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Discussion Starter #1
Hi Guys,


On a SONY 1272Q


1) What's the factory default setting for Bias and Gain? (I've reset to factory settings but the picture is horrible!)


2) When setting Bias and Gain (without any G2 adjustments) the contrasts and brightness are reset to 80 and 50 respectively. I get the AVIA Grayscale pattern by pressing Test and can adjust it to my liking. No red or green push around 20 IRE for bias and clean whites for Gain. The PLUGE pattern has the diagonal white boxes visible and the two dark boxes are invisible. The white box for Gain doesn't bloom or distort and is free of any green red or blue tint.


But as soon as I go back to normal .. my desktop and the movies don't seem correct. my NORMAL contrast and brightness values (set through AVIA) are C=38 and B=46.


All I did was reset bias and gain to factory and now i think i'm in grayscale hell.. HELP!!


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Hi,


Ok, so if you can't return to you previously saved values and you didn't write them down, you are in greyscale hell. The bias and gain are the greyscale controls. To set them right you need a color analyzer.


Even with a color analyzer they will only be set right for the default 50 brightness and 80 contrast. Whenever you bring up the adjustments for them the machine locks in those settings.


If you typically run at a much lower brightness and contrast maybe the g2 setting's are off. Adjusting the G2 can mess up your greyscale but if it's messed up already then you have nothing to lose. Find a scan of the service manual and set the G2's using the multi-meter technique or the other technique (I'm sure the two yield different results.)


Oh, and the default settings for bias and gain for my machine are bias: R60, G100, B140 and all gains are 184. I understand this was the default for ealier models and the numbers changed with later runs for whatever reason.


Good Luck,


Brian
 

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Discussion Starter #4
Brian,


I never had the Grayscale setup so I'm not sure if I was running factory default or some previous setting.. what i'm sure is that I changed to factory default to initialize everything and then realized the major mistake of not having noted down the current values which seemed to work fine.


Now u're right. i AM in grayscale hell.


i'll wait a bit for some one else to post their factory defaut settings for a later 1272Q too to compare..




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Hi,


If you only reset the bias and gain to factory defaults and haven't tried a bunch of other settings for them then you may be able to backtrack. Repeat the reset proceedure and you will have and option to return to your previously saved values this should be the settings before the reset. This works, or can work. I hope this will work.



Brian
 

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Riverside,


Have you tried changing your Color Temperature Setting (9300,6500,3200,PRESET) in the PAGE menu to see if that restores White Balance? Those actually store 4 sets of BIAS/GAIN values.


When you reset the BIAS and GAIN, you actually only did it for one of the those selections. In fact, it's pretty likely your original BIAS and GAIN settings could be retrieved by going to the PRESET setting (which is not the same as resetting to Factory Default).


Or if 9300 looks pretty good, you could write down the GAIN/BIAS values under that selection, then go to 6500, put the 9300 values in, and tweak the White Balance so it is less blue(than 9300).


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Jerry


[This message has been edited by Jerry Arseneau (edited 07-19-2001).]


[This message has been edited by Jerry Arseneau (edited 07-19-2001).]
 

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Hi,


Well, I better point out that I use a 1271 not a 1272. I would assume the numbers to be the same but perhaps that's not the case.


The best DIY method for greyscale that I've found so far is using my digital camera. I start by doing the look into the tubes and adjust bias for vanishing point like you mentioned and then dial it in the best I can with avia by eye and then I get my digital camera. I take pictures of full fields 80IRE and 30IRE and load them into photoshop and the look at the content of Red Green and Blue. For perfect greys these would be the same values. Scoping around the images I get a feel for the average balance. Then if a primary is too high or low I adjust it and start over again. Actually I only did one iteration of this but I was happy with the results. I plan to continue playing with this soon. I posted my method which drew a lot of critisism so indeed you may not even want to go this route.


Another method was posted by Guy Kuo. He recommended using a solor cell to balance the light output from the three tubes. This will yield a flat tracking of whatever color is dialed in for 80IRE white. I built the solar cell device and I like this method too.


One of these days I'm just gonna break down and get or rent a color analyzer and do it right but not before replacing at least my blue tube so It will be a while.


Good Luck,


Brian



Edit: I wish someone else like Chuck or Curt or even Wm would chime in here on some values for 1272's that they arrived at after calibrations. I'm not an expert like they are and they seem to have overlooked this tread so far.



[This message has been edited by Brian Hampton (edited 07-20-2001).]
 

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Brian,


Sorry, I don't have any record of bias and gain settings for 127x series, only G90's. And these are generally different for each projector.


You are very close, it would be very easy for me to come visit with the color analyzers and set up your 1272. If you are interested let's chat.


Wm
 

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there is something that is being missed here.


With the 12XX series machines there is a "software glitch" if you are in bias/gain mode, then you press the Test button until the external video pops up, you can make your adjustments, dial it in perfectly, then hit normal and you get a push or boost on all channels. so you need to adjust, go to normal and measure... then go back and repeat.


I am not sure of any way around this issue.
 

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Riverside,


I recall the older post's about the default settings. I wrote them down and filed them. Went like this:


Bias for Early Models:


R=128

G=128

B=128


Bias for Later Models:


R=155

G=155

B=165


Gain for Early Models:


R=192

G=197

B=208


Gain for Later Models


R=140

G=197

B=185


Above was for 6500K


My current settings for my vph-1270:


Gain


R=140

G=197

B=192


Bias


R=165

G=128

B=170



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Discussion Starter #12
Brian you've underestimated my follies .. I tried several combinations after I got stuck in grayscale hell so other than factory presets.. everything else is just mucked up.


Jerry.. that's interesting.. I wonder if this will help cuz of the different color temperatures.. and i don't even know if grayscale was setup previously (it's a used projector) for those values but it's a wonderful idea.. i'd go back and check to see if the values are any different from default for those temperatures.


I read some interesting posts in the archives.. most for NEC PJ's but I got some ideas and last night I put on my dark glasses, set Contrast and Brightness to 50 and adjusted BIAS by looking into the tubes instead of the screen to bring the -5 IRE boxes to just dissolve into the background for each tube. The values I got were much lower than the defaults and also different for each tube.


The results were 'different' My Desktop now looks amazingly clear than it ever was ([email protected]) but I think my ATI players picture 0 IRE settings) is still a tad bit short of where it was in dark details.


i'm like on the edge of a great picture.. however this was done with all my gains set to the same value (128 default as i've read in the archives). Contrast at 45 works fine ( I had a lower value before) and Brightness has to go up to around 48 (used to be around 45) to satisfy AVIA tests.


I've noted down these settings in case I can't better them. I hope someone could point out the relationship between these settings if there is any and coment on my Gain values.


Thanks a lot for the help.


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Discussion Starter #13
Thanks for the responses guys.


Dizzman, Yes.. that's exactly what I observed and thanks for letting me know I wasn't going crazy..


Mark.. thanks for the values.. surprisingly my factory defaults for BIAS were just a little different R=155, G=165, B=155 and it does muck up the dark areas. The Gain however was the same so I believe I have a later model 1272Q.


Jerry.. Thanks my man.. your advice worked.. I selected PRESET and what I got was NOT factory presets so i'm inclined to believe it was my original settings.


Having dabbled with BIAS and GAIN all weekend.. i decided to go ahead and 'correct' my original settings anyway (AFTER noting them down .. heheheh).


My PRESET's were

BIAS

R = 150c>
G = 128c>
B = 180c>

GAIN

R = 167c>
G = 145c>
B = 145c>


I stepped down a little on R in both BIAS and GAIN by two. The result is pure whites! on end credits or bold white titles.. White shirts are a detergent advertisement! http://www.avsforum.com/ubb/biggrin.gif


FWIW the Contrast is 40, Brightness 42 through AVIA.


All this has screwed me up. I see 'colors' in people's clothes and am twisting in my pants dying to just somehow 'turn off' that tinge of green in someone's white shirt http://www.avsforum.com/ubb/redface.gif


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[This message has been edited by RiverSide (edited 07-23-2001).]
 

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Hi.


I'm trying to search through the forum, but I couldn't find a very good answer to my question. My question is:

How does the Gain/Bias setting affect the picture if it's dependent on G2 settings?


I've looked at the G2 adjustment FAQ ( http://www.biggerhammer.net/mediaroom/ ) and the document just tell the procedure to set G2 settings with factory preset bias and gain. My G2 controls are still sealed with the tab thingy (that says not to touch it), so I think those are still factory setting.


For what it's worth my 1272 (manufactured January 1997, which I believe will be one of the last batches since the 1272 is being phased out then and the G70 was coming out later that year) factory preset (for 6500K) is 142/136/174 (Bias) and 178/199/174 (Gain).


So, if my G2 controls are still at factory settings (since it's still sealed), wouldn't setting my gain/bias to factory presets be good enough? To change the bias, a manual method can be used (looking into tube and make the 5 IRE signal just slightly shining), but how do you change the gain manually?


Also, when I change bias, I press the bias key and contrast and brightness is set to something else (not my regular 36/42 setting). However, pressing contrast and brightness control at this point will seem to make the contrast and brightness of the -5 and 5 IRE boxes display to be that particular setting. So, we have 2 variables here where we can fiddle with each other. I can set the brightness somewhat high and tweak the bias, or I can tweak the bias and then set the brightness. Chicken and Egg problem, which one is done first?


I would really appreciate it if someone can give me an explanation on how all these controls make or break the image we see.


Thank you.


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Ciao.

Muljadi Budiman
 
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