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jbryngelson
Joined: 02 Jan 2008
Posts: 14
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| Posted: Sun Jan 10, 2010 1:11 pm Post subject: NEC XG Help |
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Hey guys, I have a xg-135 that is overdriving the tubes so I had to retube the thing yesterday with the help of my good friend John Gannon. The reason the tubes were toasted, is the projector is overdriving them. I need to drop the amount of voltage/gain being sent to all of them, not just a Kelvin setting, or a contrast adjustment. I dropped the contrast all the way to 5 and it still was too punchy!
I am looking for the proper POT to adjust so I can get this under control.
When you go into the service menu for the Kelvin adjustment, there is Red and Blue gain, which is the adjustment needed (How much voltage goes to the tube), but non for the Green. I know the Green is the key to all of them, so I need to get it right, and if I recall it is a Variable Resister Pot adjustment.
Suggestions??
Thanks!
Jeff
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sun Jan 10, 2010 5:54 pm Post subject: |
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This usually needs a complete white balance setup.
There is a master contrast/drive board on I think the middle video board, it's labelled on the top cover, but it does throw other stuff off.
Do you know how to do the KennyG white balance? That's what should bring this back into place.
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jbryngelson
Joined: 02 Jan 2008
Posts: 14
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| Posted: Sun Jan 10, 2010 9:13 pm Post subject: Thanks - Got it somewhere? |
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cant seem to find, can you post a link, or the text?
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jbryngelson
Joined: 02 Jan 2008
Posts: 14
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| Posted: Sun Jan 10, 2010 9:16 pm Post subject: |
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Nevermind, I found it, I know it as the G2 procedure, not White Balance...Thanks
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Mon Jan 11, 2010 1:59 am Post subject: |
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Not that I've seen the set, but it bothers me that the set is 'too punchy'. I'd think if max contrast on a 'regular' XG was reached at 75 factory default), and yours is about the same at 50, then you should see massive smearing/blooming at 100 contrast, right?
Maybe the input signal is too strong? What do the internal test patterns look like at 60/75 brightness and contrast? THe stepped gray scale should be a good indication if there's a problem within the set.
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Mon Jan 11, 2010 6:44 am Post subject: |
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There are also the high output mode switches on the HV board.
They add 20% or so.
The contrast pot is called sub-cont I think. DO NOT TWEAK this pot unless you do the whole procedure, and don't do that until everything else is checked first.
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jbryngelson
Joined: 02 Jan 2008
Posts: 14
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| Posted: Wed Jan 13, 2010 4:14 pm Post subject: |
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Hey guys, things are moving along nicely. I was able to get the set to behave with proper adjustment of a few settings. The reference color setting, the user kelvin settings were too agressive, and I found the Green G2 pot that really helped.
I calmed everything down, and now plan to completely delete the memory settings and start from the ground up on this beast, using NTSC as the default which should allow the projector to scale easily when other settings are used (HD and other PC formats). I will fine tune 1080i and 720P to perfection, but other inputs will behave nicely if the default calibration is done properly, and in the right memory slot.
Im off to look up the memory block settings on the XG.
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Thu Jan 14, 2010 3:43 am Post subject: |
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Did you check the switches on the HV board?
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yonexsp
Joined: 25 Apr 2006
Posts: 311
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| Posted: Thu Jan 14, 2010 4:15 pm Post subject: |
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| Mark_A_W wrote: | | Did you check the switches on the HV board? |
What do those switches do Mark? What would you use them for?
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Thu Jan 14, 2010 9:43 pm Post subject: |
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They set the current for the HV.
There is high, normal and low.
In high mode the output is ~20% higher.
If it's in high mode it will seem like the contrast is much higher.
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yonexsp
Joined: 25 Apr 2006
Posts: 311
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| Posted: Sat Jan 16, 2010 1:52 am Post subject: |
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| Mark_A_W wrote: | They set the current for the HV.
There is high, normal and low.
In high mode the output is ~20% higher.
If it's in high mode it will seem like the contrast is much higher. |
What are the merits of each of the settings?
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Sat Jan 16, 2010 1:55 am Post subject: |
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High = Tubes fry
Normal = Tubes last normal
Low = Tubes last long time..
Just leave it on normal, the HV current on an LC projector is already higher than an AC one (one of the few actual board differences).
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yonexsp
Joined: 25 Apr 2006
Posts: 311
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| Posted: Sat Jan 16, 2010 2:01 am Post subject: |
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| Mark_A_W wrote: | High = Tubes fry
Normal = Tubes last normal
Low = Tubes last long time..
Just leave it on normal, the HV current on an LC projector is already higher than an AC one (one of the few actual board differences). |
Cheers mate, I will try low just to see anyway. Not that it matters, as there is enough tube life left for probably 5000hrs on mine and it will have been replaced long before that by a digital. They are getting to chap and to good to put up with the downsides of CRT for much longer (size, noise, resolution).
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