Sony 1272 Grayscale and G2 Baseline - AVS Forum | Home Theater Discussions And Reviews
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Old 04-15-2014, 12:35 AM - Thread Starter
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Hi All,

I have a low hour second generation Sony 1272QM I am trying to calibrate for grayscale. I have tweaked the G2 pots more times than I can count but and have not succeeded in getting a satisfactory result. I think there is some step of the process I am missing.

I started by following the guide on Curt's page that shows how to set them with the use of a digital multimeter. I chose an empty input, reset the Contrast/Brightness/bias and gain to the built in factory default then proceed to tweak them down to 1.5v(07msp tubes).

At this point I would adjust the bias so that the 05ire squares disappear into the pluge pattern put everything back together and try again. The picture is watchable but washed out. Backing off the brightness is better but I loose too much shadow.

This prompted me to do some more reading on the forums. Apparently the AKB has to be disabled with a jumper before you can set the G2s as the compensation screws with the values. This makes sense.

I applied the jumper and noticed and instant dip in brightness and increase in voltage. Twisting the pots doesn't seem to have any effect with the AKB disabled. When I reenabled it after some slight adjustments the readings were massively out (as you'd expect).

My impression is that there are two methods for setting the G2 both with and without the AKB disabled. One visually with AKB jumpered and the other with a multimeter as per Curt's guide. Could one of the pros here tell me;

- Does the AKB have to be disabled to set G2.
- If no then what should I have my brightness/contast/bias/gain set at to get an accurate reading.
- If yes why did twisting the pots slightly have no effect on multimeter readings.

Apologies as I know the answer to this lies somewhere in an old post but I have as yet been unable to find the info I'm looking for.

My eternal gratitude for any assistance.
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