Level Meter Bargraph "0" (Zero) Fine Adjustment; Level Meter Bargraph Peak Led Segment Adjustment - Wohler AMP2A User Manual

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.
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