Cardiette AR2100 Service manual

ar2100 adv

service manual

english

This Service Manual has been prepared with the objective of giving the user all the information necessary to obtain the best use
of the cardiette

General information

et medical devices SpA, continuously in search of technological improvement and customer satisfaction, reserves the right to

modify this publication without prior notice at any time.

All rights reserved © et medical devices SpA ITALY.

®

ar2100 adv.

sm_00119_ar2100 adv _01_eng Rev. 00/CS/CF/AA 23/05/2003 Ref: : 66500119

2

Contents

1 Introduction 5

1.1 Particular recommendations and warnings 6

2 Description of the device 7

2.1 Mother board 7

2.2 Battery 7

2.3 Keyboard card 7

2.4 Printer unit 7

2.5 IR Module (RS232) 7

3 Inputs and outputs 8

3.1 Connection to the patient input port 8

4 Testing the safety characteristics 9

4.1 Leakage currents test 9

5 Testing the main technical characteristics of the electrocardiograph 10

5.1 Instruments necessary: 10

5.2 Sensitivity test 10

5.3 Testing the ECG leads 10

5.4 Testing the paper feed rate 11

5.5 Frequency response test 11

6 Functional blocks 12

6.1 Mother board 12

6.1.1 Processor 12

6.1.2 Battery charger 12

6.1.3 Internal circuit power supply 12

6.1.4 ECG acquisition 12

6.1.5 Motor control 13

6.1.6 Input/output circuits 13

6.2 Battery 13

6.3 Keyboard card 13

6.4 Printer unit 13

6.5 IR Module 14

7 Trouble Shooting 15

8 How to dismantle and reassemble the device 16

8.1 General precautions 16

8.2 Opening and closing the device (table T3) 16

8.3 Removing the mother board (table T5) 16

8.4 Removing the battery (table T4) 16

8.5 Removing the keyboard card (table T5) 16

8.6 Removing the print unit (table T7A, T7B) 16

8.7 Removing the print unit thermal head (table T7B) 16

8.8 Dismantling the paper guide door (table T1) 17

8.9 Dismantling and replacing the keyboard membrane (table T1) 17

9 Calibration and setting 18

9.1 General information 18

9.1.1 Self-test 18

9.1.2 Mark calibration 18

9.1.3 Speed calibration 18

9.1.4 Metres of paper printed 19

9.1.5 Firmware upgrades 19

10 Periodic maintenance 20

10.1 Inspection frequency 20

11 Cleaning and disinfection 21

3

Cleaning the device, electrodes and patient cable 21

11.1

11.2 Clean thermal head 21

11.3 Cleaning the paper guide roller 21

11.4 Cleaning the mark recognition sensor 21

12 Spare parts list 22

13 Interconnections with medical systems 23

14 ECG ar 2100 adv technical characteristics 24

15 APPENDIX A 26

15.1 Procedures for manipulating and storing components (ESD) 26

16 APPENDIX B 27

16.1 Figures and illustrated tables 27

17 Revision Sheet 28

4

1 Introduction

ar2100 adv epitomises the reliability, modularity, versatility and capacity to be updated which
characterise the latest generation of cardiette

®

electrocardiographs.

ar2100 adv is a portable electrocardiograph with dual power supply, (mains and rechargeable internal
batteries), which in the basic configuration will:

! -record an ECG exam in automatic or manual mode;

! reproduce the ECG signal on 210 mm paper in 3-6 12 channel format thanks to the high resolution

thermal printer;

! storage of the most recent recording in automatic mode and print additional copies.
*In just a few minutes, your ar2100 adv can be equipped with:

! “memory option”: to store up to 40 full ECG exams, with no need to print out immediately on paper

(“paper saving” mode);

! "ECG measurements option": automatic ECG parameter measurement program;

! "ECG signal interpretive option": a useful and dependable diagnostics support provided by the “HES”

program;

! "arrhythmia option": program enabling detection of arrhythmia events during continuous recording;

! “HRV analysis option”: program enabling detection of variations in heart rate;

! "L.E.M.S - PC archive option": to store the exam to archive on a Personal Computer running “L.E.M.S.”

(Local ECG Management System) software;

! "R.T.E. - PC-ECG option": for real time display of the twelve leads on your computer screen to allow

management of patient medical records and archiving of exams in digital format using " R.T.E" (Real
Time ECG) software. R.T.E has an optional "HES" module for automatic interpretation of the ECG
signal.

* By updating the firmware. Contact your distributor for further details.

5

1.1 Particular recommendations and warnings

! This service manual is for the use of competent technical staff only.

! Always use the equipment according to the instructions in this manual.

! The device is equipped with a set of standard accessories. For reasons of safety, reliability and conformity with

the Medical Devices Directive 93/42/EEC, use only original accessories or accessories approved by the
manufacturer.

! The device is equipped with a special long-life thermal head writing system, which allows maximum writing

precision. To avoid frequent and costly replacements and repairs, always use the original paper or paper
approved by the manufacturer. The manufacturer will not accept liability for any damage to the device or any
other adverse effect caused by the use of unsuitable paper.

! Do not subject the device to impact or excessive vibrations.

! Do not allow liquids to penetrate inside the device. If this should accidentally occur, have the device tested by

an Authorized Assistance Centre to verify its functional efficiency, before using it again.

! Make sure that the value of the supply voltage corresponds to that indicated on the data plate of the device.

! If you are using the device in connection with others, ensure that: all connections are made by skilled persons;

all connections comply with safety regulations; all other devices connected respond likewise to regulations.
Non-compliance with these regulations can cause physical harm to the patient connected and to the person
operating the device. Should it be difficult to obtain the necessary information for assessing the risk of the
individual connections, apply directly to the manufacturers concerned or avoid making the connections.

! In the event of other equipment being connected directly or indirectly to the patient, check for the possible

risks caused by the sum of the leakage currents on the body of the patient.

! The device is protected against defibrillation discharges in accordance with IEC standard 601-1-25; to ensure

that the signal is restored, use only original electrodes or electrodes responding to IEC and AAMI standards.

! If an electrosurgical scalpel is in use, the patient cable should be disconnected from the device.

! In any event, the greatest care should be taken when using defibrillators or high-frequency surgical devices at

the same time as the ECG. If you have any doubts while using such devices, disconnect the patient from the
electrocardiograph temporarily.

! The device recognizes the impulses generated by a pacemaker and does not interfere with its operation, as

prescribed by standards in use at the time of drafting this manual.

! Avoid exposing the equipment to extreme temperatures, excessive dust or dirt, and very salty or damp

environments; observe the ambient conditions described in detail under the "Technical specifications” heading.

! Periodically check the efficiency of all accessories and of the device itself. Use the built in test function to

perform an initial efficiency check. Contact the Authorized Assistance Centre whenever the device seems to be
operating irregularly.

! To prolong the life of your ar2100adv, have it periodically checked at an Authorised Assistance Centre

! Warning: do not use the device in the presence of anaesthetics or volatile gases!

! Warning: the indications obtained using automatic interpreting programs or other diagnostic aids must be

reviewed and countersigned by a qualified medical person!

! Warning: the device is provided with an IR interface for the transfer of data to other devices. The IR interface

must not be masked , even accidentally, as this will adversely affect its capability and its operation,
interrupting and preventing the correct flow of data.

! Warning: Environmental protection: When no longer in use the device must be disposed of according to local

regulation, do not dispose as ordinary refuse.

! The manufacturer will acknowledge liability for the safety, reliability and functional efficiency of the device only

if:

• modifications and repairs are performed by the manufacturer or by an Authorized Assistance Centre;

• the a.c. mains power supply of the premises in which the device is used corresponds to current

regulations;

• the device is operated according to user instructions;

• any accessories in use are those approved by the manufacturer.

6

2 Description of the device

The device consists of the following basic elements:

2.1 Mother board

This is a “Fine line” multilayer printed circuit board for mounting SMD components.

It houses most of the electronic circuits of the device.

2.2 Battery

Lead battery.

2.3 Keyboard card

The keyboard card consists of the device functional keys and LED/display messaging devices.

2.4 Printer unit

This consists of the thermal printer head support and the mechanical elements required to position it correctly.

2.5 IR Module (RS232)

The function of the IR module is to transmit and receive data from an external PC.

7

3 Inputs and outputs

Direct connections from the ar2100 adv to external equipment may only be made using the IR serial port, not by
cable.

3.1 Connection to the patient input port

8

7

15 9

Port from connection side

5

6

1314

12

Pin 1 = IN C2 (electrode C2)
Pin 2 = IN C3 (electrode C3)
Pin 3 = IN C4 (electrode C4)
Pin 4 = IN C5 (electrode C5)
Pin 5 = IN C6 (electrode C6)
Pin 6 = AGND (analogue ground)
Pin 7 = NC
Pin 8 = DGND (digital ground)
Pin 9 = IN R (electrode R)
Pin 10 = IN L (electrode L)
Pin 11 = IN F (electrode F)
Pin 12 = IN C1 (electrode C1)
Pin 13 = NC (non connected)
Pin 14 = IN N (electrode N)
Pin 15 = NC (non connected)

4

3

10

11

1

2

8

4 Testing the safety characteristics

The safety regulations envisage two important tests:

! The leakage currents test measures the value of the currents lost in relation to the safety of the patient and

the operator.

Warning: All safety tests must be performed according to standards EN.60601-1(1990 paragraphs 19 - 20) EN 60601-2-25
(1995) unless otherwise specified in the local safety regulations.

4.1 Leakage currents test

Warning: This test must be performed every time the device has been opened for inspection and/or repair, and in any event

every two years, unless otherwise specified by the local safety regulations.

Connect the electrocardiogram to the battery charger, and then connect this assembly to the measuring
instrument according to the instrument’s manual, recalling that:

1) The leakage current to the casing is measuring between the mains supply circuits and a metal sheet no
greater than 20 x 10 cm pressed against the casing of the device.

2) The leakage current in the patient is measured between the mains and the applied part. For connection to the
applied part use the patient lead itself.

3) The leakage current in the patient with mains voltage directly on the applied part (first failure condition) is
measured between the meta sheet connected to the device and the applied part.

4) The auxiliary current in the patient is measured singly on each electrode (excluding the reference electrode)
compared to all the other electrodes connected together.

Note: Make the measurements following the indications in the instrument user manual, and check that the leakage current
values measured are less than or equal to those listed in table IV.

Table IV.

Admissible permanent values for leakage and auxiliary currents in the patient in mA (milliamperes).

Current path

N.C. S.F.C.
Leakage current to earth 0.5 1
Leakage current in case 0.1 0.5
Leakage current in the patient d.c – a.c. 0.01 0.05
Leakage current in the patient
(mains voltage in applied part)
Auxiliary current in patient d.c – a.c. 0.01 0.05
N.C. = Normal condition
S.F.C. = First failure condition

----- 0.05

CF type

9

5 Testing the main technical characteristics of the

electrocardiograph

Warning: All tests must be performed in compliance with the provisions of the related general, detailed and performance safety
regulations listed in the technical characteristics section

5.1 Instruments necessary:

a) sample mV generator with the following characteristics:

b) low frequency sine wave generator;

c) ECG simulator.

5.2 Sensitivity test

! set the device up to record 6 channels on leads V1 to V6 with sensitivity of 20 mm/mV;

! connect the patient cable to the device;

! connect terminals C1 ! C6 of the patient cable connected to the device to the positive pin of instrument

5.1.a);connect all the other cable terminals to the negative pin of instrument 5.1 a);

! record the signal for a few seconds;

! check that the amplitude of the recorded signal is 20mm. +/- 5% on all channels.

5.3 Testing the ECG leads

! switch the device on;

! connect the patient cable to the device;

! connect the red termination of the patient cable to the positive pin of the instrument specified in point 5.a.a

and the remaining wires to the negative pin.

! start recording and check that the amplitude in mm of the signal, and its polarity (positive or negative) comply

with the values indicated in table 5.3.

! repeat the measurements in sequence with the remaining active terminations G - V - C1 - C2 - C3 - C4 - C5 -

C6 of the patient cable using the method described in c), and check that the values correspond to those
indicated in table 5.3.

PATIENT CABLE AND LEADS TEST

CONNECTIONS FOR THE TEST

INSTRUMENT PATIENT CABLE CONNECTIONS

Connector Patient cable terminations N. 1 Termination to positive apart from black

+ "

- "

Square wave signal from: Electrocardiograph: amplification 1mV/10mm

1 Hz ± 1% 1 mVpp ± 3%

①
② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ⑩

N. 4 Terminations to negative with 5 wire cable

N. 9 Terminations to negative with 10 wire cable

signal recorded in mm ±5%

TABLE OF VALUES

Term.

to

positive

R - 10 - 10 0 + 10 - 5 - 5 - 3.3 - 3.3 - 3.3 - 3.3 - 3.3 - 3.3
G + 10 0 - 10 - 5 + 10 - 5 - 3.3 - 3.3 - 3.3 - 3.3 - 3.3 - 3.3

V 0 + 10 + 10 - 5 - 5 + 10 - 3.3 - 3.3 - 3.3 - 3.3 - 3.3 - 3.3
C1 0 0 0 0 0 0 + 10 0 0 0 0 0
C2 0 0 0 0 0 0 0 + 10 0 0 0 0
C3 0 0 0 0 0 0 0 0 + 10 0 0 0
C4 0 0 0 0 0 0 0 0 0 + 10 0 0
C5 0 0 0 0 0 0 0 0 0 0 + 10 0
C6 0 0 0 0 0 0 0 0 0 0 0 + 10

I° II° III° aVR aVL aVF V1 V2 V3 V4 V5 V6

mm mm mm mm mm mm mm mm mm mm mm mm

LEADS AND VALUE OF IMPULSE

Table 5.3

10

5.4 Testing the paper feed rate

! switch on the device and connect the patient cable;

! connect terminals C1 ! C6 of the patient cable to the positive pin of instrument 5.1.a);

! connect all the other cable terminals to the negative pin of instrument 5.1 a);

! using the instrument with a square wave of 1 Hz and an amplitude of 1 mVpp;

! record the signal on leads V1 ! V6;

! measure the length of the wave cycle recorded on the paper.

The results should be as follows:

Period = 50 mm +/- 5% for a feed rate of 50 mm/s;

Period = 25 mm +/- 5% for a feed rate of 25 mm/s;

Period = 5 mm +/-10% for a feed rate of 5 mm/s;

5.5 Frequency response test

! switch on the device and connect the patient cable;

! connect terminals C1 ! C6 of the patient cable to the positive pin of instrument 5.1.a);

! connect all the other cable terminals to the negative pin of instrument 5.1 a);

! set the sine wave generator to 10Hz with an amplitude of c. 1mVpp;

! select leads V1 ! V6 and a sensitivity of 10 mm/mV.;

! make a recording and adjust the amplitude of the generator so as to obtain a 10 mm excursion of the signal

recorded;

! vary the generator frequency from 0.5Hz to 100Hz with constant amplitude;

! check that the frequency response is in accordance with the values in table 5.5.

Amplitude of signal in

mVpv

1 From 0.67 to 40

1 From 40 to 100 + 10% - 30%

Unfiltered sinusoidal

input signal in Hz

Relative tolerance of

signal

10 Hz – 10 mm

± 10%

0,5 From 100 to 150 + 10% - 30%

Table 5.5

Note: The 0.5 Hz pitch linear phase anti-drift filter is always on and cannot be switched off.

The 50 or 60 Hz filter eliminates modified notch digital type mains disturbances in the linear phase, with a
frequency response of 32 Hz - 3dB.

11

6 Functional blocks

6.1 Mother board

The motherboard is based on the following principal components:

6.1.1 Processor

! 32 bit Fujitsu MB91101 RISC microprocessor with 12 MHz clock, 2 x 8 Mb flash memories installed.

! These memories house:

! boot code;

! operating system software;

! applications software;

! calibration data;

! ecg archive.

! The device also has 2 x 4 Mb static rams.

Testing the mother board circuits

! Execution of ram self test.

6.1.2 Battery charger

The battery charger section consists of the following parts:

! Autosense AC mains adapter circuit, 230/115Vac, out 22 Vac, fuse protected, and PTC protection against

overheating.

! Mains filter against electromagnetic disturbances.

! Rectification, voltage stabilisation and current limitation circuits.

Testing the battery charger circuit (see sheet 9 el diag)

! If the mains on led does not light up, check using the following procedure:

! Disconnect the mains cable;

! Check the externally accessible mains fuses;

! Disconnect the battery from the device as indicated in chapter 8.4;

! Connect a voltmeter to the free terminal caps;

! Connect a 1000 Ohm resistance in parallel with the voltmeter;

! Connect the mains cable: the reading should indicate a voltage of 13.65 Vdc± 5%;

! If the reading is outside the range of values indicated, replace the motherboard.

6.1.3 Internal circuit power supply

This consists of the following power supplies:

! +5 V generated by a switching type voltage regulator;

! 5 VI – VL to supply the patient input analogue circuits on the hybrid circuit (insulated part);

! + 3.3 V generated by a linear regulator to supply the control logic;

! + 3 V reference voltage for the A/D converter;

! VTPH voltage obtained from the battery to supply the thermal head. This voltage is limited to a current of 5A

and stabilised in voltage at +26 Vdc enabled only when printing.

Testing internal circuit power supplies (ref sheet 3 el diag)

! Check fuse F1;

! If no power is supplied to the internal circuits, replace the motherboard.

6.1.4 ECG acquisition

This consists of the following parts:

! Patient input connector;

! Protection against defibrillator discharges;

12

! Signal polarisation circuit;

! Hybrid circuit for amplification, filter and clamp;

! 12 bit Ad converter, 5 microvolts per bit;

! Insulation photocoupler (double insulation).

6.1.5 Motor control

This consists of the following parts:

! Stroboscopic sensor control;

! Phase comparator between reference frequency and motor feedback;

! Current amplifier for motor power supply.

6.1.6 Input/output circuits

6.2 Battery

Lead battery

! The battery is protected against short circuits by a Pico SHF T5A fuse, voltage 12 Vdc, and capacity 2000 mAh,

supplied by the manufacturer of the device.

! Complete recharging requires at least 24 hours or longer. The battery can be partially recharged, in this case

to prolong the life of the battery it should be fully discharged and recharged every 2 months.

! Replace the battery with one of equivalent type, voltage and capacity.

Warning: The battery must only be removed if the device is off and the mains supply cable disconnected. Do not dispose of a
spent battery as ordinary refuse or litter.

Note: The operation of the device is not guaranteed if the battery is flat or missing.

Note: The configuration parameters and any stored ECGs are not lost when the battery is changed.

Note: Update the system date and time after replacing the battery.

Battery check

Proceed as follows to check the efficiency of the battery:

! Leave the battery on charge for at least 24 hours;

! Disconnect the mains cable;

! Activate printing of an ECG in manual mode on 6 channels at 5 mm/s: if the device shows the battery is flat

within the first 5 minutes the battery should be replaced.

6.3 Keyboard card

The keyboard consists of:

! 13 function keys;

! 32 alphanumeric keys;

! 1 mains on LED;

! 128 x 32 pixel graphic display LCD;

! CPU connection through bi-directional synchronous serial port.

Testing the keyboard card circuits

! Execution of keyboard self-test;

! Execution of display self-test;

6.4 Printer unit

This consists of the thermal printer head support and the mechanical elements required to position it correctly.

! 1728 dot high resolution printer head, 8 dots per mm;

! support;

! paper feed unit consisting of 2 direct current reduction gears connected in parallel, one of which equipped with

stroboscopic speed control;

! mark detection sensor.

13

Testing the print unit

! Execution of printer self-test.

6.5 IR Module

! The function of the IR module is to transmit and receive data from an external PC. The IR module can be used

to perform the following functions:

!

Updating firmware (Loader)*;

!

Batch ECG transmission (L.E.M.S.)*;

! Real time ECG transmission (R.T.E ir)*.

* Consult the specific manual for further information.

14

7 Trouble Shooting

Defect Possible cause/symptom Remedy

The device does not switch on in any
mode.

The device does not switch on when
in mains mode.

The device does not switch on when
in battery mode.

The battery does not charge. • The device has not been charged

Keyboard keys not working.. • The key pressed not enabled for

The paper feeds through without
printing.

Anomalous printout. • Clean thermal head.

Does not print automatically or does
not paginate the trace correctly.

Paper feed defective, or paper
finished message with paper present.

EC signal disturbed or anomalous. • Error message on display, on

The device stops during use.

• Mother board/keyboard card. • Holding down the ON/OFF key,
measure 12Vdc on J52
(keyboard connector) pin 3; if
absent replace the keyboard
card, if not, replace the
motherboard.

• Mains LED indicator off. • Check mains fuses, if OK replace
motherboard.

• Check T5A fuse on motherboard.

• Check efficiency of battery and
replace if necessary.

• Leave the device charging for at

for long enough.

• Mains LED indicator off.

• Defective battery.

the specific function.

• Paper not suitable, without black
page recognition mark.

• Paper not suitable, without black
page recognition mark.

• Check paper guides are not

printout.

• No functions operational, no
commands accepted.

least 24 hours.

• Check mains fuses, if OK replace
motherboard.

• Check efficiency of battery and
replace if necessary.

• Check T5A fuse on motherboard.

• Execute keyboard self test and if

it fails replace keyboard card.

• Check that original paper is
being used.

• Check the paper has been
inserted correctly.

• Check that the 26 Vdc VTPH
power supply to the thermal
print head is present when
printing is active, if not, replace
the mother board.

• Check signals on test point table
T8 are present. If good, replace
thermal head unit, otherwise
replace motherboard.

• Execute printer self-test, replace
thermal head unit if some dots
are missing.

• Clean mark sensor

• Perform mark sensor calibration.

• Replace print unit.

damaged.

• Clean rubber roller

• Replace print unit.

• See user manual.

• Press reset button on right side

of device.

15

8 How to dismantle and reassemble the device

8.1 General precautions

Disconnect the mains cable before opening the unit.
See chapter 15 (procedures for handling ESD components).
To reassemble the device, perform the operations described below in reverse order, ensuring that all
subassemblies and connections are performed correctly.

8.2 Opening and closing the device (table T3)

! Remove the 9 fixing screws from the mobile base (T3 Ref. 1);

! Lift the mobile base of the device;

! Disconnect the two battery connections;

! Remove the lower mobile part.

Warning: Respect the correct polarity of the battery connection: if the polarity should be inverted check the Pico SHF T5A fuse
on the motherboard.

8.3 Removing the mother board (table T5)

! Proceed following the instructions in chapter 8.2;

! Remove 2 screws (T5 Ref. 1);

! Lift the patient connector side of the board and disconnect the following:

• the keyboard flat;

• the thermal head flat;

• the motor and mark sensor card flat;

• the earth connector.

Warning: Replacing the motherboard means that the paper feed speed and mark presence sensor must be recalibrated.

8.4 Removing the battery (table T4)

! Proceed following the instructions in chapter 8.2;

! Remove the 2 screws attaching the battery to the housing (T4 Ref. 1);

! Remove the battery support (T4 Ref. 2);

! Remove the battery and replace.

8.5 Removing the keyboard card (table T5)

! Proceed as described in chapter 8.2.

! Remove 8 screws (T5 Ref. 3);

! Replace the keyboard card.

8.6 Removing the print unit (table T7A, T7B)

! Proceed as described in chapter 8.3.;

! Remove 2 screws (T1 Ref. 1);

! Remove 2 screws (T6 Ref. 1);

! Remove the print unit from door side.

Warning: Replacing the print unit means that the paper feed speed and mark presence sensor must be recalibrated.

8.7 Removing the print unit thermal head (table T7B)

! Proceed as described in chapter 8.6.

! Remove 2 screws (T7B Ref. 1);

Warning: The thermal head is extremely sensitive to electrostatic potentials and the work procedures described in appendix A
should be closely followed. The thermal head is aligned in the factory and requires no further calibration.

16

8.8 Dismantling the paper guide door (table T1)

! Proceed as described in chapter 8.2.

! Loosen the 2 clamp screws (T5 Ref. 2);

! Position the paper guide door in a vertical position and remove the 2 locking nuts from the studs (T1 Ref. 2),

remove the studs;

! Replace the paper guide door.

Warning: tighten the 2 screws (table T5 Ref. 2)until fully tight, then unscrew one turn.

Note: If the roller is not clean and the paper door is on or incorrectly locked, the paper feed will not operate properly and the

device will malfunction.

8.9 Dismantling and replacing the keyboard membrane (table T1)

The keyboard membrane (T1 ref. 3) is an elastic membrane over the keyboard card that allows the keys to be
pressed.
This self-adhesive plate is glued to the upper part of the device.
To replace it when worn, lift one corner with a sharp blade and tear off the case.
Remove any adhesive left on the case.
To fit a new membrane, centre it with the corners in its housing, and press lightly over the whole surface, ensuring
the display protection window is correctly positioned.

Note: A broken or cracked keyboard membrane compromises the safety of the device.

17