Hitachi swx20b - Pic of trimpots and guns - where is the fixing screw ? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 33 Old 10-12-2002, 04:10 AM - Thread Starter
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Anyone know where the fixing screw is on the guns ? I'ld like to do a manual focus...

see attached photo.
LL
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post #2 of 33 Old 10-12-2002, 10:36 AM
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There are two kinds of focus (that I know of): optical and electronic.

The optical focus involves moving the lens so it is optimally focused.

Electronic focus involves turning a potentiometer just inside the front ofthe set so the electronic beam inside the CRT is optimally focused (though often blue is deliberately defocused slightly).

There's no focus I know involving moving the CRT itself.

Keep in mind there are lethal high voltages on the CRT.

If you're talking about optical focus, you have to remove the projection screen (above the area you're working on) to get to the setscrew that holds the lens. However, all the recent Hitachis I've seen have been properly focus optically. If you do this, be careful not to overtighten the setscrew when done.

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post #3 of 33 Old 10-12-2002, 01:46 PM - Thread Starter
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Thanks.

Yes, I did the electronic focus using the little dials...

Now I'ld like to do the mechanical focus on the lenses... any additional suggestions on this?

Also.. in regards to the CRT.. I thought there would be 3 CRTs, one for red, green, and blue.. is this not the case? And, when focusing the lenses.. wouldn't I be fiddling pretty close to the CRTs ?
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post #4 of 33 Old 10-12-2002, 03:36 PM
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There are 3 crts - red, blue, green. One lens for each CRT.

The lenses are typically in a separate cavity above the CRT's, so you don't get close to the CRT's at all.

Honestly, I'd suggest leaving optical focus alone because you're likely to be fine from the factory - unless you see some problem that needs correcting.

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post #5 of 33 Old 10-12-2002, 09:24 PM
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Are the focus trimpots the three on top, or the three on the bottom?

What is the "Sky Blue" adjustment?

I wonder if you can adjust for beam spot astigmatism by rotating the magnets on the yokes of the crt's.

A lot to play with if you know what you are doing.
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post #6 of 33 Old 10-12-2002, 10:40 PM
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DiscoSmoke,

But extremely dangerous if you don't know what you're doing. Dangerous to you and the set.

Don't touch Sky Blue - that erases all setting and reinitializes the set. In short - you're hosed.

Don't mix up the focus with the color level. Focus is on the bottom. You might want to tape over the color level pots so you don't mix them up.

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post #7 of 33 Old 10-13-2002, 05:54 AM
 
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YUP,

THOSE YOLK CONTROL THE PITCH AND THE LEVEL OF THE SCREEN TOO..

THEY HAVE A WHITE PAINT LIKE COATING THAT WILL BREAK OFF IF REMOVED, ADJUSTED OR TOUCHED AND WILL SQUEAL ON YOU AND YOUR TWEAKING- THUS VOIDING YOUR WARRANTY.

I AM A TWEAKER, BUT THOSE SCARE ME.

I LEAVE THE MAGNETIC YOLKS ALONE SINCE, IF IT AIN'T BROKE I DON'T WANT TO FIX IT.
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post #8 of 33 Old 10-13-2002, 11:14 AM - Thread Starter
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Ha... I was wondering why there was white goo all over the guns.

That makes a lot of sense.
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post #9 of 33 Old 04-28-2003, 06:08 PM
 
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Quote:
Originally posted by sthong
Ha... I was wondering why there was white goo all over the guns.

That makes a lot of sense.
Yup.

No yolks for me:)
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post #10 of 33 Old 04-28-2003, 06:19 PM
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[quote]Originally posted by sthong
Anyone know where the fixing screw is on the guns ? I'ld like to do a manual focus...

see attached photo.
[/QUOTE They actually say on the side which 3 are which in print. The focus is the bottom 3 on mine, one for each color gun. Maybe I am missing the question because your question is for one, and there are 3, and quite in view right when you open it up.
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post #11 of 33 Old 04-28-2003, 07:22 PM
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To perform a mechanical focus, you need to get access to the top of the CRTs by removing the screen. Each CRT has a rim which can be rotated to adjust focus and is held in place by a wingnut.
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post #12 of 33 Old 05-06-2003, 05:16 AM
 
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Do a search... there was a couple good posts running on the subject

Search the words "Hitachi" and "focus"
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post #13 of 33 Old 11-09-2003, 11:03 AM
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ok....i want to do the focus that does not involve taking screen off...which one is that ?? electronic??and if that is correct , then dioes it involve using the trimpots in the picture at beginning of thread?.......and if that is true can someone please tell me how i would know that i would need to do it? I have dve disc for calibration and im guessing that one of the calibration patterns would help me i just need to know how....thanks for any help you can give me!!!

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post #14 of 33 Old 11-09-2003, 05:18 PM
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You can perform mechanical focus without removing the screen by opening a panel on the back of the set.

Focus can also be done from the front without completely removing the screen, you can raise the screen up 6 inches. This is better if you are alone doing focus.

From the rear, I recommend someone at the front helping to confirm focus.

Electrical focus is done by removing the front panel. Be sure not to touch the SCREEN VRs...only FOCUS.
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post #15 of 33 Old 11-09-2003, 06:11 PM
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those are top 3 trimpots right?
what do they do?

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post #16 of 33 Old 11-09-2003, 08:09 PM
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make sure to mark all those pots with a colored pen or paint pen so you can always go back to the original setting even if you screw up.
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post #17 of 33 Old 11-09-2003, 08:30 PM
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what do the screen vrs do?

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post #18 of 33 Old 11-09-2003, 09:25 PM
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This thread is just disturbing. :eek:

If you have to ask, you shouldn't be doing it! Don't come back on anyone who suggested advice and say your set is screwed up.

Quick Reference of Forum Rules
1) Do Not post pricing you found on-line or at a local dealer UNLESS IN A DEALS THREAD.
2) Do Not ask for, or offer, a receipt so people can price match.
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post #19 of 33 Old 11-09-2003, 10:32 PM
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if you think this one is disturbing then wait till you read some others!!lmao

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post #20 of 33 Old 11-10-2003, 06:13 AM
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Quote:
Originally posted by frenchmarky
make sure to mark all those pots with a colored pen or paint pen so you can always go back to the original setting even if you screw up.
If you touch the SCREEN pots, there is no going back (not fully at least). These will affect your gray scale.

The good news is, your grayscale wasn't accurate to begin with. If you screwed with them, it is a good excuse to get your grayscale professionally calibrated.
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post #21 of 33 Old 11-10-2003, 01:18 PM
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I will change my recommendation to use a tiny sliver of masking tape instead of something that could not be removed like paint or ink...anyway it should be pretty accurate to go back to the same spot if you make a goof. As long as you carefully and accurately align the sliver with the slot you should be ok. What is the reason you are saying you can't go back? thanks...Frenchy
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post #22 of 33 Old 11-10-2003, 01:51 PM
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Quote:
What is the reason you are saying you can't go back?
Because of the extreme sensitivity of these pots. Just don't touch them...what's so hard about that?
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post #23 of 33 Old 11-10-2003, 03:15 PM
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thanks a lot man.....I think i did touch the one under the green focus...ubut just a little....maybe...lmao....i dont think i touched it....or did i???


this post will really disturb trhat last guy.......

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post #24 of 33 Old 11-10-2003, 04:20 PM
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LOL...you crack me up deez

...just pretend you didn't touch it. Since grayscale isn't accurate out of the box anyways, you are alright as long as you don't notice a glaring error in your grayscale.

I have the Hitachi service manual and it actually instructs technitions to calibrate it to 10,000K. Unbelievable!!!
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post #25 of 33 Old 11-10-2003, 07:57 PM
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lmao....10k highlarious!!!

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post #26 of 33 Old 11-10-2003, 08:41 PM
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Golly gee, I was just askin', common practice on tvs and such to mark pots before adjusting them, didn't know these were that goldarn sensitive. If you accurately mark a pot with a sharp, precise marking and put in exactly the same place it should have the same value as before unless it is a real cheap crappy pot, or it's dirty, or unless the pot has some huge range on it which these usually don't....apparently you are as touchy as these pots are....Frenchy
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post #27 of 33 Old 11-13-2003, 09:01 PM
 
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Set the greyscale values to factory defualts.... and eyeball the color pots or trimpots...

Then adjust the cuts and drives afterwards to perfect it.

Takes some experience to get it right without equiptment though...

Most people who have the skill to eyeball it and do a good job usually don't mess it up in the first place...

And people who don't have the experience.... thier tv turns out green or pruple....

Greyscale really should be perfected by and ISF guy with equiptment.
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post #28 of 33 Old 11-13-2003, 09:11 PM
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Quote:
Originally posted by frenchmarky
Golly gee, I was just askin', common practice on tvs and such to mark pots before adjusting them, didn't know these were that goldarn sensitive. If you accurately mark a pot with a sharp, precise marking and put in exactly the same place it should have the same value as before unless it is a real cheap crappy pot, or it's dirty, or unless the pot has some huge range on it which these usually don't....apparently you are as touchy as these pots are....Frenchy
They are just that sensitive. On the Mits sets, there are procedures to set these with a oscilloscope or voltmeter to a specific voltage. You would not believe just how sensitive they are. It is unfortunate that Hitachi's procedures are completely unscientific. The method Mike posted above is probably better than what Hitachi specifies.
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post #29 of 33 Old 11-13-2003, 09:19 PM
 
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Quote:
Originally posted by Marc Alexander
The method Mike posted above is probably better than what Hitachi specifies.
And to think that I put little effort into even explaining myself clearly.... Makes this Sad but True.
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post #30 of 33 Old 11-14-2003, 05:20 PM
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i love this "DISTURBING" thread!!lmao

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