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Discussion Starter · #1 ·
So - I keep reading in various posts about not over-stressing your convergence circuits. So, how much adjustment is too much? 10% of the range off neutral for a given adjustment? 20%? 80%?


I gather this is different from projector to projector, and that setting anything to MAX or MIN (or 0 or 100, or whatever your extremes are) is not a great idea on any unit. But if you are an Experienced Tech setting up a projector you aren't terribly familiar with, say, at what point in making an electronic adjustment would you start to get nervous and think about going back to something in the initial physical alignment?


And is this a cumulative thing, like a lot of little adjustments on every setting adds up to BAD, or does it just matter for a single adjustment (like, setting horizontal red bow to MAX is endangering your horizontal red bow adjustment circuit and ONLY your horizontal red bow adjustment?)


Thanks in advance for any advice. My projector has very comprehensive and easy-to-use electronic adjustments for everything but the kitchen sink, but every time I read about "don't stress your electronic convergence controls" it makes me cringe because I have no idea whether I'm stressing them or not...
 

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Well..... for starters, what projector do you have? Less electrical adjustment with a very solid mechanical alignment also means less drift. Less re-adjusting over time. This only makes common sense. Some projectors are more prone, though. The Convergence drive IC's in NEC's tend to run very hot, and can be made to fail by using extreme adjustments. There are lots of good tips here. Do some searching, and I'm sure others will add their advice here as well.


Marc
 

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If a good mechanical setup, and convergence is done, the electronic convergence adjustments will be minimal.

That is an easy way to tell if good mechanical has been done, just take a look at electronic settings for things like Tilt, Static Convergence, and Vertical Keystonel, the closer to 0 (or center) the better.

In the case of an NEC XG projector those settings can easily be kept to +/- 5...Vertical Keystone was a little tougher, the best I could get that was -12...still not bad.

With correct use of Mechanical Convergence and the Deflection Yoke, electronic Tilt (I think my Ampro calls this H skew?) and Static Convergence on any pj should be very low...installing the pj squared to the screen will help keep V Keystone to a minimum.
 

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Discussion Starter · #4 ·
Thanks for the responses. It sounds to me like I am most definately NOT stressing my projector, as my mechanical setup is pretty solid and tilt and veritcal keystone are things I don't really need to adjust at all. My biggest adjustments are in the linearity of the raster (need to increase both red and blue a little to get the grids to match green) and medium point convergence in the extrememe corners, and not even in all four.


I don't have an NEC, I have a late-model (1996) Panasonic. I love everything about it except the fact not enough people on this forum have them so there's definately a lack of projector-specific information compared to Electrohome, Sony & Barco. Figuring out how to do things like converge with externally generated test patterns, which pots do what, etc. are all trial-and-error discoveries. Fortunately it seems like every CRT manufacturer has built in the same adjustments as everyone else so for me when I read about some tweak on this forum it's just a matter of poking around until I find it...


...which I admit is kind of fun.


Thanks!
 

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Guys!


When in doubt, revisit the fundamental principles. A correctly aligned CRT projector will have all three rasters centered on the tube faces with static positioning correction nulled, most units have some sort of magnetic centering tabs on the CRT necks. Flare magnet adjustment will affect centering also so flare (and stig) must be properly aligned. Sweep yokes must be leveled to each other at the horizon, no twist permitted. Raster widths must be matched, some projectors have low-band and high-band sweep, and two sets of width coils to adjust. Raster heights should be matched with convergence nulled. All of these factors will combine to put the least load on the dynamic convergence and should result in good convergence out to the corners, and the least

possible drift too.
 

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Ahmen.
 

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That is why it is a good idea to reset to the pj's default settings before even starting the mechanical setup.

In fact a nice thing about the unistrut mounting system is you can reset to factory defaults, make sure the Rasters are centered, then position the pj to match most of it's defaut settings...it takes awhile, because centering the pj on the screen, while at the same time adjusting it to be square to the screen can get alittle frustrating...Convergence wise, it seems to be working just as well as my first factory mount system did.
 
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