Appendix 5 - Calibration Of The Instrument - Siemens SD 270 Service Manual

Appendix 5 - Calibration of the Instrument

Siemens recommend that this audiometer should be calibrated on an
annual basis. The procedure is described in the following sections. It is
assumed that the required calibration equipment, operating procedures
and staff qualified to undertake calibration of audiometric test equipment
are available to perform this operation. Refer to ISO 8253-1 for additional
guidance.
Note: Refer to Section 3 of this appendix if more than one type of
headphone is in use with the audiometer.
In order to calibrate the audiometer you will need to obtain the instrument
password. Each individual audiometer has its own unique calibration code
or "password". If necessary, please contact Siemens or your Siemens
distributor.
1. Entering Calibration Mode
Switch on the audiometer while rapidly pressing the 'LEFT' button. The
screen will then display 'Enter Password'. Enter the 4-digit calibration code
using the four 'Softkeys' located just below the screen. Press each key
until the required digit of the code is displayed on the screen.
When the correct code is shown, press the 'ON' key to confirm. If the
correct code has been entered the unit will then be in calibration mode,
signified by "(Cal)'" being displayed on the screen. If a secondary
headphone has been enabled the earphone type being calibrated is also
displayed.
If an incorrect code has been entered the unit will return to the normal
operating screen. Turn the unit off and repeat the above instructions.
2. Calibration of Different Functions and Transducers
Note that, if required, all calibration levels can be set to zero at once by
pressing the '+20dB' key while in calibration mode.
The initial screen is for pure tone air conduction calibration. Use the
'LEFT'/'RIGHT' keys to change earphone. Change the calibration level
by using the 'SIGNAL' control. Change frequency by using the 'Hz </>'
keys. There are 11 different frequencies to calibrate (125 to 8k). Left
and Right earphones should both be calibrated.
SM010-3 Siemens SD 270 Operating & Service Manual Page 49