CurtPalme.com Home Theater Forum

tse · Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.

At one time 480i was used very much for video viewing. The two deflection coils that make up the horizontal section of the yoke could be in parallel at 15.750kHz but the linearity would be terrible. Look at an Ampro horizontal deflection board and you will see three linearity coils. That is what it took to make linearity good at 15.750kHz with the coils in parallel. The Marquee used a more elegant solution by connecting the two horizontal windings in series at the lower sweep frequencies. The horizontal linearity was much better that way. The linearity was not so bad above 60kHz with the coils connected in parallel and it lowered the flyback voltage with the shorter retrace times that are used at the higher sweep rates. There is really nothing to be gained by messing with different series/parallel arraignment of the windings. The Marquee HDM is designed with the best set of compromises available.

Scott

Ile · Posted: Tue Sep 07, 2010 7:48 am Post subject:

Would banding be even more reduced with also low band coils removed?

mp20748 · Posted: Tue Sep 07, 2010 12:45 pm Post subject:

David_Web · Joined: 02 May 2007 Posts: 418 Location: Sweden

As the mod increase the width as well I take it it's a good idea to decrease width before you mod the board.

mp20748 · Posted: Tue Sep 07, 2010 1:22 pm Post subject:

Ile · Posted: Tue Sep 07, 2010 1:25 pm Post subject:

mp20748 · Posted: Tue Sep 07, 2010 1:45 pm Post subject:

Ile · Posted: Tue Sep 07, 2010 2:40 pm Post subject:

mp20748 · Posted: Tue Sep 07, 2010 2:50 pm Post subject:

Oh, now I understand what you were asking about the coil. I was thinking across the yokes.

There's a diode and 3w 330ohm resistor in series across the coil.

ronaldus · Joined: 25 Dec 2010 Posts: 183 Location: france

Hi Everybody,

I just got a few parts from Ebay (IR sensor, HV splitter, LVPS, CONV amp, V amp, FOCUS and HDM) and on the HDM I saw that some width coils were taken off but also the relays that switch them. The guy where i bought them from seems to be reliable (he had an ultra that he sold and this where his spare parts that he never needed)

I've read this thread off course but before blowing up my projector I would like to know if I could try this with confidence in my own projector. It was not clear to me if I could use this board without the relays.

Could anybody shine a light on this?

Regards,

Ron.

barclay66 · Posted: Wed May 23, 2012 7:33 pm Post subject:

Hi,

If relays and width coils have been removed, this HDM might only work with specific resolutions (= specific Horizontal deflection frequency) or not at all. For each color there are two adjustable coils. One is for low resolutions (H-frequency below ~35kHz) and the other set is for any resolution above. Three relays switch the coils and two other ones switch parts of the deflection circuit (especially the three MOSFETs on the heat sink) in order to compensate for the deflection yoke's frequency dependent current draw.
I wouldn't use such an HDM without knowing exactly what this modification was intended for and which restrictions I'd had to follow when using it.
Post a picture of it here if possible. We might be able to find out which remaining frequency range has been left usable...

Regards,
barclay66

ronaldus · Joined: 25 Dec 2010 Posts: 183 Location: france

Hi again,

I'll try to post a picture when I'm home from work. It's only the 3 relays for the width coils that are taken out as far as i could see.

I've attached a screenshot of the picture from Ebay but it's not very clear but i think you can see which coils have been removed.

I think myself that it has been modified for High scan rate (1080P etc)

two better pics added

regards,

Ron.

barclay66 · Posted: Wed May 23, 2012 11:03 pm Post subject:

Hi,

The coils have been taken out and have been replaced with jumpers. That's the same as adjusting them to maximum width. Seems as if the previous owner tried to get maximum width at high scan rates (which mysteriously alignes to this thread's title!). Take a look at this pic: http://www.etechvideo.com/images/Tip9/Tip9_19.jpg

It still has to be verified which relay setting has been left. Are there any jumpers where the relays used to be?

BTW: The Horizontal Daughter Board is missing. Without it You won't be able to use the HDM anyway!

Regards,
barclay66

ronaldus · Joined: 25 Dec 2010 Posts: 183 Location: france

Thanks barclay

I'll take the daughterboard from my other HDM when i'll try this one.

by the way there are no jumpers where the relays should be. There are just the resistor and capacitor that are normally there when the relays are in.

My other HDM has the problem that it can not give max width when working at 50 Hz refresh rate. (at an H size of 35% it stops increasing in width) This should not happen and should not be related to porch settings

regards,

Ron.

barclay66 · Posted: Thu May 24, 2012 11:47 am Post subject:

ronaldus · Joined: 25 Dec 2010 Posts: 183 Location: france

Hi,

I've tried with the jumper in and out and the width is exactly the same. only the saturation point changes (max width at 25% instead of 35%).

I have not touched the width coils (i'm afraid of creating ringing)

Regards,

Ron.

barclay66 · Posted: Thu May 24, 2012 2:00 pm Post subject:

Hi,

I see. Then it really could be an issue on the HDM creating this effect. When talking about the picture width, You're looking at the tube faces directly, right? Under normal conditions it should be possible to increase the picture width until the raster on the tube reaches the tube's edge. Otherwise the issue could be caused by placing the projector too near to the screen.
From the part number I can see that the HDM is from a 8500/9500 LC (non Ultra). I have one known working and another untested one (each including Daughter Board) which I won't be needing anymore as I upgraded my 9500 LC to an Ultra. So if You're looking for spares just send me a PM...

Regards,
barclay66

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Just get a VP and get rid of ringing that way. I see no use in changing the HDM. Unless you can put each scan circuit right on top of each deflection coil.

Nashou

ronaldus · Joined: 25 Dec 2010 Posts: 183 Location: france

Hi Barclay,

That's exact I'm talking about the tube faces.

I've setup the correct size on the tube faces. (only with 60hz unfortunately) then positioned the screen so that it's correctly filled.

Then later on i discovered that with 50Hz I couldn't fill the screen anymore and thus also the tube face.

I agree that a scaler would be the best but that's also some price tag!

I have a HDleeza that HK-Steve offered to me when I visited him but this thing is not working well with my IP TV set top box (that has a build in Blueray player).

I would love to do 72Hz/75Hz with the leeza to get rid of judder but it doesn't work

My IP TV set top box can scale to 60Hz but it's with judder.

On the other hand If I manage to get 50hz working then I have transformed judder into flicker Smile

I first want to get my projector working as it should (with caps and chips changed so that it's back to specs) and then I'll think about a scaler.

Maybe I can use parts of the HDM from ebay to repair the other one.

I'm into electronics so that's no problem and I'm curious to know what's causing the problem.

Regards,

Ron.

ronaldus · Joined: 25 Dec 2010 Posts: 183 Location: france

Hi everybody,

I just want to post back on the HDM board that i bought from ebay.

I've tested it today (with my own daughterboard and it works better then my own board. I can now fill the phosphor with a 50hz refresh rate and on top of that there are no more vertical lines on the left side of the screen (ringing or banding?)

I'm happy with it and will check if some maintenance mods still have to be done.

regards,

Ron.