Anyone for some Marquee Maintenance? - Page 4 - AVS | Home Theater Discussions And Reviews
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post #91 of 614 Old 02-12-2003, 09:53 PM
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What would happen if the pot became intermittent or opened completely? The output voltage would still rise. How about putting a 25-ohm pot and 100-ohm resistor in place of R1, and the fixed 470-ohm at R2?

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post #92 of 614 Old 02-13-2003, 01:23 AM
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>>What would happen if the pot became intermittent or opened completely

it will never be more the 20 ohms unless it is burned
and it is just as likely to burn a fixed resistor
and if say the wiper fell off it would be 20 ohms
aka 6.3542V

it is very unlikely to fail.
The original circuit
would have a large voltage shift for a very small movement in the pot. so just a bump or thermal change would cause it to go out of spec. With this mod the whole range is safe. And is makes for very easy rework.
To move the pot to the other side would take a lot more rework.
I do not know why they made it that way in the first place
you are just asking for it to jump out of spec with such a sensitive setting. I guess that why they used a 25 turn pot
if they had made it like this in the first place they could have use a 1 turn with out any problems. I think this was ether a over-site or done so they could replace CRT's and boost service income.. Ether way it is bad practice to have an adjustment move any more then is needed. In fact I do not know why it is there at all they could have just used fixed parts set to 6.35V
the only thing I can think of they might have thought that a 2nd source CRT would use a different voltage??
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post #93 of 614 Old 02-13-2003, 06:30 AM
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Sly

I don't think that is true. I think Electrohome outsourced the power supply to the company in Illinios with a load spec. I don't think this power supply is just in the Marquee. I think it is used in many devices, not just projectors.

Instead of the pot, why not design a circuit, sampling output to use as feed back, to replace the pot. Remember that filament voltage drops to about half when the pj is turned off.

Walt
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post #94 of 614 Old 02-13-2003, 09:21 AM
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Why not just replace the pot with a fixed resitor?
-peter
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post #95 of 614 Old 02-13-2003, 09:47 AM
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Peter
"Why not just replace the pot with a fixed resitor?"

As age sets in the voltage will probably change and you want to maintain the 6.35, if possible, with a little adjustment.

Walt
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post #96 of 614 Old 02-13-2003, 10:11 AM
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But this circuit uses a voltage regulator, so unless the value of the resistors changes (not likley at all) then it should hold the output voltage regardless of the load as long as the load does not go out of spec for the regulator.
I am missing something?
-peter
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post #97 of 614 Old 02-13-2003, 02:39 PM
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Is there a mod or tweak or board/part that will:

a) Increase the light output

b) Increase the resolution rating up to 2200 by 2600 or 2048 by 1536 ansi pixels that you see written in the hi-end magazines for the Reference Imaging/Accurate Imaging "9500s".

Sorry if this is a stupid question or has been already answered.

Also, I was wondering if you experts have a list of products or services/mods that you could do for us newbies for a price and their benefits.
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post #98 of 614 Old 02-13-2003, 05:04 PM - Thread Starter
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Quote:
Originally posted by docajay
Is there a mod or tweak or board/part that will:

a) Increase the light output

b) Increase the resolution rating up to 2200 by 2600 or 2048 by 1536 ansi pixels that you see written in the hi-end magazines for the Reference Imaging/Accurate Imaging "9500s".

Sorry if this is a stupid question or has been already answered.


You'll have to learn how to read those magazines the same way you learned how to eat chicken -- don't chew and swallow the bones.

It's all about the performance... Got Marquee!

High Performance Marquee Video chain modifications. Still available!
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post #99 of 614 Old 02-13-2003, 07:30 PM
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"Why not just replace the pot with a fixed resistor?"

you could but it would be hard to find a 489.6 ohm resistor
And they are a bit off any ways. you might be able to find
a set the would work it it should stay
but there is the spot for a pot and this way you can make it dead-on.

" Instead of the pot, why not design a circuit, sampling output to use as feed back, to replace the pot. Remember that filament voltage drops to about half when the pj is turned off. "

The circuit does have feedback it is the feedback part that make the voltage adjustment.

There does not seem to be any thing to drop the voltage when it is off/standby, so it must be dropping the voltage on the input it the LM117 voltage regulator.

The difference in turning the pot all the way back and forth after the mod will only change the voltage 0.21V
before the mod it would be 10.42V . And this is with easy to get parts of common values. And just one cut on the PCB. I am trying to keep it simple and easy to do. and should never have to be messed with again.
if it moves a few percent over time no big deal
a few percent of 0.21V is very small but a few percent of 10.42 and is a different story.
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post #100 of 614 Old 02-13-2003, 07:44 PM
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OK I just changed my pot to a 485ohm (measures 485) 1% 1/4 watt metal film. The other resistor measures at 120.5 ohms. Using the formula for the lm317 I should see about 6.28 volts.

With the CRT powered up but cool, I measure 6.16 volts on the jumper near the rear of the blue tube. I will remeasure in an hour and see what it is after everything gets warm.

Anyhow if this still hold to be the case that I see 6.16 volts,then I would suggest having a pot etc in series with a fixed resistor as sly suggested such that you can get a total resistance of at least 500 ohms. This should allow more range. I will probably add another 10 - 15 ohms to mine to get to 6.27 or so

-Peter
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post #101 of 614 Old 02-13-2003, 08:01 PM
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120mV is not very much I bet that is the drop in the wires from the regulator to where you measured. ??
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post #102 of 614 Old 02-13-2003, 10:07 PM
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Quote:
Originally posted by sly
120mV is not very much I bet that is the drop in the wires from the regulator to where you measured. ??

This is what I was thinking as well. After two hours the voltage was measured to be 6.15 volts so it is holding steady (watched "Momento" which was a good movie). I will increase my R value to be 500 ohms. This should give a therotical 6.43 volts but if I still see the same 120mv drop/error, then I should be at 6.31 which is close enough to 6.35volts. I will of course report back when I try this out (Probably won't be until tueday though)

-Peter
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post #103 of 614 Old 02-13-2003, 11:21 PM
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Hi Mike,
I just got around to checking out my video neck boards. The red and green boards have the blue soldered on capacitors (looks kinda kludgey) but the blue board doesn't. The all have H1100's and the metal can Q12 and Q19.

Is it normal for the three boards to be different?

thanks,
bruce
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post #104 of 614 Old 02-14-2003, 06:11 AM - Thread Starter
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Yes, that's normal. The Marquee has been in production longer than any other CRT projector, and in the last ten years there have been some changes made. The neck board was the item that had experienced most of these changes, but only the very first boards were a source of problems.

The board that does not have the blue caps soldered on it, would more likely develope the "blanking out on bright scenes" problem. But until that happens and if there is no noticable smearing in the image, leave it be and enjoy.

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post #105 of 614 Old 02-14-2003, 10:47 PM
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yeah, I've got bigger fish to fry first - just discovered that my filament voltage is over 8 volts!!!!!!!!

Good think that less expensive CRT rebuilder surfaced in another thread here - hope it works out that their quality is good ...

cheers,
bruce
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post #106 of 614 Old 02-15-2003, 08:00 AM
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Hi Guy's,

I've got a pic of my VIM below, the upper part shows "U22", but the
RGB jacks are straight. My VIM is layed out different compared to Sly's VIM.
So, to avoid assuming on my part, comfirm for me that I do have the
gamma circuit. Is this what you could call an early version of the newer
VIM?

The lower pic shows R152, this is the resistor to be removed to do
away with sync on green, correct? I just have to hear a yes from someone
before I take that off the VIM. If I'm wrong I don't want to test my skills
getting it back on.

Thanks for starting this thread Mike, your teaching this noob a thing
or two.

Bruce
LL
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post #107 of 614 Old 02-15-2003, 02:51 PM - Thread Starter
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Quote:
Originally posted by bob2010
Hi Guy's,


The lower pic shows R152, this is the resistor to be removed to do
away with sync on green, correct? I just have to hear a yes from someone
before I take that off the VIM. If I'm wrong I don't want to test my skills
getting it back on.

Thanks for starting this thread Mike, your teaching this noob a thing
or two.

Bruce

Yes, take the resistor (200 ohm) out. And if your board has "U22" you have the gamma circuit.

It's all about the performance... Got Marquee!

High Performance Marquee Video chain modifications. Still available!
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post #108 of 614 Old 02-15-2003, 07:17 PM
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Thanks Mike.

Bruce
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post #109 of 614 Old 02-17-2003, 01:59 AM
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if you can't see the images try this
http://www.geocities.com/hvps2001/


I thought I would start off by replacing bad parts on the outside of the potting. I will start off with the G2 control circuits. The resistors in mine were way off and they are carbon type (the worst kind of resistor) they get out of spec if they get hot and they also add white noise.
I think this might be what causes some of the faint snow that has been seen in the background by some people


Start by removing the bad resistors
you can see I have removed one already.
Attachment 156324

All 6 replaced. Attachment 156325

Note the Air gap don't let the resistors touch the PCB. They need air flow for cooling. Attachment 156326

Next I replace the input filter caps. The new caps are smaller so I scraped the solder mask off the trace and just soldered one pin of the cap to the trace.
Notice the burnt white cap..

Now the next 2 caps and resistors and yes those little guys are 2 watt I rechecked when I got them and I even ran 20Volts through them just to test that they are 2 watts Attachment 156327

Notice the air gaps on the resistors the leads help cool them and I have the caps as far as I can get. Attachment 156328

http://www.geocities.com/hvps2001/
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post #110 of 614 Old 02-17-2003, 01:59 PM
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you will see milky white stuff on the left next to the metal.
is anyones working HVPS have this??

image for the post before this.
LL
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post #111 of 614 Old 02-17-2003, 02:09 PM - Thread Starter
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It's on most of them, even the working supplies. I gave up on trying to figure out what it is or where it comes from.

It's all about the performance... Got Marquee!

High Performance Marquee Video chain modifications. Still available!
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post #112 of 614 Old 02-17-2003, 02:32 PM
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When I bring up the convergence pattern at 15.75Khz, it is jittery, mostly in the horizontal direction such that I see three vertical lines for every real vertical line. At any higher frequencies I get a stable pattern. Does this jitter indicate some flaky components? When I look at an NTSC input (say, from a VCR or DVD player connected to the decoder board), I get a pretty good picture with some horizontal jitter at the top of the image. (gotta get working on my HTPC!). Any suggestions?

Also, does the anamorphic squeeze mod also squeeze the overlay graphics (e.g. the slider bar that shows when you click on Contrast). My overlaid graphics are running off the bottom of the screen, and there are some convergence zones where I don't see the box at all.

thanks,
bruce
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post #113 of 614 Old 02-17-2003, 02:33 PM
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For those of you who wants to build up the gamma correction; here it is.


Does it make sense to build a gamma correction for green and red too?
LL

Regards,
Dirk
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post #114 of 614 Old 02-17-2003, 03:45 PM
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Thanks I thought it would be.
it is primer for the potting
see SS4155 http://www.mgchemicals.com/products/...s/primers.html

and I think the potting is/should be TSE3331 HV and Thermally Conductive
http://www.mgchemicals.com/products/3331.html
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post #115 of 614 Old 02-17-2003, 04:22 PM
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Quote:
Originally posted by mp20748
I gave up on trying to figure out what it is or where it comes from.

There are some things better left unknown

Thanks a million...Good luck...Let us know... Whichever is appropriate this time! jmwj03 at hotmail dot com
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post #116 of 614 Old 02-17-2003, 06:11 PM
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If someone can slap together a gerber and BOM I could look at making a small run of these. Would of course give free samples to all who help!
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post #117 of 614 Old 02-17-2003, 06:11 PM
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If someone can slap together a gerber and BOM I could look at making a small run of these. Would of course give free samples to all who help!
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post #118 of 614 Old 02-17-2003, 06:49 PM
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Hey Sly, I'm suprised someone has not asked you yet. What model camera and what resolution are you using for those pictures. Those are outstanding!

I'm going to guess at least 4 megapixels, probably more.

Also, did I get lost here? What parts and numbers are you replacing in these pictures? I can see your heading that states HVPS, but what are the part numbers you are replacing the bad ones with?

Brad
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post #119 of 614 Old 02-17-2003, 07:27 PM
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Quote:
Originally posted by Tester007
If someone can slap together a gerber and BOM I could look at making a small run of these. Would of course give free samples to all who help!

A gerber? I'm thinking the BOM is a bill of materials list...but a gerber? What the heck is a gerber? Did I miss something?

Thanks a million...Good luck...Let us know... Whichever is appropriate this time! jmwj03 at hotmail dot com
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post #120 of 614 Old 02-17-2003, 07:39 PM
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a gerber plot, as in a layout for the PCB
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