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Discussion Starter · #1 ·
I've recently replaced my sony 1272 with a G70. I have 2 questions for those folks more knowledgeable than myself. Using a Sencore CP-288 color analyzer I have been unable to get a flat grey scale. My firmware is new, I believe v1.10. In older model g70's apparently pushing both the bias and gain keys together gets you into some sort of gamma correction menu or tells you if you have gamma correction. This version of the firmware does not. Is there any way to get a flatter grey scale on this Sony model?

My second question concerns the jumper positions on the B input board. All my video except for HDTV is processed by a Faroudja VP400 line quad. The ouput from this unit apparently requires 75 ohm termination at the display device. If I put jumpers CN35, 36, 37 in position 3 or terminated, the picture is dark and frankly looks better without the terminating jumpers in position 3. With the jumpers in postion 1, or not terminated, I do have to turn the contrast to 50 and brightness to 20 to avoid blooming, with the jumpers on position 3 the contrast is set to 80 and brightness set to 50 but the picture seems too dark. What setting should be used? What are the jumpers CN38, CN39, CN40 for?

Lastly (did I say two questions), I have patchy yellow spots which I can see on an all white screen. I can get rid of some of this using MG Defocus of blue but then my focus spot size for blue gets bigger and less focused. Any ideas?


Thanks.
 

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How flat is your greyscale right now?

It's really a matter of what you consider "flat".

Most CRT's don't really calibrate perfecting flat, if I get my XG within +/- 350 degrees I consider that well calibrated, and as flat as it's going to get. My Ampro 3600 was within that same range. The Marquee 8500 was the flatest calibration I've been able to do...it was within +/- 200 degrees. That's projecting 12 fL at the screen.

The blue gun has a temp peak at around 60-70 ire, and it falls off quicker at the top and bottom of the scale as well. I believe there are two other contributing factors to a flat greyscale, first is defocusing of blue, and second is how hard the tubes are being driven (blue especially) the higher the contrast, the bigger the blue peak.

You would think the engineers would have created a blue neck board that took this into account, and it's amplification curve would be the reverse of the blue tube's light output curve.
 

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With respect to the termination, have you got AKB on or off? If it is off the picture will be far too dark, and this also makes it difficult to get a flat greyscale.
 

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Discussion Starter · #4 ·
ABG is set to on, if I set it to off the picture is entirely too dark.

I'm going to follow the service manual color balance procedure and see if I can get a flatter response.

Regarding the B board jumpers CN35, 36, 37 terminate R,G,B to 75 ohms. CN38, 39 terminate H and V sync. CN40 I can't figure out. The service manual schematic has the jumper labeled as HS FIX, HS NORM, HS SEP. Position 3/2 is HS FIX, position 2/1 is HS SEP, which setting do you use and what is this jumper for?
 

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If you are using yr DVD player to provide the picture that you are judging as too dark it may not be the projector at all !!!


While I was fiddling with mine Sont I was upset by a dark picture. couldnt seem to fix it.


I displayed a pluge pattern from my DVD test disk, and with the brightness on the scaler and tyhe projctor set for normal I couldnt see any of the dark pattern. The -5ire and the +5ire patterns where not visible at all.


I raised the brightness on the projector as well as the scaler and still couldnt see them. They where crushed under black.


Rein of fire was unwatchable with all the detail under black.


I had a look at the DVD player and found that the dfault brightness level was totally wrong. That meant that almost all shadow detail was crushed out. making the picture so dark it was horrible.


I raised the brightness by about 15% so the pluge was visable reset the brightness on the PJ and the scaler and was blown away.


All fixed !!!!!


Check your DVD players brightness setting.


I have to reset it everytime I turn it on now but at least its right and the picture is lovely.


Graham
 
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