Hubbell 670-801-UL - Manual (Page 10)

Pub. 42004-615L2
Model 670-801-EX and 670-801-UL SmartSeries Amplifiers Page: 10 of 15
\\s_eng\gtcproddocs\standard ioms - current release\42004 instr. manuals\42004-615l2.doc
6/97
Operation
This unit amplifies page audio for broadcast over external speaker(s).
Adjustments
CAUTION
It is necessary to open the explosion-proof enclosure to make adjustments. Make adjustments only
when the conditions at your facility are such that no explosive atmospheres can be present.
This assembly includes one control that permits adjustments to be made while the assembly is mounted in
its enclosure but with the bolted cover removed. In addition there are several internal controls that are
accessible only by removing the assembly from its enclosure.
There is a user adjustment for setting the speaker amplifier gain for the SmartVolume™ feature, which
has three components: Minimum Level, Offset Level, and VLC Level. Although they typically require no
adjustments, these volume levels can be set with the User Level Adjustment control (labeled USER
ADJ). Use a small flat-blade screwdriver with an insulated shaft at least 4 inches long to make
adjustments.
To access the USER ADJ control, perform the following steps:
1. Unbolt and remove the front enclosure cover revealing the speaker amplifier.
2. Loosen (do not remove) the two screws that secure the nameplate.
3. Pivot the nameplate counterclockwise, exposing the access hole.
A guide behind the access hole helps direct the screwdriver to the USER ADJ control.
4. When you are done with the adjustment, pivot the nameplate clockwise into position, then tighten the
two screws. Re-install the bolted cover.
Minimum Level
The Minimum Level adjustment sets the minimum output of the speaker amplifier. The amplifier can be
set from minimum to full output (12 watts into 8 ohms) in 100 discrete steps, or no output. The factory
default is step 20, providing 4 watts.
To adjust the Minimum Level, perform the following steps:
1. Turn USER ADJ fully counterclockwise and wait to hear a single beep over the associated speaker.
This switches the speaker amplifier into the Minimum Level adjustment mode. If there is an audio
signal on the page line when the amplifier enters this mode, you hear it over the associated speaker.
Otherwise, you hear an amplifier-generated test tone.
2. Turn USER ADJ clockwise to the desired minimum speaker volume level.
The amplifier remains in the Minimum Level adjustment mode for as long as USER ADJ is varying.
After USER ADJ has remained stable for five seconds, the amplifier returns to its normal operating
mode.