© 2006 Wohler Technologies Inc. ALL rights reserved
19
AMP2A
and
AMP2A-2S
User Manual P/N
821553
Rev-
B
Level Meter Bargraph "0" (Zero) Fine Adjustment
1) Removal of the Top Cover
Remove the top cover screws (2 along upper front panel, 2 per each side, 3 along upper rear panel, 1 center top). The 919030
PCBs (2 each) are vertically mounted to chassis bottom just behind the front panel mounted LED bargraph displays; one for
each bargraph.
2) Adjustment Pot Locations and Functions
Locate
P1
on the 919030 bargraph driver PCB(s) you wish to adjust. The
P1
trimpot faces upward from the PCB edge. Of the
two trim pots visible (P1 and P2) it is the
closest
to the front panel as mounted to the chassis. See the 919030 PCB layout on
page 24 for location of
P1
.
3) “0” Fine Adjustment Setup
To the the input of the bargraph you wish to adjust, connect an analog audio signal of an amplitude of approximately 1 kHz of the
amplitude desired to give a “0” indication on the bargraph.
4) Fine Adjustment of the Bargraph “0” Level
Turning the
P1
pot clockwise
increases
the
displayed
level (sensitivity) of the associated bargraph meter. For example, to set
the zero level at +7 dBu (rather than the factory default setting of +4 dBu), adjust the level Input Gain Calibration DIP switches
(see page 17) for gain closest to that desired. Feed an analog audio signal of +7 dBu amplitude (see step 3) into the input on
the rear panel, then turn the pots
counter
-clockwise as you visually monitor the associated bargraph meter on the front panel
until the desired display setting (“0”) is achieved for the increased input level. To zero the meters for a lower input level, you
would turn the pots
clockwise
to increase the displayed level for any decreased input level.
Level Meter Bargraph Peak LED Segment Adjustment
1) Removal of the Top Cover
Remove the top cover screws (2 along upper front panel, 2 per each side, 3 along upper rear panel, 1 center top). The 919030
PCBs (2 each) are vertically mounted to chassis bottom just behind the front panel mounted LED bargraph displays; one for
each bargraph.
2) Adjustment Pot Locations and Functions
Locate
P2
on the 919030 bargraph driver PCB(s) you wish to adjust. The
P2
trimpot faces upward from the PCB edge. Of the
two trim pots visible (P1 and P2) it is the
farthest
from the front panel as mounted to the chassis. See the 919030 PCB layout
on page 24 for location of
P2
.
3) Peak LED Segment Setup
To the the input of the bargraph you wish to adjust, connect an analog audio signal of an amplitude of approximately 1 kHz of the
amplitude desired to give a “Peak” indication on the bargraph (top segment).
4) Fine Adjustment of the Peak LED Segment
Turning the
P2
pot clockwise
increases
the
displayed
level (sensitivity) of the associated bargraph meter. For example, to set
the Peak LED Segment level at +10.5 dBu (rather than the factory default setting of +9.5 dBu), feed an analog audio signal of
+10.5 dBu amplitude (see step 3) into the input on the rear panel, then turn the
P2
pot
counter
-clockwise as you visually
monitor the associated bargraph meter on the front panel until the desired display setting (top segment) is achieved for the
increased input level. To "peak" the meters for a lower input level, you would turn the pots
clockwise
to increase the displayed
level for any decreased input level.
