bottom edge of the keypad and peel slowly upwards.

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To fit new keypad (for display refitting steps 12 to 15 only apply)

8) If there are any traces of old adhesive left behind, gently remove using a sharp blade to shave the surface flat. Gently sponge around the area under the keypad and the inside of the display aperture with soapy water to remove any surface contaminants. Dry thoroughly with the lint free cloth.

9) Feed the keypad connection tail through the aperture. Remove the backing paper (including the small piece behind the flexible connection tail), and carefully press the keypad into position. The keypad must be positioned accurately as it cannot be repositioned once stuck in place. Smooth over the joint to ensure there are no air bubbles trapped under the adhesive. Handle carefully as the display window is relatively easily scratched.

10) Replace the display support bar so that it fills the gap to the left of the flexible connection tail.

11) Working from the inside of the door, place overlapping strips of black PVC insulating tape around the inside edges of the keypad and display aperture to make a frame. The idea being to mask off all of the internal keypad area up to the actual display window. This forms a blackout and prevents any light from the backlight from showing through the keypad area. Ensure that the tape is not visible from the outside of the display window and also that the tape is pressed well into the corners of the aperture.

12) Re-fit the display and associated nuts and washers do not fully tighten yet. Ensure the display area is spotless and clean, as any debris will be very obvious when the incubator is operating.

13) Replace all connectors (the only connector which may cause some confusion is the actual keypad connector ensure the pink / black wire is on the left hand side).

14) Switch on the incubator and check the display is centered and free from debris. When the display is in the correct position, the fixing screws can be tightened fully. If the display appears blank, very feint or all white, slowly adjust VR1 on the Control PCB to adjust the contrast of the LCD.

15) Replace any insulation and the access panel.

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15. Membrane Keypad Testing

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17. Temperature Recovery Graphs

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19. Incubator Wiring Schematic

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19. Incubator Schematic Display Wiring

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20. Cross-section through CO2 Sensor

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21. CO2 Detector Assembly

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22. Galaxy R CO2 Sensor Connections

Pin-out of the Galaxy R CO2 connector.

PIN WIRE COLOUR FUNCTION DESCRIPTION 1 YELLOW CO2 SIGNAL Signal from sensor 2 RED 2x VREF 5.0v reference for CO2 sensor 3 BLACK 0VA 0v for sensor 4 GREEN BULB (-) 0v for bulb 5 ORANGE BULB (+) Bulb drive supply

The sensor signal is measured between pin 1 and pin 3:

SCALE: 200mV per vertical division 200ms per horizontal division

The signal measured in ambient air is approximately a sine wave with a peak of 750mV and a trough of 400mV. An amplitude of 350mV on a DC offset of 590mv. As CO2 is introduced into the sensor chamber, the amplitude decreases such that the greater the CO2 level, the smaller the amplitude. The brass sensor chamber has a stainless steel insert in the light path between sensor and bulb to resist tarnish and effective loss of light intensity.

The 5.0v reference for the CO2 sensor is measured between pin 2 and pin 3. This is a DC voltage which is locked to a precision voltage reference to minimise temperature and ageing drift. This should measure 5v 50mV (1%)

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The bulb waveform as measured between pin 5 and pin 4:

SCALE: 1V per vertical division 200ms per horizontal division

The bulb drive waveform is a square wave with a peak of 3v and a trough of 1v, locked to the same precision voltage reference as pin 2. The waveform oscillates at 0.357Hz with a 50% duty cycle locked to a quartz crystal. The bulb minimum voltage of 1v is to maximise bulb life by avoiding cold starts since the filament is always at least red hot. The bulb is rated at 5v but runs at a maximum of 3v for the same reason.

The reason for two 0v rails being present on the sensor PCB is to avoid voltage drop on the bulb 0v from being seen as part of the CO2 signal. The two 0v rails are kept separate from the sensor PCB right up to a star 0v ground at the power supply on the main PCB to eliminate this error voltage source.

The bulb can be checked by disconnecting the CO2 connector from the Galaxy R main PCB and measuring the resistance of the bulb between pins 4 and 5 (Green and Orange). The resistance should measure approx 4.5

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23. CO2 Flow Path Schematic

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24. Control PCB Fault Diagnosis

Hints and tips to help diagnose PCB faults in the field.

Display Faults:- If the display is blank or displays garbage, it is possible to tell whether the control PCB is still working by pressing any button on the keypad to trigger a beep. If the beep is heard the fault is very likely with the display, display cable or associated circuitry on the control PCB. If no beep is heard, the fault is likely to be a control PCB failure or the control PCB has hung up for some reason, eg. - a poorly soldered joint suddenly going open circuit.

This test is best done when the fault is apparent since switching the incubator ON and OFF will often cure the fault, particularly if it is an intermittent fault.

Choose a neutral key which does not normally do anything in itself - eg the key. This is to avoid accidentally making any changes, as it may not be possible to tell what menu you are currently in.

If the display appears blank, very feint or all white, slowly adjust VR1 on the control PCB to adjust the contrast of the LCD.

General PCB Faults:- A misaligned IC pin during fitting can result in the pin being bent. This can lead to a fault occurring either immediately (pin not in contact), or later due to temperature effects (physical movement) or oxide formation between the poor contact surfaces.

PCB & EPROM numbering explained:- Note about EPROM firmware revisions The firmware revision number (begins with BA) eg BA2703001204 is unique every time the EPROM software is updated. It is composed of 5 pairs of digits:

BA2703001204 ^^ Firmware revision number ^^ Date ^^ Month ^^ Last 2 digits of the year ^^ Hour ^^ Minute

This date and time system is guaranteed to be unique for 100 years and denotes the time when the firmware changes were actually made to the source code.

The control PCB revision number is constructed in a similar way:

HAD0908001909 ^^ PCB revision number ^ Capability Level. If a new feature is added this letter increments ^^ Date ^^ Month ^^ Last 2 digits of the year ^^ Hour ^^ Minute This date and time denotes a point in time when the board changes were actually made to the PCB layout.

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Control PCB fault diagnosis if the incubator does not function correctly:-

On a 'dead' board, check to see if the watchdog LED is flashing (only LED on 'Board One')

The independent watchdog processor serves two purposes:

Over-temperature Cut-out:- If the temperature of the chamber is greater than 1.0C above setpoint, power to the heaters and 24v supplies to the valve(s) is removed until the temperature falls below setpoint +1.0C

Intelligence Test:- The watchdog communicates constantly with the main processor and regularly performs an 'intelligence' test lasting around 82 seconds. If the main processor fails this test, the watchdog will restart the main processor in an attempt to regain normal control. After 10 attempts, the watchdog will remove mains power to the heaters and 24v supplies to the valve(s) since the main processor cannot reliably control them. Restarts will continue until the main processor passes the 'intelligence' test and a temperature measurement below setpoint +1.0C is reported (if a fault is present, this will not happen without the fault being repaired).

This should restore normal operation if failure was due to an intermittent fault that has subsequently cleared itself. eg nearby lightning strike or intermittent hardware fault.

LED Flashes:- 0 Watchdog has failed or board psu fault 1 Watchdog has failed or board psu fault 2 Normal operation 3 Watchdog has issued a reset instruction (watchdog detected an error during

'intelligence' test) 4 Watchdog has opened the mains relay (Over-temperature cut-out) 5 Both 3 & 4 occurred

Note 1: If disabled, only 2 & 3 occur. Cycling the power ON / OFF resets the status of watchdog LED.

Note 2: On boards prior to HAD0908001909 (HAA, HAB or HAC 'Board One') removal of the 24v supplies to the valve(s) also results in the LCD display backlight going out.

If the control PCB appears to be working normally (but not heating up or switching on valve(s) and the LED is not flashing / constantly on / or other unusual behavior), the fault lies with the watchdog or its support circuitry. Try fitting a new watchdog IC (U18) to see if this cures the fault.

Reset to Defaults:- This should only ever be done in the field if fitting a new U1 IC (which will contain random data) to quickly load all programmable settings to defaults rather than going through them one at a time. It performs no other useful function. If done in the field, the parameters for that incubator should be recorded and re-entered after the reset has been carried out (eg temperature offsets and CO2 factors etc).

Note:- Reset to defaults has no effect on the A/D calibration parameters which are different for each IC. Time and date settings are also unaffected by a reset.

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Function of U1:- Stores the following parameters in battery-backed memory: Setpoints Control points Factors Incubator type Alarm events log and graphs (not O2 or Rh graphs) Maintains date & time

If any problems in these areas are observed, a problem in communication with this IC would show up on the top screen where the clock is displayed as the IC is queried for time data constantly. The time and date may flicker with random data or may not update at all.

Function of U2 (EPROM):- Stores the software program that operates the incubator. Any faults in communicating with this IC can produce any number of strange malfunctions, to not starting at all.

From version BA2703001204 onwards, a 'ROM Checksum' menu helps diagnose this type of fault. The board constantly adds all the bytes in the EPROM together and displays the sum as a hexadecimal number on the display. Once a checksum is determined, the process repeats to generate a new checksum. This new checksum should match the previous one, if it does not (eg - due to an intermittent fault), the 'ROM CHECKSUM CHANGED' counter is incremented and displayed. A value other than zero is very suspicious. NB:- The counter is reset to zero at power on, check it before switching off! If the board has a permanent fault, the checksum could be incorrect, but never change, so the displayed checksum should be checked against the known good checksum for that EPROM version (which changes with each version and can be supplied on request). The entire EPROM is checked and the display updated every 12 seconds.

Display Faults:- Every second the control PCB tests the display, the connection to the control PCB and the display driver circuitry, by writing an eight-bit pattern to display memory in an area not visible to the user. The pattern is then read back, and the result should be identical. If it is not identical, the LCD failure sound is heard. This cycle will repeat indefinitely.

This integral check can be useful to help identify which component is at fault: - the control PCB, the display itself, or the connecting cable. If a spare display and cable assembly are available, this can be substituted for the internal display to help determine where the fault is.

One or more white lines:- If any white lines are visible on the screen that persist despite changing from one menu to another, the display itself is most likely to be faulty. Moving from one menu to another clears the entire screen before the new menu is redrawn.

Random white dots:- Check inverter connections at the display on the wires from the fluorescent tube to inverter and soldered pins on the inverter socket these wires plug into. Due to the high voltage on these lines, a bad connection can cause arcing, generating a large amount of RF interference. The display can pick up the interference and displays the noise as white dots or lines.

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25. Molex IDC Connector Assembly

Insulation Displacement Connectors (IDC) are used in the Galaxy series of incubators because they are quick, easy and reduce costs by eliminating wire stripping and crimping or soldering. The actual joint is made by forcing the wire into a slot in the connector terminal. The slot has blades which pierce the insulation and make contact with the bare wire. This is shown in the diagram below:-

When done with the correct tool, it produces a gas tight, high pressure joint between wire and terminal. In IDC terminations insertion depth is important. Using the correct tool ensures that the wires are pressed into the blades to the correct depth (contact your distributor for tool ordering details).

Molex IDC Connector Hand Tool (RS Biotech Part No: 170-754):-

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26. Lost User Access Code Recovery

If the user has forgotten or lost a previously entered Access Code, it can be changed or retrieved by:-

1) Press DIAG 2) Select ENG 3) Using the left / right arrow keys, enter the ENGINEERING ACCESS CODE of '1973' (factory set - cannot be changed) 4) Press ENTER 5) Select USER ACCESS CODE 6) Press ENTER The existing User Access Code will be displayed. If you wish to change the Access Code, enter a new code. If you wish to remove the Access Code, program a code of '0000' by pressing the RESET key. 7) Press EXIT 3 times to return to the main screen.

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27. Gas & Gas Regulator Specifications

A large size cylinder of " CO2 - Vapour Withdrawl" is required to supply the incubator with CO2. Your gas supplier will have a standard size of about 18,000 litres, normal commercial grade CO2. You will also require a suitable CO2 regulator with cylinder and supply pressure gauges which can be supplied by your gas supplier. It should be suitable to regulate the pressure to 0.35 Bar (5lbf / in2). Suggested range 0 - 2.0 Bar (30lbf / in2).

The CO2 cylinder contains liquid CO2 at a vapour pressure of 50 Bar. The gas vapourises from liquid, therefore the cylinder pressure is always 50 Bar. When the gas pressure starts to drop, the liquid is completely vapourised and the cylinder is almost empty.

Average CO2 consumption is about 10ltrs per 24hrs, with a further 10 ltrs used each time the door is opened. Under typical usage conditions a cylinder should last for several months.

If the incubator is a 0.1 19% O2 control model working below ambient O2 levels, Nitrogen will also be required. The Nitrogen cylinder is also a standard large size cylinder containing about 8,000ltrs of normal commercial grade gas at around 230 Bar pressure. You will require a suitable N2 regulator with cylinder and supply pressure gauges which can be supplied by your gas supplier. It should be suitable to regulate the pressure to 1Bar (15lbf / in2). Suggested range 0 - 2.0 Bar (30lbf / in2). In this case the cylinder contains pressurised gas, so as the N2 is used the pressure goes down. Nitrogen consumption is higher than CO2 and dependent on the programmed level. For example to achieve 10% O2, Nitrogen consumption would be about 50ltrs each time the door is opened and about 20ltrs per 24hrs.

The N2 & CO2 regulators require a 6mm diameter male hose tail for connection to the 6mm bore tubing supplied with the incubator. If the gas cylinders are more than 3 metres away from the incubator you will require more 6mm bore, 9mm outside diameter PVC tube. To connect the CO2, Oxygen & Nitrogen supplies to the incubator use the 6mm plastic tubing to connect the gas supplies via the HEPA filters at the rear of the incubator. Use the tubing clips provided to eliminate gas leaks.

Set the N2 and CO2 pressures according to the chart below, dependant on the programmed level of O2 required.

O2 Prog. Level: N2 Pressure: CO2 Pressure:

BAR psi BAR psi

10% or greater

0.35 5 0.35 5

5% or greater

0.70 10 0.70 10

1% or greater

1.00 15 1.00 15

These values are guidelines only, they can be modified to speed up or slow down recovery. The programmed O2 and CO2 level should be achieved within 2 to 3 minutes of one another, otherwise the O2 level may go too low because CO2 is continuing to be added after the O2 level has achieved the programmed value. (the addition of CO2 also depletes the O2 level)

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NB - Ensure the correct gas is connected to the correct inlet!

Turn on the gas supplies when the incubator has reached the programmed temperature.

NB: Dependant on the programmed gas level, it may be advisable to install an automatic cylinder changeover unit to eliminate the risk of Nitrogen or Oxygen supply failure. A typical changeover unit installation is shown diagrammatically on the next page.

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28. Typical Automatic Gas Changeover Unit Installation

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29. Chamber Seal Replacement

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30. 3 or 6 Door Frame Replacement

This instruction covers complete replacement of a 3 or 6 door frame. Due to the evolution of the design, there a have been a number of different door closure mechanisms used. The initial door was held closed by a screw closure and a threaded insert in place of the usual magnetic catch. This system proved tricky to fit and even more difficult to retro-fit. In late 2001 a more user friendly design was introduced which made use of the standard magnetic catch and a magnet plate / knurled knob component (illustrated on page 46). This design was more easily factory or retro-fitted. In early 2002 this trend was continued with a new design incorporating holes in the frame to attach a standard magnet plate directly to the 3 or 6 door frame itself. The instructions which follow are equally applicable to any version of the 3 or 6 door frame, the only slight differences may be in the door closure mechanism.

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46

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31. Cooled Galaxy R

Refer to drawing BTC 21 - 566, 2 sheets, pages 50 & 51.

This incubator uses a pair of Thermo Electric Coolers (TECs or Peltier devices) to electrically pump heat from the chamber interior to the outside. To maintain an even temperature in the chamber, air is circulated across the cooled (interior) heatsinks by a fan. The chamber circulation fan draws air from the chamber and directs it through an L shaped internal baffle and across the cooled heatsinks and exits from a series of slots and back round the chamber. The heat removed by the cooled heatsinks (interior) is transferred to the ouside by a pair of TECs sandwiched between the cooled (interior) heatsinks and the warm (exterior) heatsinks. Heat from the warm (exterior) side is then exhausted to atmosphere by forced fan cooling of the warm (exterior) heatsinks. Air is drawn in and directed over the heatsinks, being exhausted at the top and bottom of the rear fan mounting plate. The incubator requires a 50mm air gap at the rear to allow the fans to operate efficiently.

Cooling Operation

Refer to the circuit drawing BTC 21 - 568, sheet 2, page 52

There are 3 operating modes accessible via the keypad.

Normal Mode

In this mode the cooling system is off. The external fans and TECs are off, but the chamber circulation fan still operates. This mode should be used for working at 37C in ambient temperatures up to a maximum of 32C.

Ambient Mode

This mode should be used where the ambient temperature is likely to vary above and below the programmed temperature.

The heating and cooling systems are on. The cooling fans run continuously and the TECs are switched on and off by the control PCB. The bridge rectifier supplies rectified AC which is then roughly smoothed by the capacitor to approximately 10VDC. The capacitor is mounted next to the chamber fan motor cooling fan to aid cooling.

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Cooled Mode

This mode should be used where the ambient temperature is above the programmed temperature.

The lowest temperature that can be achieved is 7 to 8C below the warmest room temperature. The customer therefore would normally be expected to work at up to 5C below the warmest ambient temperature.

Testing the Heat Exchangers

The voltage across the TECs (measured at the capacitor), should be around 10VDC when the TEC is on. To determine if each TEC is working it is necessary to measure the current flow through the device. If the rear CO2 access cover is removed, access can be gained to the bullet connectors joining the TECs. These bullet connectors are a convenient way of breaking the circuit to insert an ammeter to check current. Current drawn by a working device should be between 4 - 5 Amps. In early versions (pre 2002) of this incubator, all wiring was made using blue & brown mains cable. This led to confusion during manufacture and servicing of the unit, and in 2002 the wiring was changed so that supply and return wires for each TEC were made a different colour to aid identification. In mid 2002 a potential problem was highlighted regarding protection of the toroidal transformer. An additional fuse has been added in series with the transformer primary to protect the transformer and wiring. The fuse must be a Littlefuse 213 series, 1A, type T. If the additional fuse was retro-fitted, it will be an in-line type fuseholder. If the fuseholder was factory fitted, it will be of the chassis mounting type with a clear plastic cover.

Adjustment of the Chamber Fan V Ring Seal

The chamber is sealed by a V ring seal mounted on an adaptor fitted to the fan motor shaft, see drawing BTC 21 - 566, sheet 2, page 51. The V ring needs to be adjusted carefully to ensure that it is sealing the chamber, but not tightened so much that it creates resistance and the fan cannot not turn freely. Push the seal up carefully with the fan until the lip of the seal is just compressed. To check the position, switch on the incubator and allow the fan time to run up to speed. Switch off again. When correctly adjusted, the fan should take between 5 7 seconds to come to rest. Once the seal is in the correct position it can be clamped in position by the fan.

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Replacement of a Thermoelectric Module

1) Remove the rear CO2 access plate and disconnect the bullet connectors. NB if there is any doubt or possibility of confusion in wire identification, label both sides of each joint before disconnection!

2) Remove the rear fan plate. The toroidal transformer, bridge rectifier and cooling fans will remain attached to the fan plate.

3) The warm heatsinks (exterior) can be removed by unscrewing the 8-off retaining screws. Unscrew in a cross-pattern to minimize distortion.

4) The TEC will now be exposed and can be removed by gently pulling it towards you. Ensure the aluminium spacer block is not lost. All joints between TECs and heatsinks / spacer blocks must have a generous coating of heatsink compound to improve thermal conductivity. Any heatsink compound used must have a high thermal conductance capacity, eg RS part No. 217 3835.

5) If the aluminium spacer block is removed, recoat with heatsink compound and replace in position against the cool (interior) heatsinks.

6) Coat both sides of the replacement TEC with an even layer of heatsink compound. Place in position and replace the warm heatsinks. Ensure both sides of the TEC are in complete contact with the spacer block and the warm heatsinks. If there are any gaps or irregularities between the thermal surfaces, efficiency of the system will be drastically reduced. It is recommended that a trial run be carried out before final tightening of the warm heatsinks Press the warm heatsink into position, then remove it again. When removed, there should be a complete square witness mark of heatsink compound.

7) When the position has been checked, and is correct, carefully tighten the warm heatsink securing screws in a cross pattern to reduce the possibility of distortion occurring.

8) Replace the rear fan plate. 9) Reconnect all bullet connector joints. 10) Replace rear CO2 access plate. 11) Switch on and check operation.

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32. Cross-section through Cooled Galaxy R

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33. V Ring Seal Adjustment on Cooled Galaxy R

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34. Cooled Galaxy R Wiring Schematic

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35. 110V High Temperature Galaxy R Description

Refer to the schematic on page 54. The 110V high temperature variant has the same basic construction as the 230V high temperature model, but with modified element wiring to accommodate the lower mains voltage. The main control PCB also requires some modifications to cope with the additional current demands created by the high temp cycle. Mains power comes in via a 10A unfiltered switched inlet and an 8A fuse, before passing through a 10A RFI filter. All mains wiring must be 18AWG. The fascia and door elements are wired in parallel, giving an in-circuit resistance of around 21.5. The chamber element consists of 2 elements wired in parallel giving an in circuit resistance of around 129. Each element has an over-temperature cut-out switch in series with each element half. The heavy current means that the element switching Triac (Q1) on the control PCB must be mounted on a separate heatsink, and the PCB tracks connected to Q1 must be thickened with solder and insulated with hot melt glue.

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36. 110V High Temperature Galaxy R Schematic

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37. Oxygen Control General Description

Refer to the wiring schematic on page 57, showing the additional components required for oxygen control. The sensor should regularly be referenced to atmospheric oxygen levels as detailed in the User Manual.

Safety at high Oxygen Levels.

The solenoid valve controlling the gas supply is degreased and regulators / gauges etc. must be grease-free for use with oxygen. The user should follow normal precautions in the immediate vicinity of the incubator during door openings ie avoid naked flames which might flare up and avoid the presence of other combustible gases such as hydrogen or methane etc.

Condensation problems.

If the oxygen sensor fails suddenly (within a period of a few hours), it is very likely that the sensor inlet membrane has become blocked by condensation. Condensation build-up on the membrane can occur for a variety of reasons:-

The incubator has been switched off whilst humidified. The rear access cover has not been re-fitted by mistake. The bottom of the chamber has been flooded.

This type of sensor failure can be seen on the datalogger screen as a sudden drop from the programmed value to around zero.

The sensor membrane is hydrophobic and therefore it is not possible for condensation to build up within the sensor itself. Even if this did occur, it would dilute the electrolyte reducing the signal, but would not cause a failure.

To dry the sensor membrane:-

Program the incubator for a temperature of at least 37C (or higher if being used at a higher temperature). Program 0.0% CO2 and disable the oxygen control in the USER menu. Remove the humidity tray and dry all traces of condensation in the chamber. Wipe the white sensor membrane area of the oxygen sensor with absorbent paper to dry off excess condensation. Close the door and allow the temperature to recover. Re-open the door for 15 seconds to release any build up of humidity. Repeat approx every 30 minutes. Observe on the datalogger O2 graph that the oxygen level should suddenly recover after a few hours. Leave the incubator for a further few hours to ensure that the membrane has thoroughly dried out. Re-humidify the incubator and leave it for 2 or 3 hours, then carry out an OXYGEN SENSOR REF TO ATMOSPHERE in the USER Screen. When the referencing has been completed the incubator is ready to use.

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Sensor Life Span.

The oxygen sensor is a self-powered, electrochemical cell having a finite life dependent on ambient oxygen levels, typically 1-2 years at atmospheric levels. Reduced oxygen levels will increase sensor life - increased oxygen levels will reduce sensor life. During the sensors life the signal will gradually degrade until it is un-useable. The output from the sensor can be measured from the connecting lead of the sensor, directly across the sensor, or across J9 on the control PCB. Output from a new sensor should be between 9 14mV and should be checked whilst the sensor is in situ. If the output falls below 3mV the sensor will not auto reference and a warning message will appear on the screen. The incubator will continue to function normally, but oxygen control will be disabled until a new sensor is fitted and correctly referenced to atmosphere. Sensor output is related to the auto reference factor as follows:-

Auto Reference Factor 0 0.5 1 2 4

UNUSABLE OK OK POOR but USABLE

0 25 12.5 6.25 1.5

Sensor O/P (mV)

MOX-1 Sensor Dimensions and Connector Pinout:

Technical Specification:

Sensor Type: Self-powered, diffusion-limited, electrochemical cell with temperature compensation.

Zero Signal in Nitrogen:

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38. Oxygen Control Schematic All Variants