CurtPalme.com Home Theater Forum

[joeweese]

Im totally new in CRT projectors, bought a 1270 a few weeks ago. Everything works perfect, except I have one problem:

I have 2 horizontal lines on my projection. I feed the CRT via HTPC with 1280x720p @ 50Hz. The two lines move depending on Hz. At 50Hz the two lines nearly dont move. If I look in the lenses I see the lines on every tube. In the internal test rasters the two lines dont appear.

On the two attached pics you can hardly see the lines, in reality they are quite "sharp" with a shadow behind them.

What could that be?

[prover]

On the pictures I can hardly see the lines, can you catch a sharper image?
How does your signal chain look like? It could be a problem of the
projector input card, which one do you use?

prover

[Ben851]

That to me looks like 60hz hum... are you using decent cables going from source to projector?

Thanks
Ben

[joeweese]

2 more pics, first one shows the line quite well. Now I also saw that the picture is somehow "cuttet", see 2nd pic.

I use a IFB-20 input card (9 pin DSub) connected to my HTPC via VGA cable. Cable quality is quite good. If I connect my satellite receiver via composite video I also get these lines, but much less intensive.

[AnalogRocks]

Go into your Sony's service menu and see if there's a clamp setting.

Do the lines scroll up the screen slowly?

[AnalogRocks]

Go into your Sony's service menu and see if there's a clamp setting.

Do the lines scroll up the screen slowly?

[joeweese]

Clamp setting is set to Auto, other clamp settings -> lines are still there.

Yes the lines scroll up the screen, at 50Hz they nearly stand still.

[macgyver655]

Whats your voltage over there? 110/120 or 220/240?

[Vibe]

That looks like the clamp setting to me as well. When you change the clamp setting make sure to save it right away or else it will go back to the old one. I haven't played with a Sony in a while so I don't remember which setting was best but I think it was something like H/P.

AGAIN, make sure to save right away or it goes back to the old clamp setting that gives you those lines.

[joeweese]

@macgyver655:

We have 240V here. Label on projector says 220~240V, so that must be right !?

@Vibe:

I tried all clamp settings and also saved every time, but no change.

I also tried 1920x1080i@50Hz, no change, lines are still there. They move and at 50Hz they nearly stand still.

[macgyver655]

Those hum bars are usually induced from power. A bad power supply can cause it but since its not there with internal test patterns then its not that.

Another thing that can cause it is some what of a ground loop. I asked what power you have because here, with 110/120 volt system you can sometimes isolate it by using 3 prong to 2 prong adapters. I'm not sure how you could try this on 220/240. You would also have to alleviate anything hooked to the PC that uses A/C power.

Also are you using dual monitor setup in your configuration?

Also try a different source other then PC?

Other wise possibly something in the input card. Do you have more then 1 input card to try?

[Ben851]

As I said before, ground loop (60hz hum) - which in Europe is actually caused at 50hz:

http://74.125.47.132/search?q=cache:ajFwm6NK_BkJ:www.epanorama.net/documents/groundloop/+60hz+hum+ground+loop&cd=1&hl=en&ct=clnk&gl=ca&client=firefox-a


Try switching the refresh rate on your PC to anything not a multiple of 50hz...

[macgyver655]

[macgyver655]

[Ben851]

No worries - I wrote my original response in haste, I should have been clearer in what I meant... It's obviously not the only possibility but I figured it would be a good place to start.

Thanks
Ben

[joeweese]

Im happy!

Just plugged the power cable of the projector in another socket (at the other side of the room) and the lines are gone!!!

Thanks a lot for your help !

[AnalogRocks]

[AnalogRocks]