CurtPalme.com Home Theater Forum

[kschmit2]

Mechanical Astig Adjustment (C.P.C Magnet Adjustment)

2-pole magnets are those closest to the neckboards, 4-pole magnets (and then 6-pole magnets if present) are closer to the tube bell.

preparatory steps:

1. set ASTIG OUTPUT to your installation type (usually: CEILING FRONT). Changing this setting automatically degausses the projector. To get to the ASTIG OUTPUT setting press ADJUST, enter service passcode, go to OPTION, ENTER, ASTIG OUTPUT, ENTER, choose setting
   
2. set ASTIG ADJUSTMENT to ON. You find this setting in the same menu as ASTIG OUTPUT
   
3. switch to the highest combination of refresh rate and resolution that you will later use
   
4. do lens focus as good as possible
   
5. set blue defocus switch to off (deflection board)
   
6. center electronic focus controls
   
7. set electrical focus using the pots on the deflection board
   
8. For core centering you may have to use 100% contrast or enough that you can see it. IIRC you can also lower brightness a bit to put less stress on the phosphor. In any case: make sure you don't take too long if you do it at normal brightness levels and 100% contrast. While the defocussing greatly reduces the chance of burn-ins, you should better be safe than sorry
   

C.P.C magnet adjustment (look at the dots in the center of the screen for these adjustments)

1. use a dot test pattern (either the internal one, or one from a test pattern generator or PC test pattern application)
   
2. take center focus to +100% on the tube that you are working on
   
3. Adjust the 4-pole magnet to make the dot pattern round
   
4. take center focus to -90%
   
5. adjust 2-pole magnet to make the center core of the dot fit the center of the flare
   
6. adjust center focus (using the remote) to best possible focus, i.e. make the flare disappear from the spot.
   
7. adjust edge focus (using the remote, select edges using CTRL + left, right, up or down arrows) to best possible focus
   
8. adjust corner focus (using the remote, select corners using CTRL + left, right, up or down arrows) to best possible focus
   
9. set brightness and contrast back to their normal levels
   

Note:
the C.P.C Magnet Adjustment has an effect on raster centering (Center Magnet Adjustment), as well as electronic Astig and electrical focus.
So you will have to re-do those, and probably revisit the C.P.C Magnet Adjustment after that again. It really is a back and forth, and only when everything is set up perfectly will your PJ look best.
The end result will be a perfectly round dot.
This is also the reason why we tell users to leave these settings alone, unless they know they are misadjusted.



Electronic Astig Adjustment:

• adjust the ASTIG CROSS (CTL+FOCUS) of the remote control so that the beam is circular at the selected points on the screen (select top, bottom, left and right using CTRL + left, right, up or down arrows).
  
  

• adjust ASTIG CORNER (CTL+FOCUS to toggle between ASTIG CROSS and ASTIG CORNER) of the remote control so that the beam is circular at the selected points on the screen (upper left corner, upper right corner, lower left conrner, lower right corner using CTRL + left, right, up or down arrows)
  
  

(for reference only) ASTIG Operation:
When ASTIG is selected, test pattern dots are automatically displayed, and the beam is defocussed
ASTIG has two directions of operation, which are displayed as HV and SK on the screen.
When HV and SK are changed, their beams will change as shown below:




Final step:
set Blue defocus switch on the deflection board to ON

Kai

[kschmit2]

Please chime in, I'll correct any possible errors.

I would also like to add the necessary info for the XG series, or make a separate guide.


There is an additional preparatory step:
Adjust ASTIG CENTER H/V adjustment control until the top and bottom of the picture look like this:


The XG also has triangularity (6-pole magnets) as an additional step for C.P.C magnet adjustment. That step would be inserted between steps 3 and 4 of C.P.C magnet adjustment.
Also the XG service manual recommends working at 100% contrast with black back raster and each color at bright bias, then 75% contrast and an underfocus state using VR9002. This is slightly confusing, so I didn't want to add that info.
With regard to ASTIG adjustment the XG also has an additional adjustment: ASTIG CENTER (also ASTIG CROSS is called ASTIG EDGE on the XG)

[jask]

nice work Kai.
I would add , anyone who is doing this and has any noticeable imbalance to one side or edge should check the physical setup for misalignment.

[Bert Randolph]

Kai,

very nice description! I will revisit this thread when I finally have the time to do mech. astig with my XG

Daniel.

[hansilili]

Hi Kai,

could you please post a screenshot of the round dots in the corners of a PGxtra? I only manage to get more or less even triangles.

Thanks
Hans

[kschmit2]

heh, I wish I could

No Xtra in da house

[MikeEby]

Nice Job Kai,

Mike

[Mark_A_W]

[hansilili]

[kschmit2]

blue cannot be adjusted electronically, and it isn't really required either, as you have to run it defocussed anyhow

[dropzone7]

Very nice! If I ever get my XG running again I would like to try this.

[kschmit2]

I'll have to add updates for the XG first

[dbaisey]

There is a fine line on the mechanical adjustment and if it has all the parts it was intended to have. If your missing the focus alignment sleeve then you will have issues.

If you have the cpc cluster nulled and electronic astig set to 0/0 you should have the egg shape running in the top to bottom direction at screen center. This needs a look at because you can rotate the focus yoke just a bit to make the corrections before starting. The doc 'tube replacement' I think in the advanced set up should cover this. http://www.curtpalme.com/CRT_Tube_Replacement.shtm

Gravity, deflection board swing down tray all play a part in getting it right. The mechanical astig is all about getting the screen center done right AFTER any position and raster centering is done, phase will also have to be perfect and not changed after the initial phase is done. Move the raster you will change the mechanical 2 pole astig the most. Doug

[kschmit2]

Doug, I'll add the yoke rotation to the guide.

It's mentioned in step 28, fig.1 of the XG Tube Replacement procedure you mentioned (and that's what I refered to in my 2nd post).
But there also is a more in-depth description in the Method of Adjustments section 3.3 (page 10-16) of the XG 751/1101/1351 service manual.
I'm planning to base the steps on that description.

Thanks for chiming in. I really appreciate that.

I'll mention Phase, and the effects of the deflection board swing down tray, as well as the effect the PJs cover will have on the adjustments.

Kai

[rickycleung]

Nice work. Any updated on this guide for XG.

Thanks

[kschmit2]

give me some time.

Maybe I can do it later tonight or tomorrow