5.2 Meter Alignment
Under no circumstances use the meter mechanical
adjustments on the meter front to correct readings.
The electronically ‘zero biased’ meter settings will require
periodic re-adjustment. The metering circuit is necessarily very
sensitive, change from the ‘zero’ position is quite normal and
is not a cause for concern. The causes are normally slight
changes in valve performance due to ageing or variations in
the mains supply voltage.
5.3 Meter Adjustment
Procedure:
1. Turn power on, wait for five minutes for the unit to warm up.
2. While waiting, make tea or other refreshing beverage.
3. With no signals present at the input, ensure Input Level
controls are turned right down.
4. Set Threshold to ‘zero’, Attack to ‘Fast’, Release to ‘Slow’.
5. Ensure Stereo Link switch is in ‘up’ position (no linking).
6. Use a trimming tool or small instrument screwdriver turn the
appropriate multiturn preset located on the front panel below
the Power and Stereo Link switches until the meter needle
is at the ‘0’ position on the scale.
7. Repeat procedure to other channel.
8. Drink tea or other beverage.
5.4 Distortion Trim
Always get this done if a signal valve has been changed.
This procedure should be carried out by qualified personnel only.
Test Equipment required:
Low distortion Audio signal generator.
Distortion Analyzer or Meter Trimming tool.
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