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Discussion Starter · #1 ·
I've been searching for information on how to set the correct G2 / screen voltages on a Sony VPH-1292 projector, but the only info I've found so far is on the 125x and 127x.

Is there anybody here that can help me with a more or less detailed description on how to set the voltages or maybe point me to where I can find more information about it?


John
 

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John:

To the best of my knowledge this is handled automatically and is NOT adjustable. If someone knows differently I know they will chime in.
 

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Discussion Starter · #3 ·
Allen, thanks for your quick reply.

"Handled automatically", is that through AKB (Auto Cathode Bias)? If so, isn't there a way to set some kind of 'default' setting that AKB uses, or am I talking through my hat?


Anyone who can confirm that there is no way of manually set the G2 voltages on a VPH-1292?


John
 

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Hi,


Do you have any manuals for the 1292? A website called www.projectorspecs.com has the installation manual for the 1292. I don't really want to go through the trouble of Downloading it and opening it right now but if you look through the installation manual they may show a place for G2 to be adjusted. I haven't found a link to a service manual for that unit.


If it's like the 127x, or the 125x, it's 3 pots located near the 3 pots used for electrostatic focus. If those pots are there, that's where the adjustment takes place and therefore, there is a place to manually adjust it.


Of course you can't set about adjusting G2 and maintain you greyscale calibration. This may or may not be an issue for you.


-Brian
 

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Discussion Starter · #5 ·
Hello Brian,


I have the Installation manual but thanks for the link. The only thing the manual says is how to set Gain and Bias with the remote control.


The reason I want to be able to change the G2 voltages is because even when setting the contrast at 'MAX' I get no blooming, line distorsions or any other picture flaws. I interpret this as either the input signal or the G2 voltages are too low. Am I wrong to believe that there should be picture flaws when setting the contrast to high?


John
 

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Hey,


Your source component may not be providing strong enough of a signal to cause the projector to bloom even at 100% contrast.


I hope someone who knows the 1291 or knows where to find a service manual for one will add to this information because I haven't any experience with that particular model.


-Brian
 

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John:

I also have the 1292 and if I set the contrast to 100 I can get some blooming but it is subtle. If you look at an 480I source and put up an 80 or 100 ire test square you should be able to see the scan lines, but as you turn up the contrast these scan lines should start to get larger and close the gaps between them. This is blooming and you should back off on the contrast until the gaps( black lines between the white scan lines) are at their max width. This is the max level to set your contrast at. If you cannot see these scan lines in the high ire test window patterns at 480I then you need to go back and focus better both mechanically and magnetically.
 

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Discussion Starter · #8 ·
Allen,


I'm not able to set the resolution to 480i. I'm using a PC with Powerstrip but I don't know the correct parameters to set. Anyway, I suppose I can do the test with any resolution, progressive or interlaced, as long as I can see the scan-lines, right?

In my test I've used the DVD from Avia displaying both 80 and 100 IRE test squares in the resolution 800x600p.

The scan lines are clearly visible with all contrast settings between 'MIN' and 'MAX'. I can't see any blooming whatsoever. I have also done the test in 1024x768p with the same results.

Would these tests give different results if the source was interlaced?

I've also tried to use the 'RGB Size' on the remote control to size down the image to the smallest possible (to make the lines more dense) but I still have no trouble to see the scan lines at full contrast at 800x600p.


John
 
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