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scot
Joined: 30 Mar 2006
Posts: 16
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| Posted: Mon Jan 12, 2009 12:44 am Post subject: Electronic focus - Center perfect, sides out and visaversa |
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eh8500lc
I can get my center focus perfect on green at about 37 in the service menu, but then my sides are out. If I adjust back to ~50 my sides are perfect, but my center is off. Adjusting the sides seems to do very little, like the difference is too great.
I'm guessing moving the focus is the next step but there isn't any room forward, only back.
Optical focus is just about perfect. Red and blue are good optically and electronically.
Any ideas?
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Mon Jan 12, 2009 12:51 am Post subject: |
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Look directly into the green tube's lens at close range, AFTER you turn down the contrast. Do the focusing then and see what happens.
If you're able to get good focus on the CRT face but not on the screen, you need to adjust lens tilt via the scheimpflug adjustments,
and also, of course, via the forward focusing ring on the lens assembly. (Edge focus)
If there is no electronic focus, it could be any of several things from a bad focus board to focus coils that aren't plugged in or plugged
into the wrong socket. If it's in the wrong socket, adjusting one color's focus will adjust focus on a different color instead.
CJ
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scot
Joined: 30 Mar 2006
Posts: 16
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| Posted: Mon Jan 12, 2009 1:08 am Post subject: |
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Already verified that it is not the flapping. Definitely electronic focus, and it does focus a "little" when moving the green sides but not enough.
If the focus board was wrong I would think that the center focus wouldn't work? That part works great, only the sides.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Mon Jan 12, 2009 1:28 am Post subject: |
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Are you using Franken yokes that you wired yourself? If so then You have the dynamic and Static focus wired backwards if yo flip the wires for one or the other it should fix it.
That is if you did any rewiring of the focus coil connectors.
If the Static focus on the FCm went bad then it would still focus well in the center but when the dynamic(edge focus) is used it would alter the center, and Vice versa.
Put the greens focus connetor on the red connector on the FCM and cover the red and blue lens with covers so you can adjust global focus and watch only the green, if you try doing just the green via the color control it wil only send info to the green chanel on the FCM so you have to have all colors working together hence the covers.
report back whats happeneing
Athanasios
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Mon Jan 12, 2009 1:30 am Post subject: |
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Hello
I have seen focus boards with a soft failure; they will adjust a little but not to the range needed, try another focus board.
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scot
Joined: 30 Mar 2006
Posts: 16
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| Posted: Mon Jan 12, 2009 1:34 am Post subject: |
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no frankenyokes. ugh. Ok i will swap out the focus board. any issues with an 8000 fb being in an 8500?
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Mon Jan 12, 2009 1:35 am Post subject: |
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Ok I had this Conversation with TSE before and found his reply, I was working on the barco re wind project, and asked him some questions, one answer explains what is happepening. there is a compensation circuit that may have gone bad on your FCm.
| TSE wrote: | Now, when the dynamic/left and right focus amplifier is connected to the magnet it will change the overall static focus (the magnetic field changes). The static focus amplifier has a circuit that compensates for that. If that wasn't there the center focus would change when you make adjustments to the left and right side.
It almost sounds like the compensation circuit is not working right if focus is good without magnet wires connected and static focus setting of 80% is needed to get to the same condition when they are.
Try an experiment: adjust left and right focus while watching the center of the image. It should not change focus.
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Sounds like what's happening to your FCM
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Mon Jan 12, 2009 1:53 am Post subject: |
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| scot wrote: | | no frankenyokes. ugh. Ok i will swap out the focus board. any issues with an 8000 fb being in an 8500? |
Hello
No harm in trying but the 8000 fcm may inherently lack enough range, as it was intended for 34.0 kv anode, not 34.9 kv.
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scot
Joined: 30 Mar 2006
Posts: 16
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| Posted: Mon Jan 12, 2009 2:15 am Post subject: |
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Tim: isn't that true only for 1994 and before (or something like that). I thought that all units were changed into 1995. Mine is a 96, actually an 8111 model if that matters.
nashou: Changing side focus does not change center. It just doesn't change local focus much.
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Mon Jan 12, 2009 3:38 am Post subject: |
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An 8110 is an 8500 with a few less features. It won't have electronic astig and its scan rate is limited in software to "only" 130 KHz horizontally. (Still plenty for 1080p) It'll have the same boards as an 8500, not an 8000.
CJ
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scot
Joined: 30 Mar 2006
Posts: 16
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| Posted: Mon Jan 12, 2009 3:31 pm Post subject: |
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Ok, I'll move those boards over then. What a pain! 
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scot
Joined: 30 Mar 2006
Posts: 16
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| Posted: Mon Jan 12, 2009 9:52 pm Post subject: |
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good call guys. Replaced the board and focus is working again. Nice and sharp all the way around, though it shows how far off my flapping is on green now that the electronic focus is sharp. That I can deal with.
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