Return to the CurtPalme.com main site CurtPalme.com Home Theater Forum
A forum with a sense of fun and community for Home Theater enthusiasts!
Products for Sale ] [ FAQ: Hooking it all up ] [ CRT Primer/FAQ ] [ Best/Worst CRT Projectors List ] [ Setup Tips & Manuals ] [ Advanced Procedures ] [ Newsletters ]

 
Forum FAQForum FAQ   SearchSearch   MemberlistMemberlist  Photo AlbumsPhoto Albums  RegisterRegister 
 MembershipClub Membership   ProfileProfile   Private MessagesPrivate Messages   Log inLog in 
Blu-ray disc release list and must-have titles. Buy the latest and best Blu-ray titles to show off in your home theater!


Any reason focus yoke can't be in front of convergence yoke?

 
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors
View previous topic :: View next topic  
Author Message
CRT_Ben



Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia


PostLink    Posted: Tue Sep 02, 2008 11:44 pm    Post subject: Any reason focus yoke can't be in front of convergence yoke? Reply with quote


        Register to remove this ad. It's free!
Oddball question, I know. But I'm thinking that it might help focus my oddball LUG copies a bit better, so I'm curious to try it out. I assume it wouldn't damage anything for long-term operation?
Back to top
tse



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


PostLink    Posted: Wed Sep 03, 2008 12:16 am    Post subject: Reply with quote

That doesn't sound like a good idea. I recommend using old tubes that you don't mind destroying before trying with good tubes.

Scott

_________________
"Were we directed from Washington when to sow and when to reap, we would soon want bread."

Thomas Jefferson
Back to top
ecrabb
Forum Moderator


Joined: 13 Mar 2006
Posts: 15909
Location: Utah

TV/Projector: JVC RS40, Epson 5010


PostLink    Posted: Wed Sep 03, 2008 12:40 am    Post subject: Reply with quote

I'm totally guessing, but I would think you'd NEED to focus (shape) the electron beam before you could deflect it. Otherwise, how can you possibly focus it if it's already being deflected all over the place? I would guess focus and convergence would both be dorked.

SC
Back to top
View user's photo album (10 photos)
CRT_Ben



Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia


PostLink    Posted: Wed Sep 03, 2008 12:44 am    Post subject: Reply with quote

ecrabb wrote:
I'm totally guessing, but I would think you'd NEED to focus (shape) the electron beam before you could deflect it. Otherwise, how can you possibly focus it if it's already being deflected all over the place? I would guess focus and convergence would both be dorked.

SC


Hmm, good point. I think I'll abandon this idea.
Back to top
Chuchuf



Joined: 11 Mar 2006
Posts: 548



PostLink    Posted: Wed Sep 03, 2008 4:45 pm    Post subject: Reply with quote

Ben,

If you want to try something on your 9500 to improve the focus, Galen did this thing of moving the focus coil further forward by cutting off the mounting tabs on the rear of the deflection coil which allowed the focus coil to slide further forward on the tube neck.. By doing this I believe he was able to get better edge focus with much lower numbers.
Mind you this was done with KD22-22 focus coild so I don't know what the difference if any would be on stock focus coils.

Terry
Back to top
zGman



Joined: 22 May 2006
Posts: 599



PostLink    Posted: Wed Sep 03, 2008 5:31 pm    Post subject: Focus coil experiment Reply with quote

Hi,
This seems like a worthwhile experiment for Ben to consider -
the convergence yoke is not needed to test the focus, and not hard
to remove, with some care it will separate from the deflection
yoke. With the conv yoke removed there will be plenty of room
to slide the focus coil around in search of the best performance.
This could be done on just one tube, and will let you know if the
focus can be improved on these tubes, and if so - then you can
look for ways to get there.
I am assuming you are already using the correct 9" coils, I am
pretty sure Terry found that 8" focus coils wouldn't focus 9" tubes.
Regards,
Galen
Back to top
CRT_Ben



Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia


PostLink    Posted: Wed Sep 03, 2008 5:39 pm    Post subject: Re: Focus coil experiment Reply with quote

zGman wrote:
Hi,
This seems like a worthwhile experiment for Ben to consider -
the convergence yoke is not needed to test the focus, and not hard
to remove, with some care it will separate from the deflection
yoke. With the conv yoke removed there will be plenty of room
to slide the focus coil around in search of the best performance.
This could be done on just one tube, and will let you know if the
focus can be improved on these tubes, and if so - then you can
look for ways to get there.


Terry, Galen,

Thanks for the suggestions - I'm going to give that a shot and see what I can do with modifying the deflection yoke. Before I do though I'll test as Galen suggests and see if moving the coil farther forward helps the focus (with the conv. yoke off the tube entirely).

zGman wrote:
I am assuming you are already using the correct 9" coils, I am
pretty sure Terry found that 8" focus coils wouldn't focus 9" tubes.
Regards,
Galen


Embarassed I am still running the 8" coils...I wonder if Curt has any to swap?
Back to top
Gino



Joined: 22 Apr 2006
Posts: 1363
Location: Trinity Beach, AUSTRALIA


PostLink    Posted: Thu Sep 04, 2008 1:17 am    Post subject: Reply with quote

interesting, looking forward to hearing how this works out
_________________
( B ) ( G ) ( R ) Blendzilla Down Under ( R ) ( G ) ( B ) - Tubes of Fury
Back to top
David_Web



Joined: 02 May 2007
Posts: 418
Location: Sweden


PostLink    Posted: Thu Sep 04, 2008 9:10 am    Post subject: Reply with quote

Sounds like a good plan as you usually don't 'need' convergence on green anyway.
Unless you want perfect geometry that is.

If it goes well for you I might try it as well.

_________________
SNR of people are ridiculously low.
Back to top
Graham Johnson



Joined: 07 Mar 2006
Posts: 241
Location: Melbourne Australia


PostLink    Posted: Thu Sep 04, 2008 9:21 am    Post subject: Reply with quote

Moving the focus coil back and forth changes the electronic focus centre.

Have a look at a BARCO. One of the focus steps is to centralize the electronic adjustments. Then slide the focus coil back and forth for best focus.

Net result is NO advantage.

_________________
Graham
Back to top
David_Web



Joined: 02 May 2007
Posts: 418
Location: Sweden


PostLink    Posted: Thu Sep 04, 2008 10:01 am    Post subject: Reply with quote

Are you sure?
By moving it back and forth and compensating electronically you change the focal length of the magnetic lens. This must have some sort of impact.

_________________
SNR of people are ridiculously low.
Back to top
Chuchuf



Joined: 11 Mar 2006
Posts: 548



PostLink    Posted: Thu Sep 04, 2008 12:40 pm    Post subject: Reply with quote

Graham Johnson wrote:
Moving the focus coil back and forth changes the electronic focus centre.

Have a look at a BARCO. One of the focus steps is to centralize the electronic adjustments. Then slide the focus coil back and forth for best focus.

Net result is NO advantage.


Huh?? If I am reading you correctly, that just isn't true.
Take and set you center electronic focus to 50 on your Barco. Loosen the focus coil and slide it back and forth on the neck. What happens? The focus changes. You then set the coil position for best focus at 50.
I guess what you are saying is that you won't really get a sharper focus from this? But it will certainly change and you can center you controls with this procedure.
With Galens mod, he said he was able to produce a better corner focus (not center) with a much more centered electronic control in the corners.
In Bens case, he is fighting these non-standard tubes that Johnson sold him that weren't really designed for the Marquee and he can't achieve focus on. So I think it would be a worth while experiment on his green tube to see if positioning the focus coil further forward will help him achieve focus.
I have doubts he will ever get a good focus out of these tubes.

Terry
Back to top
Chuchuf



Joined: 11 Mar 2006
Posts: 548



PostLink    Posted: Thu Sep 04, 2008 12:47 pm    Post subject: Re: Focus coil experiment Reply with quote

zGman wrote:
Hi,
I am assuming you are already using the correct 9" coils, I am
pretty sure Terry found that 8" focus coils wouldn't focus 9" tubes.
Regards,
Galen


The one brief experiment I did with the 8" focus coils was interesting. Same part number as the 9" focus coils but couldn't achieve the same focus on a 9" tube as the 9500 focus coils. Kind of wierd. And as I said I only did it once on one tube so I wouldn't consider it to be a fact.

Terry
Back to top
Gino



Joined: 22 Apr 2006
Posts: 1363
Location: Trinity Beach, AUSTRALIA


PostLink    Posted: Thu Sep 04, 2008 1:06 pm    Post subject: Reply with quote

That's strange. So are you saying all those who want to do 8500 to 9500 conversions should get the 9500 magnetics also?
_________________
( B ) ( G ) ( R ) Blendzilla Down Under ( R ) ( G ) ( B ) - Tubes of Fury
Back to top
zGman



Joined: 22 May 2006
Posts: 599



PostLink    Posted: Thu Sep 04, 2008 4:16 pm    Post subject: Marquee 9" Focus coil - Part #'s Reply with quote

Hello,

I just checked two sets from 2002/3 model year.

9" coils -
rdf: 21.696.01P
type: 9251.24
n/s: 146 F 4

8" coils -
P/N: 9251.51
C/N: 21.695.01P
S/N: 00008 K 3

Barco also uses different part #'s for 9" machines.

I think that somewhere a while back tse mentions there was
a different initial calibration of the magnetic field strength for
the permanent magnets, which do most of the work.

From my experiments and experience, the better you can
get the center focus without using the electronic controls
(ie setting electronics to midposition) the easier it is to
get the outer zones to come in with less electronics.
And the less the outer zone focus is used, the less chance
you will get those strangely twisted scan lines at the edges.

1292 coils do benefit from being further foward, I machined
the housings to a snug fit over the clamping tabs of the conv
yoke(with the clamp removed), which gave me about 8mm.

MarkH in Oregon also tried this with good results, he was happy
to finally get his corners to come in.

I also found that the 1292 coils seem to work better when they are not
reversed in their housings. Which stands to reason, why would Sony
go to all that trouble and then install it backwards?

Regards,
Galen
Back to top
Display posts from previous:   
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors All times are GMT
Page 1 of 1
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum