Alarm error skin sensor 1

Warmer Technical Manual

Please Read

All maintenance should be undertaken by qualified service personnel.

Fisher & Paykel Healthcare has a policy of continued product improvement and reserves the right to alter specifications without notice. This manual covers IW900 Series Infant Warmers and accessories with controller software version up to and including 3.00 and controller printed circuit board revisions up to and including Rev A.

Warranty

Subject to any agreement to the contrary, the product described in this manual is warranted against defects in materials and workmanship for one year from the date of shipment. However, the warranty is void if the product is damaged as a result of mishandling, accident or misuse. In no event shall the manufacturer be liable for incidental or consequential damages (eg. loss of use) resulting from breach of warranty. All other expressed and implied warranties under law is excluded to the extent that it can be lawfully excluded.

Warmer Technical Manual

Warmer Technical Manual

Warmer Technical Manual

Warmer Technical Manual

PART 2: Operation and General Information

2.1Product Overview

Warmer Technical Manual

2.2Heater Power Control

2.2.1Modes of Power Control

MANUAL MODE BABY/SERVO MODE

POWER COMPENSATION

= PCeiling V−2

PDelivered PDisplayed 7.5%

100 V 2

Where:

PDisplayed is the displayed power level (Power Display).

When in Baby Mode, the power is controlled to a resolution of 1%. Power is delivered in an optimally smooth pattern of mains pulses which repeats every 2 seconds at 50 Hz (1.7 seconds at 60 Hz). This even power control helps to reduce ripple in the baby or patients skin temperature. The power level is automatically adjusted ten times every second.

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LIGHT INDICATOR AND BUTTON

The Light Button toggles the examination light off and on. The Light Indicator is lit when the light is on and extinguished when the light is off. If the light fails during use a short tone will sound and the light indicator will extinguish. If the light is turned on with a faulty bulb, the indicator will turn on, there will be a short tone and the indicator will extinguish.

MANUAL INDICATOR AND BUTTON

The Manual Button begins Manual Mode. The Manual Indicator will be lit if the button is pushed.

CONTROL KNOB

Adjusts set temperature in Baby Mode and set power level in Manual Mode. Adjusts preset start times when either the Timer 1 Button or the Timer 2 Button is held down (IW910, IW93x, IW960 & IW980 only). Also used in Information Mode (see Section 2.5).

BABY INDICATOR AND BUTTON

The Baby Button begins Baby Mode. The Baby Indicator will be lit if the button is pushed.

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CHECK BABY ALARM

In Baby Mode this alarm means the output power has been at 100% for at least 15 minutes indicating that the baby is slow rising to the set temperature and should be checked. In Manual Mode this alarm means the output power has been above 25% for at least 15 minutes indicating that the baby should be checked.

HIGH SKIN TEMP. ALARM

In Baby Mode this alarm means the baby skin temperature exceeds the set temperature by at least 1.0°C. In Prewarm Mode or Manual Mode this alarm means the baby skin temperature exceeds 39°C.

CHECK BABY ALARM

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2.5Information Mode

Information Mode allows additional information about the warmer to be obtained by the front panel controls and displays. Information mode is intended for use by technical personnel only and should not be used while the warmer is in use. Information mode is used for calibration and diagnostics.

Warmer Technical Manual

2.6Error Codes

EIN #7 shows the error code corresponding to the last See Manual alarm. This value is kept in nonvolatile memory and is updated every time a new error code occurs.

NOTE: Error codes are retained indefinitely and may only change when a new error occurs.

See section 2.5 for access to Information Mode.

The possible error codes are:

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TEMPERATURE SENSOR

Twin YSI 400 compatible thermistors with 100 MΩ insulation at 500V between all electrical contacts and the skin surface

Warmer Technical Manual

Warmer Technical Manual

SUPPLY VOLTAGE AND CURRENT

Mattress irradiance is 32 mW/cm² at 100% heater power and 68 cm (26.8”) heater grill to mattress distance

TEMPERATURE RANGE TEMPERATURE MEASUREMENT

TEMPERATURE SENSOR

Twin YSI 400 compatible thermistors with 100 MΩ insulation at 500V between all electrical contacts and the skin surface

Warmer Technical Manual

SUPPLY VOLTAGE AND CURRENT

Mattress irradiance is 32 mW/cm² at 100% heater power and 68 cm (26.8”) heater grill to mattress distance

TEMPERATURE SENSOR

Twin YSI 400 compatible thermistors with 100 MΩ insulation at 500V between all electrical contacts and the skin surface

MATTRESS HEIGHT BASSINET SIZE (STANDARD)

Dependent on installation. 65 cm x 65 cm (25.5” x 25.5’)

Warmer Technical Manual

TEMPERATURE SENSOR

Twin YSI 400 compatible thermistors with 100 MΩ insulation at 500V between all electrical contacts and the skin surface

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2.10Environmental Specifications

2.11Equipment Classifications

Class I, Type B

with Class II, Type BF applied part Continuous operation

Not classified against ingress of liquids

Not suitable for use in the presence of flammable anaesthetics

2.12Standards and Approvals

Designed to conform to the requirements of:

IEC 60601-2-21 IEC 60601-1 IEC 60601-1-2 UL 2601-1

AS 3200.1.0

CAN/CSA C22.2 No. 601.1 EN 60601-1

ISO 8382 *

*Neopuff™ Infant Resuscitators only

2.14Electromagnetic environment

2.15Material statements

The IW900 series warmer and accessories do not contain patient contacting PVC devices plasticized with DEHP.

Warmer Technical Manual

Warmer Technical Manual

PART 3: Maintenance and Servicing

WARNING

All maintenance should be undertaken by qualified service personnel.

3.1Maintenance Schedule

Fisher and Paykel Healthcare recommend that the following Safety, Performance and Functional checks be performed at least annually for all models covered by this manual. It is important to follow hospital and local regulations if more frequent checks are stipulated.

NOTE: A maintenance check sheet is provided in 3.7.

Equipment

Depending on the extent of the service check and the accessories included on your warmer the following equipment may be required.

All electronics are calibrated during manufacture. Regular calibration is not necessary. A check of calibration is included in the Performance Check.

3.2Safety Check

WARNING Connect the power cord only to a properly grounded wall receptacle that is approved for hospital use and of the correct voltage. DO NOT use extension cords or an AC receptacle box for this device.

The unit should be tested to the current medical electrical standards for in-house testing for each specific country (example, refer to UL2601-1 for USA, EN60601-1 for Europe, AS/NZS 3551 for Australia and New Zealand). This should be done prior to initial use and at least annually thereafter.

NOTE: To conduct an earth test, the test lead should be attached to a bolt located under a plastic cap at the top of the column – refer diagram 6.2.2 part 5.

NOTE: The Transport Handle is not earthed but is protected in accordance with clause 17a)3) of IEC60601-1. To verify safety conduct a Patient Leakage Current Test under normal operating conditions. The pass criterion is less than 0.01 mA DC or 0.1 mA AC.

NOTE: The Medela Phototherapy Unit is double insulated. To verify safety conduct a Patient Leakage Current Test on the metal arm under normal operating conditions. The pass criterion is less than 0.01 mA DC or 0.1 mA AC.

NOTE: For neoBLUE-mini phototherapy refer to 185043921 service manual

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3.3System Check

This procedure is the recommended performance check for Fisher & Paykel Radiant Warmers. A check of calibration is included.

Warmer Technical Manual

Warmer Technical Manual

Warmer Technical Manual

3.5Service ProceduresReplacement

Anti-Static procedures must be observed when handling printed circuit boards (PCB’s). Qualified service technicians should carry out all servicing.

3.5.1Replacement of Halogen Lamp.

a.If the warmer has been running then allow one hour for the heater and lamp to cool.

b.Unplug the mains cable which supplies power to the unit. Turn off the UPS if installed

c.Unlatch the wire clips from the front of the head and remove the screw underneath the front of the head which secures the lower case to the upper case. The rear screw will also need to be removed on heads manufactured after August 2002.

d.Support the front of the head and pull both sides of the lower case down to open.

e.Pull the halogen lamp out. Using gloves to protect the new lamp, install by pushing into receptacle. Use only 12V 20W 50 mm halogen lamps (Fisher and Paykel part # 424040069).

f.Close the lower casing of the head and replace the securing screws and wire clips.

g.Press the lower case along both sides to ensure it is clipped firmly into place.

3.5.2Replacement of Controller Fuses.

a.Unplug the power cable from the wall supply outlet. Turn off the UPS if installed.

b.Remove the four screws that secure the front control panel to the column (located behind the column).

c.Pull the front panel away from the column until the printed circuit boards are revealed.

d.Disconnect J12 (ribbon cable) from the control PCB. Disconnect J3 (ribbon cable) from the power PCB. Disconnect J6 and J13 (power switch) from the power PCB. Remove the front panel.

e.Controller fuses F1, F2, F3, F4 and F5 are located on the power PCB. Replace as necessary.

f.Hold the control panel beside the column and reconnect connectors J12, J3, J6 and J13. .

g.Replace the front panel checking that it does not interfere with any wiring harnesses, in particular ribbon cable (7) on controller assembly diagram 6.2.2

h.Replace the four screws.

3.5.3Replacement of Supply PCB Fuses (IW93x, IW95x, IW960 and IW970 models only)

These include fuses for the Electric Elevator Module (if fitted), the Power Outlet (if fitted) and any accessories that may be fitted. Refer to the photo in section 5.4.3 for fuse positions.

a.Unplug the power cable from the wall supply outlet. Turn off the UPS if installed.

b.If 900IW403/405 Storage Bins are fitted these must be removed by unscrewing the eight M8x16 screws shown as part 5 in section 10.14.

c.Remove the four screws that secure the power inlet/outlet module to the column (located behind the column).

d.Supply PCB fuses F1, F2, F3, F4 and F5 are located on the back of the Inlet/Outlet Module. Fuse F4 is common to all of the accessories; fuse F1 is for the Electric Elevator Module, fuse F5 is for the outlet socket and fuse F2 and F3 are for other accessories.

e.Replace the power inlet/outlet module including the four retaining screws.

f.Replace 900IW403/405 Storage Bins.

3.5.4Replacement of Printed Circuit Boards.

Refer to photos in section 5.4 for PCB component identification. PCB’s are not repaired, and individual electronic components are not available. Replacement PCB’s are available – refer to section 5.4 for spare part order numbers.

a.Carry out steps a. to d. of section 3.5.2.

b.To remove the control PCB from the front panel disconnect J2 (skin sensor) then release the plastic clips beginning with the ones down the right hand side as viewed from the back.

c.To remove the power PCB from the column disconnect J8, J7, J10, J9 then remove phase and neutral from J5. Unscrew the two 4mm self-tapping screws holding the heat sink to the column.

d.When replacing the power PCBs ensure it is securely held in the column extrusion groove on the right hand side and by the two screws in the heat sink. Ensure that all of the 7 plastic clips/connectors on the control PCB are secure.

e.When replacing the control PCB into the front panel, first remove the control knob (from the front panel) so that it can be re-aligned to the rotary encoder on the control PCB afterwards.

Warmer Technical Manual

3.5.5Replacement of Balance spring (IW910 and IW920 models only)

a.Unscrew plastic locking nut on adjustable pole, and remove upper pole with heater and controller.

b.Remove spring from lower pole.

c.Replace spring and refit upper pole.

3.5.6Replacement of Castors (IW910 and IW920 models only)

a.Grip castor and pull out of mobile base.

b.Push new castor home into castor hole.

3.5.7Replacement of Castors (IW93x and IW95x models only)

a.Lock castor and unscrew from leg.

b.Lock new castor and screw into leg ensuring that the circlip security plate (39) remains positioned over the circlip (14) (refer diagram 8.1.4).

3.5.8Replacement/ Addition of Acetal Side Panel Clips (CosyCot™ models with bassinets prior to version 2.5 only)

Please refer to section 7.6 for part reference details.

a.Follow section 3.5.9 to remove the left-hand corner cap from the side of the bassinet on which changes are to be made.

b.Ensure that the Acetal Side Panel Clip(24) is the correct way up and slide the required number into the rectangular gap located on the inside of the Corner Block (3), positioning it into the groove of the bassinet extrusion.

c.Slide the Side Panel Clip along the Bassinet Extrusion (4) until in the desired location. To access all four sides, all four Corner Caps will need to be removed. Reassemble Corner Cap in reverse order.

NOTE: Too many clips may result in unnecessary force and therefore potential damage to the side panel. To meet IEC 60601-2-21 regulations at least two Acetal clips should remain on each side of the bassinet.

Correct Orientation of the Acetal Side panel Clip (693041413)

Warmer Technical Manual

3.5.9Replacement of Bassinet Corner Caps (IW93x, IW95x, IW960 & IW970 models only)

Refer to Bassinet Assembly diagram 7.3.2

a.Remove all relevant side panels. Unscrew bolt (17) using a 5mm Allen key. For the front two corners the rear handle (10) should be removed from each corner prior to unscrewing bolt (17).

b.When fitting a replacement plastic corner cap (694042167), ensure the two lugs locate under the top surface of the corner block (3). Tighten bolt (17) to a torque of 3Nm.

c.Replace rear handle (10).

NOTE: For version 2.5 and version 3.0 bassinets the corner cap part number is 694042167. For version 2.1 bassinets the corner cap part number is 694042134

For version 2.0 and 1.0 bassinets the corner cap part number is 641040819

3.5.10 Upgrading of Corner Cap Dummy Axles — (CosyCot™ models with bassinets prior to version 2.5 only)

Refer to section 7.2.1 for details of the dummy axle change history. It is advised to replace the corner cap bushes (653040121) at the same time as exchanging dummy axles. The side panel sliding axle will need to be upgraded at the same time as the dummy axle to ensure correct operation. Refer to section 7.2.1 for the correct dummy axle and sliding axle combinations.

a.Follow steps a – c in section 3.5.9 to remove the corner cap.

b.Slide out the two dummy axles in each corner cap and remove the urethane bushes with a pair of pliers.

c.Push a bush halfway into the corner cap before inserting the dummy axle. A thin smear of a silicon grease should be applied to each oval axle stem prior to insertion.

3.5.11Upgrading of Side Panel Sliding Axles

Refer to section 7.2.1 for details of the sliding axle change history. The sliding axles were modified in February 2001 to accept the lengthened dummy axles. All side panels made after this date will work with all versions of dummy axle. If you have an earlier version of the side panels then the sliding axles will need to be changed if they are to be fitted to a new version dummy axle.

a.Remove each side panel from the bassinet

b.Push one of the two sliding axles back to expose the grub screw which retains it. Using a 1.5mm Allen key remove the grub screw and slowly release the sliding axle.

NOTE: The spring force could eject the sliding axle out of the extrusion if it is not securely held.

c.Repeat step b on the other sliding axle and discard both sliding axles.

d.Replace with one of the new sliding axles and use Loctite 272 to secure the grub screw back into the extrusion. Do not wind the grub screw fully in; at least 1mm should be left exposed to ensure the sliding axles are trapped in the slot.

e.Replace the spring and then carefully push the second sliding axle in place and reinstall the grub screw using Loctite 272.

Warmer Technical Manual

3.6Service Procedures – Adjustment

3.6.1Infant Warmer setup procedure for base servicing

a.Disconnect all power and gas from the warmer and remove UPS modules, Side shelves, phototherapy lamps, gas cylinders and any other loose apparatus on the warmer.

b.Push the warmer from the front until the rear castors swivel round underneath the rear legs. Lock the rear castors.

c.Stand behind the column and swing the head over to one side before carefully pulling the warmer column towards you so that the entire warmer pivots on the locked rear castors. Pre-position two chairs or stools in line with the column with one stool close to the base and gently lower the column onto them so that the entire warmer rests on the back of the column and no weight is on the base. Ensure the warmer cannot tip sideways when resting on the chairs/stools.

3.6.2Pre-set Base Height Adjustment (IW93x and IW95x models with preset bases only)

For Warmers Manufactured before February 2004

Preset bases manufactured prior to Feubruary 2004 can have the bassinet height adjusted to 88.4, 97.5 or 101.9 cm (34.8”, 38.4” or 40.1”) by repositioning the lock bar. Refer to Figure 3.6.3 below. Using a 17mm spanner and 6mm Allen key remove the M10 x 30 screw and Nyloc nut (1). Pull both sets of legs together until the desired hole on the lock bar (2) lines up with the hole in the pivot arm (3). Replace the M10 screw and Nyloc nut (1) and fully tighten.

1 2

3

3.6.3 Figure of under side of preset CosyCotTM warmer base Manufactured before February 2004

For Warmers Manufactured after February 2004

Preset bases manufactured after February 2004 can have the bassinet height adjusted to 90.5 or 100.5 cm (35.6”or 39.6”). Refer to Figure 3.6.4 below. Using a 5mm Allen key remove the two M8x25 screws (2). Pull the legs together until the other set of holes on the base adjustment bar (1) line up with the holes on the legs.Replace the M8 screw and fully tighten. There are only two adjustment points for this system.

1

2

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3.6.4Figure of underside of preset CosyCotTM Warmer Base Manufactured after February 2004

3.6.5Base Level Adjustment (IW93x and IW95x models only)

NOTE: Required on warmers with electric elevator bases and preset bases manufactured pre-February 2004. After this date a new preset system means that base level adjustment is not required.

If the base or column are not level, then adjustment of the straight tie rod is required. The straight tie rod is located underneath the base between the centre pivot and the rear legs.

a.Undo the lock nut that secures the straight tie rod to the ball joints.

b.In the middle of the rod is a flat section that should be used for adjustment. Use the 6 mm wrench (part of the tool kit) to turn the rod. One full clockwise turn of the rod (thread M8 x 1.25) will lower the column down by approximately 4 mm. Hence, one full anti-clockwise turn of the rod will lift the column end up by approximately 4 mm.

c.Adjust to level column and base.

d.Tighten the lock nut.

NOTE: When the rod is assembled, the ball joints remaining threaded portions are:

CAUTION A maximum of four full clockwise turns are allowed (remaining threaded portion 5 mm).

3.6.6Castor Angle Adjustment (IW93x & IW95x models only prior to serial No. 9795AEA00436)

If the castor is not vertical to the floor, adjustment of the link arms is required. The link arms are located underneath the leg. Castor angle cannot be adjusted on warmers after the above serial number – refer to PART 13: for serial number identification.

a.Undo the lock nuts that secure the straight tie rod to the ball joints.

b.In the middle of the arm are two holes spaced at 90°. Use a 3mm Allen key or a 3mm bar to turn the arm. One full clockwise turn of the arm (thread M10 x 1.5) will move the castor outwards by approximately 3 mm. Hence, one full anti clockwise turn of the arm will move the castor inwards by approximately 3 mm.

c.Adjust the castor to the vertical position.

d.Tighten the lock nuts.

NOTE: When the arm is assembled the remaining threaded portions on both sides are 13 mm (including 8mm thick lock nuts).

CAUTION A maximum of ten full turns clockwise are allowed (thus the remaining threaded portion will be 10 mm).

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3.6.7Bassinet Clutch Adjustment (IW93x, IW95x, IW960 & IW970 models only)

If the bassinet can be tilted without actuating the rear handle, or pulling the two handles together doesn’t allow tilting of the bassinet, then the bassinet tilt clutch requires adjustment.

Adjustment is performed with the adjuster screw (for fine alterations) or by moving the cable support block (for coarse alterations).

If Bassinet Clutch is too tight (i.e. bassinet can not be tilted):

a.Loosen lock nut on adjuster screw and wind screw out. If screw is already fully wound out then cable support block will have to be moved.

b.Use a 4mm ball ended Allen key to loosen the two grub screws securing the cable support block to the bassinet frame.

NOTE: On version three bassinets (manufactured from November 2002) a single M8 cap screw has replaced the two grub screws, a 5mm Allen key is required to loosen this screw.

c.Wind the adjuster screw approximately half way out.

d.Butt the adjuster screw against the cable sheath by sliding the cable support block towards the rear of the warmer.

e.Fix the cable support block in position by tightening the two grub screws.

f.Move the bassinet tilt brake handle backwards as far as it will go and wind adjuster screw out to take up tension.

g.Tighten adjuster screw lock nut.

h.Pull the bassinet rear handle forwards and check brake release operation.

If Bassinet Clutch is too loose (i.e. bassinet can be tilted without using the bassinet handles):

a.Loosen lock nut on adjuster screw and wind screw in. If screw is already fully wound in then cable support block will have to be moved.

b.Use a 4mm ball ended Allen key to loosen the two grub screws securing the cable support block to the bassinet frame.

NOTE: On version three bassinets (manufactured from November 2002) a single M8 cap screw has replaced the two grub screws, a 5mm Allen key is required to loosen this screw.

c.Wind the adjuster screw approximately half way in.

d.Follow steps d to h above.

If the clutch is still loose the actuator spring can be tightened. Referring to diagram in section 7.12; using a ball ended 4mm Allen key on the M5 screw (part 15) and a 6mm open spanner on the brass actuator (part 12) tighten the spring by winding the screw in. The 12mm washer (part 16) should coincide with a line on the lower tilt link molding (part 7). Cleaning the tilt brake sliders (part 10) with alcohol to remove any particles can also improve the clutch performance.

3.6.8Bassinet Brake Adjustment (For CosyCotTM‘s manufactured after Feb. 2004 with the toothed brake system)

If the bassinet can be tilted without actuating the rear handle, or pulling the two handles together doesn’t allow tilting of the bassinet, then the bassinet brake requires adjustment.

Adjustment is performed with the adjuster screw on the cable:

a.Move the bassinet so that the handle is in the lowest position

b.Loosen the lock nut on the adjuster screw.

c.Wind the screw such that there is 2mm of play in the lower handle (winding it out will reduce the play).

d.Tighten the adjuster screw lock nut.

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3.7Recommended Maintenance Checklist

This sheet can be copied and used to keep a record of the maintenance procedures carried out on your Fisher & Paykel Healthcare 900 series Infant Warmer.

Technician

Technician Signature

Date

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PART 4: Cleaning – Before you begin

WARNING

To avoid the possibility of burns when performing cleaning procedures, ensure the warmer is disconnected from the power supply and the heater element is allowed to cool for one hour.

To avoid the possibility of electric shock hazard when performing cleaning procedures, ensure the warmer is disconnected from the power supply.

If a UPS is installed ensure it is turned off prior to cleaning. Do not remove the UPS shroud during cleaning procedures. Ensure no part of the UPS is immersed in any cleaning agent.

Do not allow liquids to seep into electrical housings.

Do not allow liquids to collect or enter into any oxygen or air fittings or inlets.

Ensure all oxygen and air supplies are turned off and disconnected from the CosyCot™ before performing cleaning procedures. Explosion and fire hazards can exist when performing cleaning procedures in an oxygen-enriched environment.

4.1General Cleaning

• Always follow hospital and local guidelines for cleaning frequencies. Clean the warmer and accessories either weekly or between babies using the following cleaning procedures:

•Before cleaning, remove and discard all used disposable products using the recommended method of disposal.

•Dust all plastic surfaces with a clean damp soft cloth.

•Dust all accessible metal surfaces with a clean soft cloth or paper towel.

• Clean all plastic surfaces with detergent based solution (maximum 2% in water) ensuring the manufacturer’s directions for use of the cleaning agent are followed.

•Alcohol may be used to clean plastic surfaces except for those highlighted black in the diagrams. These contain plastic components made from polycarbonate or acrylic. This includes the entire head assembly, the side panels, the column cap, front panel fascias.

•Ensure no part of the warmer or accessories are immersed in any cleaning agent.

•Apply the cleaning solution with a clean cloth or sponge.

• Clean all parts of the warmer and accessories at ambient conditions. Allow heated surfaces to cool before cleaning for at least 1 hour.

• Dry all surfaces after cleaning with a clean soft cloth or paper towel.

CAUTION

Do not use any compounds containing aromatic hydrocarbons, ammonia, amines or alkaline solutions.

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Chemicals that Attack Polycarbonate

CAUTION

•If your cleaning solution contains any of these compounds then it should not be used on polycarbonate plastics.

•Do not clean the radiant heating element.

•Do not allow excess cleaning solution to seep in between plastic parts where it is difficult to wipe away.

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Warmer Technical Manual

5.2Circuit Overview

Figure 6.2 gives an overview of the IW900 series controller electronics. The location of major components and connectors on the PCB’s are shown in Section 5.4. Full schematics are given in Section 5.5.

5.2.1 IW900 Series Controller Overview

The controller electronics are mounted behind the front control panel on two printed circuit boards (PCBs) — the Control PCB and the Power PCB (see section 5.4 for PCB component photos):

The power PCB provides power supply and I/O lines necessary for sense and control of the examination light and heating element. It holds the mains voltage parts and incorporates a heat sink. The power PCB is connected to the control PCB by a single 14-way ribbon cable (J3). Also connected to the Power PCB are the power transformer (J10 and J9), the heater, light and thermal cut-out harness (J7 and J8), the power switch (J13 and J6) and the mains input terminals (J5).

The control PCB is based around the Phillip’s 80C552 microcontroller. It provides a user interface, temperature measurement and intelligent control of the element power. Almost all of the warmer functions are implemented in software. The control PCB is connected to the Power PCB (J1), the skin sensor socket (J2) and the serial communications port (J12).

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5.3Circuit Description

5.3.1Software Independent Safety Circuits

Five safety features are included which function independently of the micro-controller. These safety features are provided in addition to the safety features already provided by the micro-controller software.

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5.3.2Software Controlled Circuits

The remaining circuit components are used in conjunction with the micro-controller software:

PITCH & VOLUME CONTROL BUZZER U19 provides pitch and volume control over buzzer PZ1 which plays all alarm and acknowledge sounds.

ZERO CROSSING & LINE LEVEL SENSE The mains voltage is monitored by a secondary winding from the power transformer. Comparator U14E detects zero crossings and a waveform is derived (found at test point TP14) which exhibits a momentary negative going pulse on each zero crossing. A DC voltage proportional to line voltage level is detectable at TP8.

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5.4PCB Component Locations

The photographs below identify some of the major components used on the IW900 series of Infant Radiant Warmers and where they are located.

5.4.1Power PCB Board

NOTE: These are voltage specific with the voltage identified by a label on the mains isolating relay.