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Model 780/785-001 and 7805/7855-001 Explosion-proof Handset Stations
Pub. 42004-156D
d:\standard ioms - current release\42004 instr. manuals\42004-156d.doc
03/04
Maintenance
The following adjustments are accessible through the rear amplifier chassis using a small screwdriver. The
handset/speaker amplifier section must be completely removed from the enclosure to access these controls.
A silk-screen on the rear of the amplifier identifies the following controls.
•
Microphone Gain
: adjusts the gain level from the microphone signal to the page or party lines.
•
Receiver Sidetone
: adjusts the amount of signal transmitted from the microphone to the receiver. To
properly adjust the sidetone, blow into the handset microphone while turning the sidetone adjustment.
The sidetone is correctly set when the person blowing into the handset can barely hear themselves.
•
Receiver Volume
: adjusts the gain level from the party line to the receiver.
•
Speaker Volume
: adjusts the volume level of the speaker (if any) associated with this station.
Troubleshooting
The following table lists some hints to aid technicians in troubleshooting.
Problem
Solution
Outgoing conversation level
requires adjustment.
Adjust the microphone gain at the amplifier.
Incoming conversation level
requires adjustment.
Adjust the receiver volume control at the amplifier.
Sidetone (how the operator
hears himself) requires
adjustment.
1.
Adjust the receiver sidetone at the amplifier.
2.
Check that the system cable connections to the resistors in the line
balance assembly are properly terminated.
Feedback occurs only during
page.
Ensure the muting feature is enabled. See the Mutual Muting section of
this manual for details.
Crosstalk occurs.
One or more system cable pairs may be improperly terminated. Visually
inspect the system cable connections for accidental crossing of the cable
pairs or grounds.