[cheez]

My sony 1272q has a severe halo or flare around bright objects. At first I thought it was an optical problem but I removed the lenses and the flare is seen right on the tube face.


Its not noticeable on dark scenes, contrast is good, but on a dark scene with a bright object, you can see the halo very clearly. On bright scenes, the contrast is horrible, the image looks flat and washed out. The halo can be seen past the raster area.


Both the green and blue tubes have this problem. The red is not bad at all. I've tried to adjust the flare and astig rings, but that has not helped. The halo is present even at minimum contrast levels.


Please see the attached photo. Any ideas on what the problem may be?

http://www.boomspeed.com/cheez/flare.jpg

 

[Chuchuf]

I wonder if the G2 is set to high?? Those are the pots just above the electrical focus pots under the cover on the right side of the unit.


Terry

 

[cheez]

I thought that it may have been the g2 settings, so I took out the multimeter and set each to 4V as the service manual intructions advice. Then I had to redo the bias. But the halos are still there..... Any other ideas on what could cause this?

 

[Kieth]

I would start measuring the power supply voltages and see if any fall off during the bright scenes. You could have a high voltage regulation problem based on your description.


Good Luck!


--Kieth

 

[Curt Palme]

I was actually gonna say the G2 is too LOW!


The AKB on these sets can cause the tube to go out of focus if the G2 isn't being pushed hard enough. I don't think it's a supply problem, you'd have all sorts of other problems if you had power supply drift. I've never seen it happen on a Sony 12XX series.


Note that some flare can always be seen on the tube face. Is the blue and green tube face and lens clean? The blue always attracts dirt. Did it do this all of a sudden, or did you just get the projector? Are you using video or RGB? Do the menus do it?


Curt

 

[Randy S]

What is the input source? Do you have the problem with no input source connected? If you still have the problem without any scaler or htpc connected, I'd disable the AKB circuitry to rule it out as a problem source.


There's a jumper on the left side (with the projector ceiling mounted) that can be used to temporarily disable AKB. Check out this link for more info.

 

[cheez]

It does it with all inputs and internal menus/patterns. I have tried with AKB disabled but no luck.


Curt, glad you don't think its a power supply problem. The projector doesnt show any other simptoms other than the halo. I've set the G2 to 4V as instructed. How would you recommend I set them?


I took out all the lenses and they were spotless. I also checked the tube faces and they are clean also. The halos can be seen on the tube face.


The projector is new to me with about 1100 hours. Tubes have no burn. The halos have been there since I've owned this projector.


Thanks!

 

[Chuchuf]

Cheeze,

Can you take the G2 adjustment for the tubes and rotate it to a point that the symptom goes away? Forget for a second the procedure to adjust using a meter.


Terry

 

[cheez]

I adjusted the G2 setting down (with akb disabled) slowly displaying an image with a bright spot.


As I turned down the G2 setting everything but the bright spot faded to black. The halo was constant around the bright spot. The halo did not fade until the bright spot was dimmed considerably.

 

[JohnRichmond]

Are you absolutely sure the tube faces are clean? They may have some sort of residue on there that you can't see until you clean it off. My blue tube is starting to get halos like that again because it needs to be cleaned again.


When I originally got my 1251 it had 1050 hours on it and the blue and green tube faces were absolutely filthy. Now that I have about 5000 hours on it I really need to clean them again.


JohnR

 

[cheez]

yeah, I wish it was just a dirty tube or lens. They are spotless. I cleaned them with lens tissue and fluid for optically coated surfaces.

 

[MrHiEnd]

Cheez,

Any progress with fixing the issue?

I have a similar problem on my Barco BG808.


Richard

 

[Tim Wilkins]

I don't know if this will help or not but check the clamp setting that should be accessible from the page menu. The horizontal (H-Shift) may need to be set. If you have the service manual it should describe how to do this.

 

[cheez]

Richard, I haven't had much progress at all. I will be try a few different things this thursday and friday night. I'll post any results.


Tim, I'll check the clamp settings. It is set to auto at the moment. I don't have the complete service manual. How would I go about checking that the H-Shift is set correctly?


Thanks!

 

[Tim Wilkins]

Below are the clamping instructions. The H-SHIFT is

what probably makes me think this is the problem.

I'm still trying to find where the H-SHIFT adj. is at.

It appears that it isn't the SHIFT button on the

control panel or at least I don't think so. It may

take a while to locate this.

Hint: always write down any settings before changing

so that you can revert back to the original settings.


Okay here is what the Service Manual states, page 102.


Clamp is used as a standard for setting the black level

of the picture correctly. The standard position of the

clamp depends on the kind of the sync signal. Normally

the CPU judges the signal and sets the clamp position

automatically.


However, the CPU may misjudge the signal because of

noise. If the luminance of the picture seems to be

incorrect (too dark, the black color is too light,

or the luminance is unstable), the clamp position

may need to be changed.


In such case, change the clamp position following

the procedure below.


1. Press the PAGE key 3 times.


2. Select the clamp position by pressing

(left, right, up, or down arrow keys).


AUTO: Automatic setting mode. Normally set to

this position.


S on G: If the black color is too light or

seems to be green, set to this position.


H/C: If the picture is too dark or the luminance

is unstable, set to this position.


H.P: If the luminance is still incorrect after

changing the clamp setting to "S on G" or

"H/C", set to this position and perform H-SHIFT

adjustment.


3. Press the MEMORY key to save the data.


If the luminance is still incorrect after

changing the clamp setting. There may be

other problems with the input signal or

connection. Check the input signal.

 

[Tim Wilkins]

I looked through the manual and I sure don't see how the H-SHIFT is changed. I emailed the person who taught the G90 service training class to see where I can find that. Sony puts out Technical Bulletins and other service information on a CD-ROM and I asked him if it was on there. I didn't subscribe to get it or the monthly updates. If it's there then I will quite possible subscribe to get the CD-ROM.

 

[cheez]

Other than the halo's I have, what are the symptoms of H-shift not properly set?

 

[Tim Wilkins]

Not sure. The service manual doesn't go into a lot of detail about it other than what is stated in the CLAMP setting instructions. In one part of the manual it describes the processing of the signal on one of the boards related to the clamping which is related to the sync process but there are no definite descriptions given as to what can be seen to fully identify it. Perhaps someone or a previous owner changed the frequency registration and now yours won't sync. Hard to say. I asked the same person that taught the G90 class to provide me with the Sony service phone number. It will be late this evening before I can check my email to see if I got a reply. From your picture the raster looks to be shifted, does it not, so that it looks like a double raster one on top of the other, especially near the bottom of the active raster? If you can look at the 2,4 poles at the very end of the CRT necks and see if there is some sealant applied to the adjustment rings. You don't mention checking the 2,4 poles. If the sealant is broken then more than likely someone has changed the factory setting. One of the things required to check and set are those when replacing the CRT. I don't have the manual in front of me but I recall one of the steps was to put up an + pattern and checking the flare of the dots inside the + and they can be outside the pattern and therefore need to be moved/adjusted so that they are within the + pattern.

 

[cheez]

I did check the astig and flare ring magnets. They did have the original seals, but I cut one of them to see if I could do better. it was at the optimum setting.


I'm about to give up on this and live with the halos.


I'm sure its not an optical problem since I saw the halo with the lens off but there are a few things that will try to expand the contrast in bright scenes.


I will blacken the lens supports, they seem to reflect a lot of light around. I also noticed that there are opening on the sides of the lense supports that spill light from one tube into the other. I'll try to come up with something to block the light without stoping airflow.

 

[Tim Wilkins]

Here is the reply I received.


* H-SHIFT means you press the "SHIFT" key on the remote control and then you

press the arrow keys "" on the remote control to move and center

the picture or raster left to right on the screen. On some projectors,

H-SHIFT may only work if there is a signal (composite usually) connected to

an input.