Welch Allyn GSI 17 User manual

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Covers Welch Allyn AM232 Manual Audiometer

Operation Manual

Warranty

We, Grason-Stadler, Inc. warrant that this product is free from defects in material and workmanship and, when properly installed and used, will perform in accordance with applicable specifications.

meet this standard, it will be repaired, or at our option, replaced at no charge except

for transportation costs, when returned to an authorized Grason-Stadler service facility.

If field service is requested, there will be no charge for labor or material, however, there

will be a charge for travel expense at the service center’s current rate.

If within one year after original shipment it is found not to

NOTE

Changes in the product not approved in writing

Grason-Stadler shall void this warranty. Grason-Stadler shall not be liable for any indirect, special or consequential damages, even if notice has been given in advance of the possibility of such damages.

THIS WARRANTY IS IN LIEU OF ALL OTHER

WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT

NOT LIMITED TO, ANY IMPLIED WARRANTY OF

MERCHANTABILITY OF FITNESS FOR A PARTICULAR

PURPOSE.

GSI

Grason-Stadler

A Welch Allyn Company

Grason-Stadler, Inc.

1 Westchester Drive

Milford, NH 03055-3056

Telephone: 603-672-0470

Fax: 603-672-0487

Service

Manual 1717-0110,,

Printed January, 1991

Printed April, 1991 Printed January, 1992 Printed January, 1994

(#1)

(#2)

(#3) (#4)

Rev.

Warranty

Table of

Warning

...........................

.L.

..............................

Key to Symbols Used on Schematics Foreword

...........................

SECTION 1- PRODUCT SPECIFICATIONS

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

1.10

1.11

1.12

1.13

1.14

1.15

1.16

1.17

1.18

Catalog Listings Standards

.....................

Test Stimulus

..................

Output Hearing Level Controi Signal to Noise Ratio Tone Switch Stimulus Transducers Front Panel

....................

......................

................

Controls/Rear Power and Power Line Battery Pack Voltage

...............

................

Environmental Conditions Mechanical Dimensions Material Used in Leakage Test

Manufacture

....................

Headband Static Force

..............

...............

Earphone Cushion Attenuation

Accessories

....................

..............

............

Panel Connectors

..............

............

.....

: : 1

iii

vii

viii

1 1 1 2 2

3 3 5 5 5

6 6 6 6 6 7

SECTION 2

FUNCTIONAL DESCRIPTION

Figure 2-l:

2.1

2.2

2.3

2.4

2.5 SECTION 3

3.1

3.2

3.3

3.4

Front Panel Controls and Indicators Rear Panel Connectors and Controls General Operation of Controls

Power Up Initialization

Sleep Mode

ROUTINE MAINTENANCE

Earphone Cords

Hum and Random Distortion and Special Messages

3.4.1 CAL

3.4.2

Exx

Connectors, Controls, Indicators

........

.........

...........

..............

.....................

..................

Noise

Frequency Shift

..........

.......

..................

...

: :

........................

. . .

iii

9 10 10 10 11

13 13

13 14 14 14

SECTION

4- CALIBRATION

4.1

4.2

4.2.1

4.2.2

4.3

4.4

4.5

4.5.1

4.5.2

4.5.3

4.5.4

4.5.5

4.5.6

4.5.7

4.5.8

4.5.9

4.5.10

4.5.11

4.5.12

4.6

4.7

4.8

4.8.1

4.8.2

4.8.3

4.8.4

4.9

4.9.1

4.9.2

4.9.3

4.9.4

4.9.5

Quick Reference Calibration Figure 4-l: Figure 4-2: Table 4-l: Calibration Mode Operation

Quick Reference Calibration Control; Access to Calibration Controls Calibration Reference Threshold;

...........................

..........

....

Cal/Normal Switch Calibration Mode Dip Switches Calibration Mode Entry Mode Initialization Earphone SPL Tone Type Switch

Calibration Mode

..................

...............

............................

............

Routing Switch Frequency Selector' Present Bar

HLl

Extended Range

.....................

...

Pushbution

Response Switch

HLDisplay

Response LED

Stimulus ON

.....................

....................

.....................

Low Battery Segment

"+"

LCD Segment Calibration Mode Exit Calibration Data Storage and Validation

Calibration Mode Dip Switch Dip Switch S4 Dip Switch S3 Dip Switch S2 Dip Switch

....................

Selection of the Diagnostic Mode Hardware Diagnostic Test (DO) Pushbutton Diagnostic Test

..................................

................................

...................

.................

...................

................

.............

............

(D1)

.......

..........

...........

Display Diagnostic Test (D2) A/D Converter Diagnostic Test Attenuator Maximum Output Level Calibration

(D3) 1

(D4) .

: : 1 : 1 1 : :

: :

17 18 19

19 19 20 21 21

2";

22 22 22

23 23

23 24 24 25 25 25 27 27

29 31 33

SECTION

Figure 5-l:

5.1

Disassembly Instructions

5.2

5.3 SECTION

Accessories and Replacement Parts

6.1 Diagnostic Mode (DO)

6.2

6.3

DISASSEMBLY

Disassembly

Parts Numbers

TROUBLESHOOTING

....................

..............

..........

Troubleshooting Using the Hardware

............

Figure 6-l:

Diagnostic

Functions Output Related Figure 6-2:

Troubleshooting Block Diagram of Amplifier Signal Flow

Left or Right Amplifier Troubleshooting Symptoms'

Mode

Controls and

..................

Symptoms

...

.......

45 46

48 48

FOREWORD

GENERAL SERVICE INFORMATION Operating,

can be found in the Instruction Manual (1717-0100). and/or bench testing of GSI 17 Audiometers should only be performed by trained personnel. The following instructions are provided primarily for use by persons who are skilled in the

repair of electronic equipment. CMOS HANDLING PRECAUTIONS Many of the integrated circuits on the P.C. boards are CMOS and

NMOS type.

Failure to observe the following precautions whenever a circuit board or an integrated-circuit package is handled can result in damage to the GSI 17.

Place instrument and parts on a grounded, conductive work surface.

Ground yourself (with a strap having about 1 M ohm resistance).

Ground the frame of any test instrument or soldering iron to

be used.

check-out procedures,

CAUTION

trouble-shooting hints, etc.,

Repair

If any circuit boards are

enclose them in conductive (anti-static) envelopes.

to be stored or transported,

SECTION 1

._-

Product Specifications

1.1 CATALOG LISTINGS

1717-9700

1717-9710 GSI 17 Audiometer, 1717-9705 GSI 17 Audiometer, AC Power (Export) 1717-9715 GSI 17 Audiometer,

1.2 STANDARDS

This unit is a single channel,

is equipped with pure

conduction transducers (TDH39 Earphones). ANSI S3.6 and IEC 645 Type 4 Audiometer Standards.

The GSI 17 is designed to meet current revisions of the following

standards and specifications for audiometers:

GSI 17 Audiometer, AC Power (USA)

AC Power and Battery (USA) AC Power and Battery (Export)

pure tone screening audiometer.

tone stimulus signals, and air

This instrument meets

ANSI S3.6

IEC 645 IS0 389 IEC 601

1.3 TEST STIMULUS

PURE TONE SPECIFICATIONS A pure tone is the only stimulus source for this audiometer.

DISCRETE FREQUENCIES 125, 250,

FREQUENCY ACCURACY

< +3%

TOTAL HARMONIC DISTORTION (FROM 125 ACOUSTICALLY)

500, 750, 1000, 1500, 2000, 3000, 4000, 6000, 8000 Hz

Frequency

125Hz 1000 3000

Hz Hz

Test

100

Hz TO

4000 Hz, MEASURED

<2%

1.4 OUTPUT HEARING LEVEL CONTROL

CALIBRATED IN dB MEASURED IN INCREMENTS OF 5

RANGES

-10

125

Hz 500to 250

6000

and

Additionally A

Hz -10

8000

"+10 dB""

-10

Extended Range

maximum HL at all frequencies by 10 ACCURACY OF ALL SETTINGS

125 to 4000 Hz

6000 to 8000 Hz

1.5 SIGNAL TO NOISE RATIO (IN

>70

dB measured acoustically in dB HL

1.6 TONE SWITCH

This

electronic

switch turns the stimulus

HEARING LEVEL CONTROL:

+5 dB

1/3

dB.

OCTAVE)

minimal audible distortion.

dBB

HL Switch,

which

signal

extends

ON/OFF with

MODES

Normal State: Activated State:

Stimulus OFF Stimulus ON

RISE/FALL TIME

20-50

Measured at the -1 dB and

-20

points on the signal envelope.

ON/OFF RAT IO

With

the

Tone Switch OFF,

below standard reference equivalent threshold for any

the output will be at

least

1/3

-10 octave

dB band with HL setting of 60 dB or below. ABOVE 60 dB HL SETTING

>70

dB CROSS CHANNEL LEAKAGE At HL settings of 70 dB or greater,unwanted signals in the

non-

test earphone shall be at least 70 dB below the tone in the test

earphone.

dB2

1.7 STIMULUS TYPES

Continuous Tone Continuous FM Tone Pulsed Tone

SIGNAL FORMAT Continuous Pulsed

Pulsed Rate:

Signal steady as long as Present Bar is depressed.

2.5

Pulses/sec Pulse rate is synchronized to the "Present first and last pulse will have 200 ms on time.

DUTY CYCLE

50%

RISE/FALLTIME

20-50 ms

ON/OFF RATIO (BETWEEN PULSES)

>20

FREQUENCY MODULATION

FM Rate: FM Deviation:

5 Hz

25%

Bar"

so that

the

1.8 TRANSDUCERS HEADSET TDH39 Earphones with 60 ohm impedance

1.9 FRONT PANEL CONTROLS AND REAR PANEL CONNECTORS

FRONT PANEL

CONTROLS

Frequency Selection HL Select Mode Selector (Pulsed/Steady/FM) Routing (Left/Right) Present Bar Power Switch

"+10 dB"

Push-Button

INDICATORS:

Power ON/OFF Frequency Selector dB

HL - LCD Left/Right Earphone Pulsed/Steady/FM

Subject

"Battery

Response - LED

Low"

(when applicable, i.e. Battery Option

purchased) - LCD Tone ON - LED Extended Range - LCD

REAR PANEL CONNECTORS

Left and Right Earphone -

Subject Response Switch

- 1/4"

Power Cord- 5 Pin DIN

LEFT AND RIGHT EARPHONE JACKS Pin#

Tip Sleeve

SUBJECT SWITCH

--Pin&

Tip Sleeve

POWER INPUT

Function

Phone High

25 u VRMS to 2.5 VRMS

Phone Low

(J7)

Function

Switch High Switch Low

(J1)

Battery Power No Power Module

Pin #

Name

Attached

1/4"

Phone Jack Phone Jack

(J4 & J5)

Output Voltaqe

0 Volts

Output Voltaqe

Vdc

0 Volts

Power Module Connected w/NiCad Battery

Installed

Impedance

(max)

130 ohms

0 ohms

Impedance

47 K ohms

Power Module Connected w/Alkaline Battery Installed

ohms

Power Module Only

Battery

J1-1 J1-2

Jl-3 Jl-4 J1-5

VSUP

CHASGND PROTECTIVE

GND

CGND

0 (REF) BAT/LINE 2.6 to 3.0 VBAT

+7.3

to 9.0

PROTECTIVE

GND

0 (REF)

3.7 to 4.3 +7.0

All values listed are in Volts DC

to 9.0

NC PROTECTIVE GND

0 (REF)

3.7 to 4.3

7.0 to 13.5

t9.0 to 16.0 PROTECTIVE

GND

0 (REF)

4.3 to 5.1

+7.5

to 13.5

1.10

POWER AND POWER LINE

POWER RATING

9 Watts power module operated while simultaneously charging battery.

0.6 Watts battery power

OPERATING MODES

Power Line (Mains) Battery- Rechargeable

(NiCad)

or Non-Rechargeable (Alkaline)

LINE (MAINS) VOLTAGE

115 V or 220 V

LINE (MAINS) VOLTAGE VARIATION

+lo%

LINE (MAINS) FREQUENCY RANGE

50-60 Hz

LINE (MAINS) FREQUENCY VARIATION

+5%

1.11

BATTERY PACK VOLTAGE

BATTERY VOLTAGE OPERATING RANGE

7.0 v to 9.0 v

BATTERY PACK TYPICAL OPERATING LIFE

NiCad: Alkaline:

22 Hours 45 Hours

1.12 ENVIRONMENTAL CONDITIONS

OPERATING TEMPERATURE RANGE

15 to 40 Degrees Celsius

SHELF TEMPERATURE RANGE

Power Module Operated:

-40 to 60 Degrees Celsius

Battery Operated: -40 to 40 Degrees Celsius

RELATIVE HUMIDITY RANGE

5% to 90%

1.13

MECHANICAL DIMENSIONS

Weight:

5.6 lbs (2.53 Kg) Weight of Battery Pack: Size:

13.25"W

14"D

1.5 lbs (0.68 Kg)

3.75"H

(33.66 cm x 35.56 cm x 9.53 cm)

1.14 MATERIALS USED IN MANUFACTURE

GSI 17 Case Assembly

GE Cycolac T Battery Option Case Assembly - GE Cycolac T Power Module Case Assembly - Noryl SE -

100J

(Flame Retardant)

1.15 LEAKAGE TEST (AC) CONNECTED/SAFETY TEST

Leakage Current High Voltage Breakdown

<25 uamps

115 V operation 220 V operation

>3000

>4000

v v

1.16 HEADBAND STATIC FORCE

1.6 to 2.0 pounds when

earcups

are 5.7 inches

apart.

Measured

with distance center of headband to center of earphones equal to

5 inches.

1.17 EARPHONE CUSHION ATTENUATION

Frequency (Hz)

125 250 500 750

1000 1500

Attenuation

6.5

4.5

7.0

10.0

15.5

18.5 2000 26.0 3000 4000 6000 8000

30.5

33.0

27.0

24.5

1.18 ACCESSORIES

Supplied Cataloq Numbers

Test Headset (TDH39) Audiogram Forms (1 pad of 50)

Instruction Manual

Battery Pack Assembly

(used with 1717-9710,

1717-9715 models only)

8000-0175 1717-9600 1717-0100 1717-2010

AC Power Cord,one of the following:

120 v (US) 220 V (Euro plug) 240 V (UK) 220 V (Generic)

8000-0240 8000-0241 8000-0242 8000-0250

GSI 17's with serial numbers below # 0856 require a different power module.

See Section 9, Power Module,

for details. Optional Catalog Numbers Response Handswitch

Patch Cord, 2 Conductor Audiocups Battery Pack Assembly

7874-0156 4202-0505 8000-0155

1717-2010 Battery Pack includes GSI supplied NiCad Battery. May also be used with six

(6),

Size C, Alkaline

Batteries (not included)

Replacement NiCad Battery

8410-0060

Figure 2-1:

CONNECTORS, CONTROLS, INDICATORS

SECTION

This

Connectors,

Figure

Controls,and Indicators.

2.1 THE FRONT PANEL CONTROLS AND INDICATORS (FIGURE 2-1)

section of

2-l for the layout and positioning of

F2 - Range

Present Bar for stimulus presentation.

Functional Description

the Service Manual is

Controls,

Power switch and indicators for ON

increase standard operation is indicated by the LCD.

HL control for setting stimulus Level indicated on LCD.

and Indicators of the GSI 17.

extension pushbutton allows

the

stimulus intensity 10

maximum

HL at

used to

any

frequency

"+"

being lit on

intensity

describe

Refer to

all

(1)

Connectors,

and OFF (0).

operator to

above

level.

the

its

the

F6 - Subject response

F7 - Frequency

F8 - Routing

F9 -

F10 -

Loudspeaker

presentation indicated by illuminated LED.

that the test button.

control for setting stimulus

Frequency indicated in window adjacent to control.

switch for routing the stimulus signal to

the

indicated by illustration of

Tone

type.

---

Low battery indicator to alert the

the available depending

are used).

left or

type

= warble tone = steady tone = pulsed tone

batteries

switch for setting

(recharge or

on whether

in operation as such.

indicator LED shows the operator

subject

right

have a

has pressed the handswitch

earphone.

limited replace

NiCad

Left or

subject.

the

alkaline

stimulus

operator

operating

batteries

Actual

frequency.

right

soon,

batteries

tone

when time

2.2 REAR PANEL CONNECTORS AND INDICATORS

R1 -

Power input position

and rear panel indication of input

jack with front panel

indication of

power

specifications.

Attention,consult accompanying documents.

Earphone output jacks with front panel

indication of left and right phone provided by illustration of subject.

Subject response switch input jack with front panel

indication of position.

Calibration switch indication.

2.3 GENERAL OPERATION OF CONTROLS

All

initialization is complete, in

depends on the HL selection. When the Extended Range is

controls

this

document and for the Extended

are

valid at

except for special cases as indicated

all

times

Range

once

the

Pushbutton

power up

which

invalid there will be no indication given to the operator other than absence of the

"+"

LCD segment.

the

All polled

state.

All operations of all controls are

controls are checked every 12

msec

for a

debounced

change in

for 12

msec

before processing. The

Extended

manner.

and

hold manner (except in the Calibration and Diagnostic modes

The Present Bar and Response Switch operate

Range pushbutton operates by a push ON,

by a

push OFF

press where the Present Bar is push ON, push OFF). When a press and hold type control is operated all other controls

are still active.

When the operation of a control is being processed the processing

all

other controls is delayed until the first

operation is

completed.

2.4 POWER UP INITIALIZATION

When

the power switch is set to the ON position

the

instrument

will go through the following initialization process:

All microprocessor

internal

and

external

hardware

components of

system will be initialized for the

the

required

type of operation.

All

LEDs

and LCD segments will be turned on to indicate that

the power up initialization is in progress.

The RAM will be tested using a read after write verification process.

initialized will be displayed on the HL display and the instrument halt.

After each location is tested its value

to 0.

If an error is detected, an

will be

error

code will

The generate a stored in the EPROM. using any of the RAM. will be displayed on the HL display and the instrument halt.

The operating mode of the instrument will be determined by

the position of the Cal/Normal Switch and the four Cal Option Dip Switches. Refer to Sections 3 for the Calibration and Diagnostic Mode initialization. remaining initialization process will be performed for the Normal Mode.

The

initialized to 0 HL.

analog hardware

selections. After

all controls active.

2.5 SLEEP MODE

EPROM will be tested by reading the complete

current

initialized to their currently selected positions.

initialization,

EPROM to

checksum which will be compared to a

This test will be performed without If an error is detected an error code

HL selection

All other controls and displays

will

be initialized

the instrument will remain idle

and

the

HL display

according to

checksum

will be

will

The

will

All

these

with

The GSI 17 has a mode which is designed to lengthen battery life. When operation Sleep only when the unit available when connected to mains (ac) power.

If a period

operated (front panel, internal,

"sleep",

Prior to entering the Sleep Mode,

indicate 3 dashes ' - - -

mode status.

7 Volt) which will disable much of the analog circuitry.

the disconnected, a STOP state which will halt its operation.

The either the Present Bar or power switch are toggled.

the

unit

Sleep

unit has been left on, under for

Mode.

thus drawing minirnal current.

enters

more than 5 minutes, the GSI 17 will

It is important to emphasize that this mode

is operating with batteries, and is not

of 5 minutes has elapsed

external) the unit will go to

the display will be updated to

to advise the operator of its

It will also disable the voltage converter

the

the channel will turn OFF and the CPU

Mode is exited, and normal

sleep

mode,

battery power,

since

all

transducers

operation

any control was

resumed,

without

enter the

exists

sleep

(+7

When

will be

will

enter

when

SECTION 3

3.1 EARPHONE CORDS

With extended use,earphone cords tend to fray internally at

junctions with

fraying associated cord is flexed.

check control (F7) to 1000 or 2000 Hz, set HL control (F3) at a comfortable audible level,

earphone cord intermittent

scratchy the conditions signifies that the cord should be replaced.

Repeat the test for the other earphone.

3.2 HUM AND RANDOM NOISE

will ultimately either decrease the signal level in

earphone or cause signals to be intermittent as

for

signal,

sound superimposed over the signal that coincides

flexing of the cord.

Routine Maintenance

both earphone and audiometer

either condition, set

press the Present Bar (F4)

next to plug at

abrupt

changes in

The presence of any of

the

both ends,

audiometer

signal

the

connectors. This

the the

frequency

and

listening

level, or a

these

flex

for

with

three

This test can be made during the check for attenuator noise. With the instrument set on 1000 Hz,

0 to 60 dB and listen for low-frequency hum (60 to 120 Hz) and

random noise (hiss or low rushing

levels. permissible.

audible.

naive subjects and affect the accuracy of the audiogram.

Schedule the audiometer for immediate service if any of these

symptoms are detected.

3.3

DISTORTION AND FREQUENCY SHIFT

This check is most easily performed by listening to the output of

the

frequencies at

dBHL for normal ears). Listen for rattling, rasping or distortion in the tones

presented. change when the Frequency Selector (F5) is moved to a new position. other,

should be replaced. In any case,the audiometer should be

immediately scheduled for maintenance.

GSI 17

Some audible random noise at levels above 60 dB is

Below 60

Any of these noises can be confused with the signal by

through

a loud,

Listen also to ascertain that signal frequencies

If distortion is heard in one earphone but not in the

the chances are high that the earphone is at fault and

however, only the signal should be

the

earphones

but not uncomfortable, level (70 to 80

move the HL control (F2) from

sound) at all attenuator

while

presenting

all 11

3.4 SPECIAL MESSAGES

The

GSI 17 is a

microprocessor-controlled performs a self check each time the instrument is turned on self check does not occur when the instrument is "awakened" sleep mode).

the front panel LCD if any error in the instrument

is detected.

Certain messages will be displayed to the

These messages are described below.

instrument

operator

operation

which

(the

from

3.4.1 CAL

When a

calibration

"CAL" will be displayed to the operator.

function at

invalid results displayed as long as the "problem" transducer and frequency selected. changing either

transducer or frequency is

error

this

can be

(i.e.

frequency with this transducer, so

right earphone at 2000

recorded.

The word

If the calibration error is an

the

frequency or

the

selected

which

Hz),

has a

the

word

The audiometer will not

that no

"CAL"

will be

are

isolated

transducer

situation,

(i.e. left

earphone or 3000 Hz) will restore normal instrument function.

As is

service technician should be contacted immediately.

make

the

case with any instrument

malfunction, a

note of the combination of transducer and

certified

Remember to

frequency which

resulted in the "CAL" message.

3.4.2 Exx

When an error code consisting of an

"E"

and a 2-digit number (xx,

= number) appears on the audiometer's display, a system error has

been detected. not will

permit the instrument to operate.

remain on

instrument will

The GSI 17 will enter a "lockout" mode which will

the

display

shut

The specific

for

several

seconds,

itself down completely.

error

then

Should an

code

the Exx

appear on the LCD,take the following steps:

Power down,

then power up again.

This error could be only a temporary failure and may never appear again. However,

should the Exx message

reappear,

proceed to

steps b. and c.

Record the numbers that appear on the display. Contact your certified service representative and give

them the specific numbers you have recorded.

4.1 QUICK

REFERENCE

CALIBRATION

--X

a. b.

Select Calibration Mode using Cal/Norm Switch. Select Frequency and Reference HL for calibration. Select Earphone Routing (L or R). Turn Tone ON using Present Bar.

NOTE:

Display will update to the ANSI proper calibration as necessary.

e. f.

Adjust Output Level to the required SPL using the HL Dial. Store data using the

LCD Segment will illuminate to indicate storage of data.

g. h

NOTE:

REPLACED,

Repeat for all frequencies. Repeat for opposite earphone.

. .

Return Cal Switch to NORM position.

If A CAL ERROR occurs or the MICROPROCESSOR HAS BEEN

the following steps should be performed:

Short

JP1

pins 1 and 2 then power-up for 2-3 seconds.

Power-down and remove jumper.

6.6).

SPL required for

subtract or add microphone

+10 dB

Range Extender Pushbutton

(See Troubleshooting, Section

corrections

(+)

Load Default Data. (See Dip Switch 4, this section). Battery low/shut down calibration.

(See Diagnostic Mode

(D3), this section).

Attenuator maximum output level calibration. Diagnostic Mode

(D4),

this section).

Proceed with Transducer Calibration.

(See

NORMAL/CAL MODE SWITCH

NORM/CAL

LR403

DIP SWITCH S2

(SQUARE PORT)

POSITION l/POSITION 4

Figure 4-2:

ACCESS TO CALIBRATION CONTROLS

R404

LINEARITY ADJUST

DISTORTION ADJUST

---t

Freq

(Hz)

Table 4-l:

125 250 500

CALIBRATION REFERENCE THRESHOLDS

750

1000

1500 2000 3000

4000

6000

8000

dB 45.0 25.5 11.5 8.0

Standard Reference Threshold Levels re: 20 TDH39-P

9-A coupler.

earphones as measured on the National Bureau of Standards

Reference ANSI

7.0 6.5

S3.6-1989,

IS0 389-1975 Standards.

9.0

uPa

10.0

for

9.5

15.5

Telephonics

4.2 CALIBRATION MODE OPERATION

The

Calibration Mode is calibration. Normal

Mode

produce

the required SPL for the selected HL.

to determine the correct

This

used to

calibration information is used

perform

attenuator

the

transducer

during

position to

The

Calibration

the

Mode consists of two modes. The Custom SPL Selection Mode allows the selection of

SPL values Calibration

for

alternate

transducers.

Mode is used to calibrate the sound

The

Transducer

pressure

customized

SPL

level

(SPL) of each stimulus for each transducer.

4.2

CAL/NORMAL SWITCH

This switch is used to select the operating mode of the instrument.

switch to the CAL position while Dip Switch position.

The Calibration Mode is entered by setting this

is in the OFF

The Calibration Mode is exited by setting this switch

to the NORMAL position.

13.0

4.2.2 CALIBRATION MODE DIP SWITCHES

(See

"Calibration Mode Dip Switch In-Depth Description" later in

this section.) These

Mode.

Dip Switches select various options of

They are read to determine the selected options when

Calibration Mode is entered.

the Calibration

the

Switch

Function

OFF (down)

(up)

Default Data

OFF

Load

Loads the default Calibration data into EEPROM when the Calibration Mode is entered.

Custom SPL Mode

GSI

Custom

Enables the selection of user specified SPL values during the transducer calibration procedure when set to the Custom position.

Not used

Diagnostic Mode

N/A

OFF

N/A

Selected

Selects the Calibration Mode when the Cal/Normal Switch

is set to the Cal position if this switch is in the OFF

position.

The status of Dip Switches #4 and #1 are read only when the Calibration Mode is entered.

Dip Switch #3 is read and a change

in its position is processed if the Calibration Mode was entered

with this switch in the ON position.

Then the switch cay be

returned to the OFF position without exiting the Calibration

Mode.

-’

4.3 CALIBRATION MODE ENTRY The Calibration Mode can be entered via the Cal/Normal Switch at

any time except during the power up initialization phase or when a stimulus is being presented.

In these cases the Cal Mode will be entered when the initialization is complete or the stimulus turned off.

The indication that the instrument is in the Calibration Mode will be the non integer value in the format of xx.x on the HL Display.

During the Calibration Mode initialization process all

controls

will be inactive. When the Calibration Mode is entered,

low battery segment will be turned off.

all LCD segments except the

If Dip Switch S4 is

set

to the ON position the process of loading the default calibration

data except default data and checksum are being loaded.

will be started and the LCD display will have all

segments

the low battery segment turned on to indicate that the

When completed,

the

display will reinitialize to all segments except the low battery

segment will be off.

id'

The EEPROM will then be tested by reading the complete EEPROM to

generate

the

flashed on

a checksum which will be compared to a checksum

EEPROM.

the HL display and the initialization

If an error is found the word

"CAL

process will

stored

will be

continue.

Dip Switch #3 will be checked to determine which CAL mode is to be initialized.

If in the OFF position the transducer SPL calibration mode is selected,and if in the ON position, the Custom SPL selection mode will be selected.

4.4 MODE INITIALIZATION

When

the

transducer

SPL Calibration

Mode is

selected the

instrument will be initialized as follows:

Tone Type = Current selection

Frequency

Current selection Channel = OFF Calibration HL = 10 dB below the nonextended HL limit

for. the current transducer and frequency Transducer SPL = Calibration HL + Current RTL +10 dB

Pad = Out Transducer Routing = Current selection HL Display =Current custom SPL level stored in EEPROM Response LED = OFF Stimulus

On LED = OFF

Low Battery Segment = Current state

"+"

Segment = OFF

4.5 EARPHONE SPL CALIBRATION MODE

This Calibration Mode is used to calibrate the SPL for each

stimulus for each transducer.

This is done by adjusting the selected transducer output SPL level to the specified value displayed on the HL display.

This SPL value is the sum of the

calibration HL level and the Reference Threshold Level (RTL) for

the current transducer and frequency. standard

RTL value or

a custom RTL

The RTL may be either the

value

depending on

the

position of Dip Switch #3 when the Calibration Mode was entered.

The transducer

SPL calibration data is

stored in

EEPROM by

transducer and stimulus.

4.5

TONE TYPE SWITCH

This switch

operates as in the Normal Mode to select

Type of the stimulus.

4.5.2 ROUTING SWITCH

This

switch

operates as

in the Normal

Mode to transducer to be calibrated. All transducers must be and they can be calibrated in any sequence.

the

select

Tone

the

calibrated

4.5.3 FREQUENCY SELECTOR

This control frequency

operates as

in the Normal

Mode to

select

to be calibrated. All frequencies must be

the

calibrated

and they can be calibrated in any sequence.

4.5.4

The operates in operated

PRESENT BAR

Present Bar controls the presentation of the

a push ON/push OFF manner.

If the Present

while the stimulus is off, the stimulus will be

stimulus.

Bar is

turned

on and remain on until the Present Bar is operated a second time. The

stimulus will actually be turned ON or OFF when the

Present

Bar is pressed.

4.5.5

HL DIAL

This control performs the dual function of selecting the HL level at which the calibration is being performed and of adjusting the output level of the transducer.

While the stimulus is off,

Calibration HL level (Cal HL). up by 5

for each clockwise step of the selector and down

by 5 dB for each counter clockwise step.

the HL selector will select the

The level will be adjusted

For each change in

the Calibration HL level the transducer output level

(attenuator position) will be recalculated using the current

calibration data stored in the EEPROM.

the calibration HL will be from the nonextended

range) maximum HL limit to 20 dB below the limit.

the selector to select levels outside of this range

invalid.

When this occurs the level will default to the

The allowable range

(+10 dB

Operation

are

limit and the HL display will be flashed.

While the stimulus is on,the HL selector (dial) will adjust

the transducer output level to allow the SPL level to be

adjusted to the required SPL level on the sound level meter. The output level will be adjusted up by 0.5 dB for each clockwise step of the selector and down by 0.5 dB for each counter clockwise step. The output level is changed according to the HL selector by directly setting the attenuator position. Operation of the HL dial to select positions outside of the instrument range will be invalid. The attenuator position will be adjusted within the limits and the displayed SPL value on the HL display will be

flashed.

4.5.6 EXTENDED RANGE PUSHBUTTON

This pushbutton is used to store the transducer SPL data

stored, Response LED will be turned on for 2 seconds. data can

into

the

not be stored successfully, the word

EEPROM.

After the calibration data is

EEPROM checksum will be updated

and

If the calibration

calibration successfully the

"CAL"

Patient

will be

flashed on the HL display and the previously displayed SPL value

+ 74 hidden pages

Welch Allyn GSI 17 User manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Warranty

Table of Contents

FOREWORD

SECTION 1

Product Specifications

1.8 TRANSDUCERS HEADSET TDH39 Earphones with 60 ohm impedance

POWER AND POWER LINE

BATTERY PACK VOLTAGE

1.12 ENVIRONMENTAL CONDITIONS

MECHANICAL DIMENSIONS

Functional Description

2.4 POWER UP INITIALIZATION

SECTION 3

DISTORTION AND FREQUENCY SHIFT

4.2 CALIBRATION MODE OPERATION

CAL/NORMAL SWITCH

4.2.2 CALIBRATION MODE DIP SWITCHES

4.3 CALIBRATION MODE ENTRY The Calibration Mode can be entered via the Cal/Normal Switch at

TONE TYPE SWITCH

PRESENT BAR

HL DIAL