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Sony G90 C-Element Change

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For definitions of air coupling (AC),  liquid coupling (LC), or c-element, see this page.

The Sony G90 liquid coupled (LC) projector comes equipped with a tinted green c-element that, while tinted green, isn't tinted quite enough for accurate SMPTE "C" or "HD" green primary colours.  The result is slightly yellowish greens.  Other projectors such as the Electrohome Marquee line use correctly tinted green c-elements.  A lot of liquid coupled projectors do not come with tinted c-elements at all.

Less tinted (or completely untinted) c-elements are usually used by manufacturers to boost light output.  Changing from untinted c-elements to correctly tinted ones will reduce light output by approximately 10-20%.  Most home theater enthusiasts will agree that this is a small price to pay for correct colours.

Sony G90 stock green C-Element on the left, Marquee C-Element on the right

Below are the correct and measured primaries for both types of tinted c-elements taken with a PR-650 SpectraScan Colorimeter:

  • Correct SMPTE "C" green primary values:  x=.310 y=.595
  • Correct SMPTE HD green primary values:  x=.300 y=.600
  • Measured G90 (with stock c-element) primary values:  x=.330  y=.587
  • Measured G90 (with Marquee c-element) primary values:  x=.311  y=.603

    (Measurements provided by Ken Whitcomb of Calibrations Inc.)

As you can see, the stock filtering is not quite as close to the true SMPTE "C" or "HD" values as the Marquee green C-Element.  The solution for G90 owners is to simply replace their existing C-Element with a Marquee c-element!

For an in-depth comparison and analysis of the Sony and Marquee C-Elements see this report produced by Craig Rounds of CIR-Engineering Precision Theater Calibration.

The following procedure and pictures were provided by forum member JohnHWman. Thanks John! 

Here we are with a new G90 step by step procedure: The Sony stock green C element replacement with a Marquee 9" 'G' one to improve the color purity of the G90.  I have made this change to both of my G90 projectors.

Thanks to Tim Martin of for providing me the two Marquee C-Elements ;)

Please note that Terry (Chuchuf) help me with some explanation on the critical part of this job (carefully remove the rubber bellows from the Marque recovered Green C-Element). So thanks to him as well !

Here are the steps!

1. Unscrew the four mounting screws from the LC housing:

2. Open the G90 top cover and unscrew the four Green CG block fixation screws from the chassis:

3. Twist the CG 180 on the back of the unit. Remove the white and red flat striped wires from C board  then disconnect the C board from green tube pins:

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