Welch Allyn AudioScope, Руководство по обслуживанию

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1.3 Introduction to AudioScopes
The Welch Allyn AudioScope (audiometer) enables the practitioner to perform a
fast, painless and objective test for early hearing loss. The AudioScope3 starts
with a Practice Tone (PT) of 1,000 Hz at a dB HL dependent upon the selected
Screening dB HL.(Refer to Page 5 of Operating Instructions). After the Practice
Tone (PT), the AudioScope3 provides screening at all four speech frequencies:
1,000 Hz, 2,000 Hz, 4,000 Hz, and 500 Hz. This test can be performed at one
of three hearing levels: 20 dB, 25 dB, or 40 dB. Selection of the hearing level is
dependent on the age of the patient. Note: there is no PT with single level
AudioScopes. If a hearing problem is suspected, the patient is referred to a
specialist for diagnosis.
The AudioScope contains a 3.5-volt halogen lamp and otoscope lens for viewing
the tympanic membrane and the ear canal prior to and during hearing
screening.
There are two types of Welch Allyn AudioScopes in use today:
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The first type is the single hearing level instrument of which there are three
models. Although they are obsolete, they can still be calibrated if they are
functioning according to specifications. Service parts are not available.
AudioScope pn 23020 - 20 dB (no PT)
AudioScope pn 23000 - 25 dB (no PT)
AudioScope pn 23040 - 40 dB (no PT)
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The second type is the three hearing level (MultiLevel) AudioScope3. (Also
known as AudioScope II) There are two versions of this second type.
AudioScope3 pn 23300 - 20, 25, 40 dB (1000 Hz PT)
The
original version of the AudioScope 3 ( three hearing level) up to and
including serial number 969999 utilizes an ASIC module. This instrument is
calibrated by adjusting miniature potentiometers on the printed circuit board.
Although the main board/ASIC is being phased out at the time of this
writing, they can still be calibrated if they are functioning according to
specifications. Some parts are available. (See Repair Parts, Section 2.2)
NEW VERSION:
A new version (starting in 1996 with serial number 967000) differs from the
first AudioScope3 in that a Microcontroller is used instead of the ASIC.
Performance specifications of the new AudioScope 3 are identical to the earlier
AudioScope 3, and the part number remains the same. Since this version
utilizes a Microcontroller with digitally adjusted pots and not mechanical
potentiometers, calibration is much easier. Tool T-13765 is used to
electronically adjust the board. This advance eliminates the limitations of
mechanical potentiometers and reduces calibration time.