CurtPalme.com Home Theater Forum

[damien55]

Hi,


I just scored a Lumagen Vision HDP for 150€ and i can't wait to play with the gamma/RGB adjustement . Before that though, I would like to do the magnetics on the 3 tubes as I have changed a tube a while back and never did it and it looks like things have moved on the other tubes (ex rental projector). For info My projector is a BG808 with HD144 lenses.


So my question is:
How do you know were to place the astig magnet ring, the focus yoke and the deflection yokes on the tube?


I did read a few threads about magnetics adjustements but i never found any info on where to place these 3 parts before begining the adjustements.

To start I guess I will have to reset all the digital astig and focus to midpoint in the menus.
For the deflection yokes I guess have to be as far as possible on the tube (against the tube bell).

But for the two others I have no idea. It looks like when you move one you need to move the other one and that it would take a 1000 years before you find the optimum combinaison.
Do I need to set the astig magnet to 0 before moving them? Do I need to unplug the focus yokes to cancel it's effect?


If someone could explain to me how this is done that would be great.

Thanks a lot

Damien

[damien55]

I try to answer myself.

From the BG808s procedure : http://www.curtpalme.com/docs/BarcoGraphics808s_CRTReplacementProcedure.pdf

It seams like the position for the deflection yoke is against the tube, easy, and that the magnets need to be at least at 2cm from the end of the CRT neck. Then slide the focus unit to maximise focus.

Does that mean that the magnets can be anywhere on the tube as long as they are At Least at 2cm from the neck?
I thought that they had to be adjusted at a precise location to maximise the focus along with the focus yoke (note that I'm not talking about the astig adjutment yet but the position of the magnets along the tube).

Sorry if my questions sound stupid but when changing my blue tube the focus was quite dependant from the position of the magnets along the tube.

Damien

[Ile]

[damien55]

Thanks a lot Ile,

Always here to help me with my BG808!

So if I understand rightI should do:
1/ Position all the equipments on the tube in the right order with the deflection yoke against the bell, the CPC magnets at 2-3cm from the neck and the focus yoke somewhere in the middle.
2/ Put all the magnet rings to 0 (align the tabs) (Not sure if I need to do that)
3/ Switch on and set the focus and astig settings to midpoint in the menus
4/ Level the raster by rotating the deflection yoke
5/ Maximise the focus by moving the focus yoke
6/ Maximise the focus by moving the CPC magnets

7a/Stop there and start following the cpc magnet adjustement procedure (using for exemple the BG808s tube replacement procedure)
7b/ Go back to 5/ and 6/ till you are happy


-So should I skip 2/ at this stage and only reset the magnets after adjusting the positions of the focus yoke and CPC magnets?
-Should I do 7a/ or 7b/ ?
-Or am I totally wrong and will never understand anything about focusing a tube properly


thanks again for your precious help. Hopefully I'll get there

Damien

[Ile]

Deflection yoke against bell, then about 5 mm gap to focus yoke and magnets about 25 mm from neck would be good starting point. I wouldn't worry too much about astig ring position at neck, but if there is focus problems you can try to move it.

If there is factory marker lines at astig rings, turn rings to that line and start there.

Then just follow two last pages of that 808s procedure.

Good result should take about 30 minutes.

[damien55]

Thanks,

I shall try that.

[tse]

It makes things easier if you "null" the neck magnets by overlapping the tabs like the yellow tabs in the attached pic. Get your focus mag positioned like in the procedure then adjust the stig and flare with the neck mags.

Scott