Adjusting the Display
Signal Compatibility
The PA 300 processes
RsGsBs, HDTV, and component video signals.
Potentiometer Adjustments
The PA 300 achieves its superior amplification by using two independent peaking potentiometers: LF for streaking adjustment and HF for detail adjustment.
The goal in adjusting the PA 300’s Gain and Peaking potentiometers is to produce a sharp image (i.e., an image free of streaking or smearing) on the attached display.
The most accurate adjustment method for the gain uses an oscilloscope, but you can also adjust by observation. The following instructions explain how to adjust the gain with and without the use of an oscilloscope. An oscilloscope is not necessary for the peaking adjustment.
Adjusting the gain with an oscilloscope
To adjust the Gain potentiometer, do the following:
1.Remove the cable from your source and attach a VTG 300 to this cable.
2.Use the White Field test pattern for the VTG 300 setting.
3.Remove the far end of the cable from your projector and attach the oscilloscope using 75 ohm termination.
4.Use an Extron Tweeker to adjust the Gain potentiometer until you have a 0.7
5.Once the gain is successfully adjusted, replace the source and display cables.
6.See Adjusting the peaking on the following page.
Adjusting the gain without an oscilloscope
Use an Extron Tweeker to turn the Gain potentiometer until the image reaches the desired level of brightness.
Adjusting the peaking
To adjust the Peaking potentiometers, do the following:
1.Using MS Paint and a spreadsheet, create a testing image on your PC desktop that includes squares, lines, text, and gradations of color. Use the illustration below as a guide.
2.Adjust the LF (low frequency) potentiometer until the image is free of streaking. When the LF is over adjusted, the streaking is the same color as the image, as shown below.
PA 300 Peaking Amplifier • Adjusting the Display | PA 300 Peaking Amplifier • Adjusting the Display |
