Inter-m SC-9216R Operation Manual page 11

less than 100ms. Because the test volume is relatively low, and the duration so short, the test is very subtle
(generally inaudible) and may be performed while the system is in use.
Reference values are established by depressing the Op Mode button several times until the desired "Save"
options are displayed, then depressing the ENTER button. These options include menus that allow ALL channels
to be changed at once or a SINGLE channel to be changed individually without affecting the settings of other
channels. The act of establishing a Reference value deletes the previously stored Reference as does activating the
Memory Clear function. Options include a choice between W or Z and 70V or 100V. One must be selected but
the selection may be done arbitrarily in most applications. The Z selection was primarily provided to facilitate
possible future product upgrade capabilities. The 70V and 100V selections allow displayed impedance values to
be compared with system documentation or used in creating "as builts". A wide deviation may occur in such
comparisons and is generally not cause for concern. Either the 70V or 100V selection may be used with 25V or
140V systems but the impedance displayed will deviate significantly from published system component
documentation. Test reliability will not be affected.
Be sure to only store reference values when the speaker channel or system is properly configured. If for example,
an "open circuit" is stored as the reference, then the test will not identify an open circuit as a problem.
Speaker Attenuators.
Use of speaker attenuators (or volume controls) in a speaker line will result in a change in impedance with
changes in attenuation settings. This impedance change may result in a Fault indication on the SC-9216R and
the SC-9116R (expander). The following actions are recommended when a speaker attenuator is on the line.
These instructions apply to channels in which changes to an attenuator is permitted and should not result in a
Fault indicator.
1. Verify that the speaker channel is operating normally.
2. Adjust the attenuator to the minimum attenuation position.
3. Save the current condition of this channel as the Reference value. Single channels may be saved without
saving all channels at once.
4. Switch the channel check switch to the OFF position for this channel only. This switch will be found on the
rear of the SC-9216R/SC-9116R.
5. Return the attenuator to the desired operating position and continue with normal operation.
6. This channel will not be checked while the switch remains in the OFF position.
7. The channel may be checked by adjusting the attenuator to the minimum attenuation position and switching
ON the channel check selector.
These instructions apply to channels in which changes to an attenuator is not permitted and should result in a
Fault indicator.
1. Verify that the speaker channel is operating normally.
2. Adjust the attenuator to the desired position for normal operation.
3. Save the current condition of this channel as the Reference value. Single channels may be saved without
saving all channels at once.
4. Subsequent changes to the attenuator will indicate a Fault. It is possible that opposing changes to two or more
attenuators could net the same impedance as the reference impedance and the changes not be detected. See
Fault Criteria.
SPEAKER LINE CHECKER
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SC-9216R