Barco 801s horizontal linearity adjust

So my cables are routed through the ceiling now and the installation is very neat. PJ is square, picture is awesome... Just a slight issue with horizontal linearity. It's not really noticeable except if I put a test pattern up, but is there a pot or something to adjust the overall horizontal linearity, or do you have to play with the h-size and h-pos pots for each tube?

It's something I noticed on the testpattern with the tubes off, so it's not an install error.

[Mad Mr H]

I need to make sure you do mean linearity

there are the width coils tha I think need to be set first.
then h position, then size.

the linearity will always be OFF and should be corrected in the convergence.

I asked this about a BG1208s/E as I thought there was something wrong, as the red and blue tube are offset to the green this will happen and the smaller the screen the more obvious this gets.

If you mean the GREEN has issues then I would look at the H board for a damaged h lin coil maybe.....

is your a Data or Graphics?

I have sold ONE of my 801s pair and have ONE left, still on the ceiling but it must make way for my new PJ.....

I have the graphics update kit for one pj, and possibly enough to do a second.....I was going to do that to mine but never got round to it......increases the resolution available....and adds scheimflug adjustment....and less drift......and a bit smile on my face! and will get the best from your 801s.

If you already have a graphics then well done very rare as they were £5K extra when new....

Sort of not too bothered about increasing res (at least for now, I've got nothing to drive it higher) - and the shiempflug adjustment... well nothing that well placed washers can't do!

By Linearity, I mean that when I put a test grid is up, the distance between squares on the left is slightly smaller than those on the right.

I've done the coils, the size and position following curt's website and have them spot on. It's not an issue with the green tube, it's the same across all three.

I'm just curious to know if there is an adjust like on the selecos for horizontal linearity like there's an adjust in the menu for vertical linearity.

[kalW]

Pot P1 and coil T1 on the horizontal deflection board are used to adjust horizontal linearity. They're supposed to be done at 15Khz, but can be done at higher freq's as well. Just make sure to adjust and then check other freq's that you may use to make sure things are ok.

I recently received a basically brand new Zenith 1200 (aka Barco Cine 8 Onyx) and the P1 pot was completely cranked to one side such that the grids on the left side of the screen were smaller then on the right side. (The left side image had a slight in/out wobble like a curtain as well). Turning this pot in the other direction and measuring with a ruler fixed all this.

I was told that the techs that had the unit before me had no idea what they were doing. Sheesh.

Kal

wicked! thanks kal. i'll investigate over the weekend!

[kalW]

No problems! See this thread over at AVS for more info:

http://www.avsforum.com/avs-vb/showthread.php?t=598986

Kal

[cosaw]

I've done the coils, the size and position following curt's website and have them spot on. It's not an issue with the green tube, it's the same across all three.

Lex are you refering to deflection coils rotation? When you say position are you talking about left right up down or do you purely mean rotation?

Also what safety precautions did you use? Rubber gloves and shoes etc? Are you gonna attempt the astigmatism next?

I seem to remember at least one of P1 and/or T1 are extremely difficult to adjust without the use of an extender board. Also I think T1 is some sort of coil with inductive properties or something and if you use a steel scredriver it can get extremely hot and melt - therefore make sure its a plastic screwdriver! My memory is hazy on this and can't get to my pj at the mo but worthwhile checking up.

By the way there is a master width pot on the smps but obviously this does nothing for linearity.

Kal with the 15k are you just refering to the horizontal scan? Is there a standad 15k rate resolution/test pattern in the barco software?

Knowing me I'm also gonna wana get everything spot on so its nice to get everyones thoughts!

[kalW]

Originally Posted by cosaw

I seem to remember at least one of P1 and/or T1 are extremely difficult to adjust without the use of an extender board.

That would be T1. P1 is a pot that's easily accessible when the projector's running.

I asked about the interaction of these two controls in my AVSforum thread but never got an answer. Every service manual I've looked at mentions to adjust P1 with an 18Khz signal, and adjust T1 with a 15.6Khz signal. They even say that if 18Khz is not available, to "use something close".

Since I don't have extender boards (not that hard to make though), I only adjusted P1 on mine.

Also I think T1 is some sort of coil with inductive properties or something and if you use a steel scredriver it can get extremely hot and melt - therefore make sure its a plastic screwdriver! My memory is hazy on this and can't get to my pj at the mo but worthwhile checking up.

I would skip adjusting T1 at all... stick to P1. (Unless someone tells me why).

Kal with the 15k are you just refering to the horizontal scan? Is there a standad 15k rate resolution/test pattern in the barco software?

Yes and yes.

Kal

Originally Posted by cosaw

Lex are you refering to deflection coils rotation? When you say position are you talking about left right up down or do you purely mean rotation?

Sorry that is confusing isn't it. By coils, I meant the horizontal width coils with a plastic tweaking tool. I may well have a pop at the deflection coils this weekend as I think the green is a touch off.

Originally Posted by cosaw

Also what safety precautions did you use? Rubber gloves and shoes etc? Are you gonna attempt the astigmatism next?

Safety... Hmmm... There's an idea!
Previous pjs I've done deflection on have been a bit easier access (probably why I haven't gone into it yet) and I haven't needed to get close to anything dangerous. I'll take both those ideas on board though... Good suggestions.

I'm happy with the astig at the mo, so I think I'll save that for tweaking next year!

Originally Posted by cosaw

I seem to remember at least one of P1 and/or T1 are extremely difficult to adjust without the use of an extender board. Also I think T1 is some sort of coil with inductive properties or something and if you use a steel scredriver it can get extremely hot and melt - therefore make sure its a plastic screwdriver! My memory is hazy on this and can't get to my pj at the mo but worthwhile checking up.

My new plastic 'tweakers tool set' from maplins seems to be quite good, but it doesn't have a really proper flat head unfortunately.

Originally Posted by cosaw

By the way there is a master width pot on the smps but obviously this does nothing for linearity.

Kal with the 15k are you just refering to the horizontal scan? Is there a standad 15k rate resolution/test pattern in the barco software?

Knowing me I'm also gonna wana get everything spot on so its nice to get everyones thoughts!

15k is a straight video frequency is it not, so you can put that up from the internal grid or hook up the dvd vis composite or s-video.

Thanks for all this.... Results to follow sometime Sunday morning I guess!

....edit.... ok Kal's answered the last bit quicker than I could type all this!

[cosaw]

Yes just checked a service manual Kal your right about it being T1. Perhaps T1 is like a master adjustment and P1 is a Fine adjustment. Therefore T1 would probably be as close to correct as pos from new being adjusted correctly and the trimpot would then just be for fine tunining. This is pure speculation as I don't know either way.

Its worth noting also that it seems that its not always labeled as P1 so we shouldn't generalise. If anyone is gonna fiddle its worth making sure whether were all talking about Data or Graphics grade machines I suppose as well. Also check board numbers and make sure you get the exact service manual module if you can. I say all this cos I have a data with a 7617415 horizontal board which is a newer version of the 761741 which I also have as a spare. I also have pdf files for both. It seems 5s and 7s were added to the serial numbers when board revisions were done.

So whats my point? 7617415 has linearity coil at 15Khz and P1 at 18Khz but there is no higher adjustment. However, never mind the confusion over two places to adjust as the older 761741 board has three places! A linearity coil (T-whatever) and P2 for 22Khz and P1 for 50Khz. Notice here that P2 is lower than P1 - no I haven't got it back to front! ??? More confusion! All I'm saying is make sure you know what board you've got and what manual is relevant. Getting hold of the obscure or revised parts of the manuals (if there ever were revised manual versions) is obviously a different matter.

Lex check your board number and if you find you haven't got the exact equivalent pdf file with or without the 5 on the end then I can email you the alternative version if I have it and if you want it!

[cosaw]

Hi guys - further to my last post. Try and get your head round this:



The key for us seems to be the first sentence. It seems because of this line dependancy adjustments at differnt frequencies are needed for optimum performance or "tracking" across the frequency bandwidth. Presumably then Graphics grade machines have more adjustments still. It seems then that the coil adjustment is the base adjustment so to speak and any trim pots thereafter are for keeping the linearity good as the scan frequency increases. Thats what I got from it anyway but not sure if I'm right!

Ok well i've done the deflection and adjusted started playing with this pot, but unfortunately it takes it the wrong direction and won't correct it.
At the mo I've got about 5 1/2 inches on the right between grids and about 5 inches on the left, so it's not exactly noticeable.

I guess I need to find t1 and adjust that, so I'll have to keep pulling the board out and making little adjustments to it - unless someone has another suggestion.

[cosaw]

[FONT=Times New Roman]Lex have you got the precise board number? Like I said in my experience some of these boards are different and the controls can be back to front or there can be 3 adjustments - 2 pots and 1 coil. Worth finding if you've got the 2 pots instead of the 1 before you start playing with the coil. [/FONT]

I'll post it as soon as I'm near the beast!

Board number is 7617415... so are there pdfs for all the different boards then?