Frye FONIX 7000 User manual

Maintenance Manual
©2010, Frye Electronics, Inc.
All rights reserved March, 2010
FONIX®7000
Rev. 9—March 31, 2010

Contents
1. Overview...........................................................................................1
1.1 Signal Generation Overview ........................................................................1
1.1.1 Digital Basis ...................................................................................1
1.1.2 Component Amplitude Weighting Considerations ............................................2
1.1.3 Phase of the Components .....................................................................2
1.1.4 Special Distortion Measurements .............................................................3
1.2 Signal Detection Overview..........................................................................3
1.2.1 Fast Fourier Technique ........................................................................3
1.2.1.1 Windowing ............................................................................3
1.2.1.2 Aliasing ................................................................................3
1.2.1.3 Noise Reduction .......................................................................4
2. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Acoustical Outputs..................................................................................5
2.2 Telecoil Outputs ....................................................................................5
2.3 Battery Current......................................................................................5
2.4 Digital Readout of Sound Pressure Level............................................................6
2.5 Harmonic Distortion Analyzer ......................................................................6
2.6 Attack/Release......................................................................................6
2.7 Available Tests ......................................................................................6
2.8 Power ...............................................................................................7
2.9 Electronics Module .................................................................................7
2.10 Printer, Internal ....................................................................................7
2.11 Printer, External . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.12 Test Chamber ......................................................................................7
2.13 Monitor Headset...................................................................................8
2.14 Guarantee .........................................................................................8
3.0 Specification Test Procedure ..................................................................9
3.1 Source Frequency Accuracy.........................................................................9
3.2 Digital Measurement and Readout of SPL Accuracy ................................................9
3.3 Source Attenuator Accuracy ........................................................................9
3.4 Source Output Amplitude Accuracy................................................................10
3.5 Telecoil Drive Current Accuracy ....................................................................10
3.6 Battery Simulator Voltage Accuracy ................................................................11
4.0 Circuit Description .............................................................................13
4.1 CPU Board (061-0160-XX) ..........................................................................15
4.1.1 CPU Board CPU Section: ......................................................................16
4.1.1.1 CPU Clock: ............................................................................16
4.1.1.2 CPU Supervisor:.......................................................................16
4.1.1.3 CPU Chip: .............................................................................16
4.1.1.4 CPU Buss: .............................................................................16
4.1.1.5 CPLD: .................................................................................17

4.1.1.6 Flash ROM: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1.1.7 RAM: .................................................................................17
4.1.1.8 BDM Interface: ........................................................................17
4.1.1.9 Silicon Serial Number: ................................................................17
4.1.2 CPU Board VGA Display Interface:............................................................17
4.1.2.1 Display Clock: ........................................................................17
4.1.2.2 Display Controller: ...................................................................18
4.1.2.3 DRAM: ................................................................................18
4.1.2.4 CPLD: .................................................................................18
4.1.2.5 Analog Display Interface: .............................................................18
4.1.2.6 Plug and Play Interface: ..............................................................18
4.1.3 CPU Board Front Panel and PS2 Keyboard Interfaces: ........................................18
4.1.3.1 Front Panel Keyboard Interface: ......................................................18
4.1.3.2 PS2 Keyboard Interface: ..............................................................19
4.1.4 CPU Board Top Buss Interface: ...............................................................19
4.1.4.1 CPLD: .................................................................................19
4.1.4.2 8MHZ Clock: ..........................................................................19
4.1.5 CPU Board RS232 Ports: ......................................................................19
4.1.5.1 Port0: .................................................................................19
4.1.5.2 Port1: .................................................................................19
4.1.6 CPU Board Miscellaneous Circuits: ...........................................................19
4.1.6.1 I2C Buss: ..............................................................................20
4.1.6.2 EEROM: ..............................................................................20
4.1.6.3 Real Time Clock: .....................................................................20
4.1.6.4 JTAG Port: .............................................................................20
4.1.6.5 Bottom Buss Serial Interface: .........................................................20
4.1.6.6 Other Circuits: ........................................................................20
4.2 Signal Generator Board (061-1025-XX) .............................................................21
4.2.1 Counters: ....................................................................................21
4.2.2 Logic .........................................................................................21
4.2.3 RAM .........................................................................................22
4.2.4 Logic Used by the Digitizer Board ...........................................................23
4.2.5 Digital to Analog Converter ..................................................................24
4.2.6 Low Pass Filter ...............................................................................24
4.3 Digitizer Board (060-2023-XX) .....................................................................24
4.3.1 Digitizer Board Bus Interfaces & Counter Section: ............................................25
4.3.1.1 Counters and Control Logic: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.3.1.2 Logic: .................................................................................26
4.3.2 Digitizer Board Track/Hold & A/D Section: ...................................................26
4.3.2.1 Signal Switch/Sample and Hold: ......................................................26
4.3.2.2 Analog to Digital Converter: ..........................................................27
4.3.3 Digitizer Board RAM & In Port Section: .......................................................27
4.3.4 Digitizer Board Out Port & Prescaler Section:.................................................27
4.3.4.1 Preamplifier: .........................................................................27
4.3.4.2 Prescaling Amplifier: .................................................................27
4.3.5 Digitizer Board Speech & Alias Filter Section: ................................................27
4.3.5.1 Low Pass Filter: .......................................................................28
4.3.5.2 6 dB/Octave Compensation Amp: ....................................................28
4.3.6 Digitizer Board Battery Simulator Section: ...................................................28

4.3.6.1 Battery Current Measurement: .......................................................28
4.4 Digitizer Connector Board (061-0165-XX) ..........................................................28
4.5 Printer Controller Board (061-0161-XX).............................................................29
4.5.1 Printer Mechanism: ..........................................................................29
4.5.2 CPU Section: .................................................................................29
4.5.2.1 CPU Clock: ...........................................................................29
4.5.2.2 CPU Supervisor: ......................................................................30
4.5.2.3 Microcontroller: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.5.2.4 CPU Buss: .............................................................................30
4.5.2.5 SRAM: ................................................................................30
4.5.2.6 Internal Flash ROM: ..................................................................30
4.5.2.7 External Flash ROM: ..................................................................31
4.5.3 Top Buss Interface Section: ..................................................................31
4.5.4 Internal Printer Interface Section: ...........................................................31
4.5.4.1 Head Interface: .......................................................................31
4.5.4.2 Stepper Motor Drive: .................................................................31
4.5.4.3 Printer Sensor Interface: .............................................................32
4.5.5 External Printer Interface Section: ...........................................................32
4.5.6 Miscellaneous Section:.......................................................................32
4.5.6.1 Beeper: ...............................................................................32
4.5.6.2 JTAG Interface: .......................................................................32
4.5.6.3 RS232 Interface: ......................................................................32
4.5.6.4: Power Supplies: .....................................................................32
4.6 Power Supply Board (061-0162-XX) ................................................................33
4.6.1 Power Supply Regulator Section:.............................................................33
4.6.1.1 Source Attenuator Circuit Power: .....................................................33
4.6.1.2 CPU and Printer Controller Board Power: .............................................33
4.6.1.3 Signal, Digitizer and Probe Interface Board Power: ...................................33
4.6.1.4 Power LED: ...........................................................................33
4.6.2 Power Supply Attenuator and Speaker Drive Section:........................................33
4.6.2.1 Shift Register: ........................................................................34
4.6.2.2 Source Attenuator: ...................................................................34
4.6.2.3 Speaker/Earphone Amplifier: ........................................................34
4.6.3 Power Supply Speaker Selection Section:....................................................34
4.6.3.1 Speaker Relays: ......................................................................34
4.6.3.2 Battery Simulator: ....................................................................34
4.7 Keyboard (061-0166-XX) ...........................................................................34
4.8 7020 Sound Chamber ..............................................................................35
4.8.1 Battery Simulator Board (061-0167-XX): ......................................................35
4.8.2 Sound Chamber Board (061-0084-XX):.......................................................36
4.9 7000 Probe Option ................................................................................36
4.9.1 Probe Interface Board (061-1089-XX).........................................................37
4.9.1.1 Probe Interface Board Connectors:....................................................37
4.9.1.2 Interface Board CPU Addresses: ......................................................38
4.9.2 Probe Keyboard (061-0163-XX) ..............................................................39
4.9.3 Probe Connector Board (061-0164-XX) .......................................................40
4.9.4 Preamp Board (061-0088-XX) ................................................................41
4.9.4.1 Ref Mic Preamp: ......................................................................41

4.9.4.2 Probe Preamp: ........................................................................41
4.9.4.3 Mic Power: ...........................................................................41
4.9.4.4 Multiplexer: ..........................................................................41
4.9.4.5 Mecca: ...............................................................................41
4.9.4.6 Line Driver: ...........................................................................41
4.9.4.7 Power Supplies: ......................................................................42
4.9.4.8 Headphone Amplifier: ...............................................................42
4.9.4.9 Microphones: ........................................................................42
4.9.5 EQ Board.....................................................................................42
5. Calibration .......................................................................................43
5.1 Microphones.......................................................................................43
6. Service and Repair ..............................................................................47
6.1 Fuse Replacement .................................................................................47
6.1.1 Line Fuse Replacement.......................................................................47
6.1.2 Power Supply Board Fuse Replacement ......................................................47
6.2 Electronics Module ................................................................................47
6.2.1 Removal and Replacement of the Wraparound ..............................................47
6.2.2 Removal and Replacement of Circuit Boards.................................................48
6.2.2.1 Removal and Installation of Plug-in variety: ..........................................48
6.2.2.2 Removal and Installation of Plug-in variety with rear connector plate: ...............48
6.2.3 Replacement of Bezel ........................................................................49
6.2.4 Replacement of Keyboard....................................................................49
6.2.4.1 Removal of Keyboard with removing bezel. ..........................................49
6.2.4.2 Removal of Keyboard without removing bezel. ......................................49
6.2.5 Replacement of Switched Power Entry Module ..............................................50
6.2.6 Replacement of Printer.......................................................................50
6.2.7 Replacement of Switching Power Supply.....................................................50
7. Maintenance .....................................................................................53
8 Safety Information ..............................................................................55
8.1 Rear Panel Safety Markings ........................................................................55
8.2 Safety Classification for IEC 60601-1 ...............................................................56
8.3 Connection of peripheral equipment to the 7000..................................................56
8.4 Electromagnetic compatibility .....................................................................56
8.5 Disposal of the 7000 and accessories ..............................................................57
9. Electromagnetic Compatibility ................................................................59
10. Schematics ......................................................................................65

1
1. Overview
The 7000, in composite mode of operation, produces a complete set of tones from
200 to 8000 Hz simultaneously, and is able to analyze the response of the hearing
aid to this complex signal, and displays 79 components from 200 to 8000Hz simul-
taneously on a graphical display. The 7000 can also operate in Sine Frequency, Sine
Sweep Frequency and Average Option Frequency analysis mode. The frequencies
used are from 200 to 8000 Hz in 100 Hz increments. Average Option Frequency
(sine mode only) has users choice among 6 sets of 3 frequencies.
The composite technique has the immediate advantage that the response curve
for the hearing aid can be viewed in “real time”, and for the first time the effects
of altering the setting of a control can be viewed while it is being done. Another
advantage of this technique is the capability of measuring the “real” response of an
AGC hearing aid, instead of the artificially flattened one obtained with pure tone
testing.
Analysis of the hearing aid output is done by first taking 256 samples of the signal.
These samples are taken in exact synchronism with the signal generator.
These 256 samples are then passed through a mathematical process called the Fast
Fourier Transform, which takes the timed samples and converts them into 128 fre-
quency components. 79 of these components are then displayed on the CRT screen
in the form of a graph.
A hard copy of the screen image is available through the use of the built-in thermal
printer or external printer
1.1 Signal Generation Overview
1.1.1 Digital Basis
The complex signal is generated by reading 256 12-bit data words in RAM sequen-
tially and doing it over and over again. The program is able to adjust the individual
amplitude of each signal component in the series so that it provides a correct
amplitude of drive at the test point in the chamber for each test frequency. The test
microphone is placed at the reference point in the chamber. Pushing the LEVEL
button starts the amplitude correction process. A composite analysis of the chamber
is done and correction factors are calculated which alter all of the individual drive
components so that the chamber response is flat and at the desired amplitude at
this reference point.
Chapter 1: Overview

2 FONIX 7000 Maintenance Manual
One way to think of the test waveform is to picture one sine wave of 100 Hz being
built using 256 points or steps through the sequential reading of a 12-bit digital
RAM. If we wanted to create a signal with two equal value components, we would
arithmetically add to this wave a second sinewave, say of 400 Hz. Each cycle of the
400 Hz wave would take exactly one fourth as many steps as the 100 Hz wave to
produce, or 64 steps. When these two sets of steps are added together we would get
a composite wave with two frequency components.
1.1.2 Component Amplitude Weighting Considerations
The amplitude of each frequency may also be dependent upon its placement in the
frequency spectrum. If a white noise equivalent is to be used, then every multiple
of 100 Hz will be used and will have equal value amplitude. If a speech spectrum
is to be approximated, the amplitudes of the components in the spectrum will drop
at a rate of 6 dB per octave above 900 Hz when viewed on a standard heterodyne
or Fast Fourier analyzer. This sloped correction is produced by using analog filters,
since we would very quickly run out of digital resolution while covering the 3
octaves between 900 and 7200 Hz. 18 dB equals a ratio of about 8 to 1.
After the signal is received from the hearing aid and passed through the preamplifi-
er, it is run through a high frequency emphasis amplifier to restore the 6 dB/octave
loss so that we can get a compensated gain response picture.
The RMS amplitude of the drive signal increases in proportion to the square root of
the sum of the squares of all of its components. Thus, if a particular RMS value of
drive signal is needed, both the number and the individual amplitudes of all of the
components must be taken into account. A multiple frequency signal will then have
smaller component amplitudes to produce the same RMS drive to the device under
test as that of a sine wave signal drive which has only one frequency component.
1.1.3 Phase of the Components
Another interesting problem encountered is that the individual components of the
wave cannot be allowed to line up in phase, or the composite signal will consist of
a series of spikes with very little in between, or an impulse drive. The disadvantage
with this type of drive is that it makes very heavy demands on the dynamic range
of the hearing aid under test. Hearing aids are not known for their large dynamic
ranges, so this type of waveform must be avoided. To produce a moderate crest fac-
tor noise equivalent, it is necessary to skew the phases of all of the components so
that a given RMS amplitude of signal has a low peak value. A computer program
was used to determine the optimum set of phase values.

3
1.1.4 Special Distortion Measurements
Harmonic distortion tests can be run by generating a signal consisting of only one
sine component at a time, and using the Fast Fourier analysis program to determine
the spectral distribution of harmonics.
Intermodulation tests are automatically run using the composite waveform. If pres-
ent, this type of distortion is immediately apparent when viewing the gain or power
response of the hearing aid.
1.2 Signal Detection Overview
1.2.1 Fast Fourier Technique
The assumed technique for making response measurements is the Fast Fourier
Transform. This technique is ideally suited to a system that is used to analyze a
digitally generated waveform, since the sampling process can be locked to the sig-
nal generation process, thus eliminating one of the main problems with the FFT,
the windowing of the measured waveform. A rectangular window is thus possible
and used. That is, all sampled components are used as measured.
1.2.1.1 Windowing
The FFT requires that the signal being sampled is exactly repetitive in order
to achieve a clean spectral display. If there is an abrupt discontinuity between
the first and last samples taken, the transform can only assume that large high
frequency components are present in order to generate the discontinuity. Use
of the internally generated signal helps to eliminate this problem; if a random
noise is present in the signal being measured, it will appear in the response
display.
When the sound drive is switched to “OFF” the 7000 is turned into a general
purpose spectrum analyzer and can be used for analysis of signals. When this
is done, mathematical windowing is used as is done with standard FFT analyz-
ers. This windowing is done by multiplying the first and last samples taken
by a value close to zero. The next two samples in from the ends are multiplied
by a larger quantity. In the center of the group of samples, the values are mul-
tiplied by a compensating factor greater than unity. The windowing function
used is called a Hanning function.
1.2.1.2 Aliasing
A further requirement is that the bandwidth of the measured signal be con-
trolled so that its frequency does not exceed a value of 1/2 the sampling rate.
Chapter 1: Overview

4 FONIX 7000 Maintenance Manual
The usual way to do this is with a multiple stage “brick wall filter”. A conser-
vative design will not use a bandwidth equivalent to the limit stated above. It
will instead stop the analysis well before the limit is reached. In the present
system, therefore, the upper frequency limit is set at 8000 Hz, even though the
theoretical limit is 12800 Hz.
Aliasing shows up as a generation of random or non-random dot patterns in
the sampled data points, and occurs when the signal can take a number of
excursions between samples. This aliasing in an FFT will produce a number
of components in the low frequency portion of the spectrum that are really not
there. It is also desirable to eliminate the high frequency components from the
signal generator portion of the system. A brick wall filter is used there also.
1.2.1.3 Noise Reduction
The effects of ambient or hearing aid noise can be reduced by the use of signal
averaging because the sampling process is exactly synchronized with the sig-
nal generator.
Noise reduction averaging is done in steps of 2, 4, 8, and 16. The process is
done by use of an averaging buffer. The data is added to the data already in the
buffer used to create the last spectral display in a ratio of 1/2, 1/4, etc., depend-
ing on the averaging called for. The result of the addition is then divided to
get a properly scaled number. The effect of the non-synchronous noise is thus
reduced because of the averaging process.
Averaging does not slow down the display process, but does slow down
the effect that an acoustical change will cause on the displayed waveform.
Changes in the phase of signals will also show up if averaging is being used.
The change of phase is accomplished by movement of the hearing aid in a
sound field while the measurement is in process. The effect of phase changes
is a dropout of the signal and an eventual recovery to the correct level when
the motion has ceased.