CurtPalme.com Home Theater Forum

[Curt Palme]

The ABL line is normal. Put electrical tape on the C lens to cover it if it bothers you.

Shaking- usually means HV arcing, and usually internal to the HV splitter. Change it, and I'll bet it goes away.

[Curt Palme]

The ABL line is normal. Put electrical tape on the C lens to cover it if it bothers you.

Shaking- usually means HV arcing, and usually internal to the HV splitter. Change it, and I'll bet it goes away.

[Francisco]

Thanks Curt. I'm still curious why it doesn't appear on my test chassis. Is it tube related? or hardware some boards?
I rather have it on my test chassis and not in my watching unit.

I'll swap splitter to begin with for H shaking.

[redfox001]

Must be tube related since you swapped almost everything else? Perhaps swap a tube to be sure I am curious what makes this line too.

[ima]

Yes , ABL line is normal

[Francisco]

Ok I know it's normal but still don't know why it shows only on one projector. Did both factory reset and swapped tube to see if it's tube related which it aint.
I'm just curious why it doesn't show on one projector if they both are factory reset. And want to know what causes it. It will disturb a full raster 4:3 picture and I can't shift it out of the way. Hmmm some more testing tommorow.

[CasetheCorvetteman]

Never seen it on mine either.

[gjaky]

I am not a barco expert, but I seem to remember that the ABL line is indeed normal on those machines, however normally it should be well over the used raster, usually not even on the tubeface. Are you sure it is disturbing 4:3? It should be move together with the raster.
ABL is a thing that helps maintain constant tube emission with wearing cathodes. So it is working in conjunction with the color corrections, it also needs a certain timing as well to send the line out, and take a sample of that, this is probably done by the CPU board, so parts of the ABL circuit probably can be found on some or all video and sync related boards and on the CPU board, changing these boards will help you rule out which board has different adjustment than in the other machine.


EDIT: OK, looked at the schematics, it says the ABL is applied on the neckboards, but that is only where the signal is injected in the video path, the control signals are originated on the vertical deflection board.

[redfox001]

Indeed looking at the schematics on the vertical deflection board there is a pot that says position ABL line position.

[Francisco]

Ok I know it's probably the ABL line, but what's annoying me that it is not on my test chassis. Also the raster on my test chassis seams to be more clear at the top. The lines start more horizontal together were the first lines on my split pack unit seams to be stretched. (see pictures) some additional info I changed every board incl. splitter quad etc. tubes etc. with the test chassis and this problem stays with the split pack. The only thing I didn't exchange was the main board where all the boards slide in. Also I saw some jumpers between scan connectors in optical unit. This is something that differs from front projector.
It annoys me that I can't find were it's coming from and how to get rid of it.
I found out that it moves horizontal with phase and raster shift, but it stays at same hight, when you raster shift vertically it will be within the image.
I hope there's someone that can help to sort this issue. Most things I solved myself but this one is a pain in the ass.
Oh and Curt I changed splitter, quad and EHT but that didn't change the horizontal little moving at startup. It also stops when projector has warmed up so I'm thinking it's the old caps in my horizontal board.

Increased brightness to see the whole raster

[redfox001]

Ok this is facinating! one wild shot. The abl line position seemed determined by the 12 V line. The fans are also on 12 V. Perhaps your fans are dragingmthe 12 V line down? Very wild guess

[CasetheCorvetteman]

Mine doesnt have that line at all, anywhere on the tube face.

[redfox001]

[Francisco]

Yes both same age and hours. I will mount original fans tonight and see if it's changing anything.

[Francisco]

Okay just changed the fans to original without resistor as original, same behavior and line. It also looks as if my whole raster is disorted wrinkels left side, mid section and top.

[redfox001]

It looks like a friend of mine might be right he thinks that there might be a bad connection somewhere possible to mass. Might be a solder joint, sometimes hard to find. Since you changed every board also the convergence tray I suppose that is one of the few options left?

[Francisco]

One thing becomes more clear and that's that this chassis is causing the ABL line in top. I didn't expect that a chassis or main board can causes this. I'm thinking of trying to solder a ABL potentiometer on vertical deflection board (on my own risk off course) and try to play with it in the test environment.
@Curt found one of your old topics about this issue did you eventually work this out? https://www.curtpalme.com/forum_archived/viewtopic.php@t=20549.html

My raster seams to have some little distortions see middle middle of the raster showing some faint vertical banding bars.
When you project a movie you can't see it, also with contrast above 30% you can't see it anymore, but as I'm a perfectionist I would like to get it better.

It's hard to see but it's there

[CasetheCorvetteman]

Is that on all or just green?

[Francisco]

On all three same

[gjaky]

I wouldn't rule out the yokes as well, as you said all the related borads have been changed. The vertical deflection board sends out an "overdriven" signal to the yokes, so either the power supply haven't got enough headroom, or the yokes don't perform well at that deflection voltages.

[Francisco]

I have put a tube complete with yokes and amp in this chassis from the test unit. On test unit no line, in Split pack the line appeared. So ruled that one as well.