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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Mon Nov 14, 2011 9:10 pm Post subject: |
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| Quote: | | Wow, didn't see that until looking at the horz out diagram. Also, a short failure of CR1 on the horz power board and the horz winding is tied directly to the filament supply......and heater.... Shocked |
So running an Ampro is a kind of 'OMG this stuff is working' feeling? 
Unfortunately Ampros are very rare here in europe, it's a pity that I've never met one in person... I'm curious 
_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Mon Nov 14, 2011 10:23 pm Post subject: |
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| gjaky wrote: | | Quote: | | Wow, didn't see that until looking at the horz out diagram. Also, a short failure of CR1 on the horz power board and the horz winding is tied directly to the filament supply......and heater.... Shocked |
So running an Ampro is a kind of 'OMG this stuff is working' feeling?
Unfortunately Ampros are very rare here in europe, it's a pity that I've never met one in person... I'm curious |
It's more like" Good thing these Ampro's never fail" HAHAHAHAHAHA!!!!!! 
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incova
Joined: 27 Nov 2006
Posts: 789
Location: london
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| Posted: Tue Nov 15, 2011 12:02 am Post subject: what sweep would violate that? |
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The filament rail is floating coming out of the LVPS. It then connects to the horizontal winding of the deflection yokes. The DC voltage applied to the h winding goes from about 20V to over 200V over the sweep range 15-105kHz. That means the filaments in the CRTs can be referenced 20 to 200V above ground. The CRT spec allows the cathode to be something like 300V more positive than the filaments but 0V negative relative to the filaments. That can be violated at the highest sweep rates. One (of many) good reasons not to run an Ampro above 80 or 90kHz.
what sweep would violate that Scott? Also would this be applicable to any projector or just Ampros?
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The more I learn
the less I know.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Nov 15, 2011 12:33 am Post subject: |
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This is probably not applicable to other projectors as the filament voltage is not usually tied to anything else. But it would have to be looked at on an individual model basis. I was not even aware of this issue on Ampros until Chip commented on where the filament voltage comes from in an Ampro (you know how he's always causing trouble....LOL ).
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incova
Joined: 27 Nov 2006
Posts: 789
Location: london
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| Posted: Tue Nov 15, 2011 12:42 am Post subject: Ok. |
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Thanks , just worried that I may be pushing my PJ too hard with my porch settings for 1080p.
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The more I learn
the less I know.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Tue Nov 15, 2011 12:45 am Post subject: Re: Ok. |
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| incova wrote: | | Thanks , just worried that I may be pushing my PJ too hard with my porch settings for 1080p. |
When it comes to this question I'll let TSE answer that for you.
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barclay66
Joined: 27 Jun 2011
Posts: 1304
Location: Germany
TV/Projector: Marquee 9500 Ultra
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| Posted: Wed Nov 16, 2011 9:57 am Post subject: |
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Hi,
For those with "Filament Voltage Paranoia" on their Marquees:
You might want to add the two parts highlighted in the modified schematic.
If the regulator IC shortens between input and output or if the regulator circuit fails and the output voltage raises above normal, the suppressor diode will draw a large current and the fuse will blow, thus protecting the tubes.
The fuse value may need to be adapted to the real current draw of the three filaments. As for now it's just a suggested value.
The suppressor diode value may too be changed to 6.8V. I chose 7.5V because the diodes with the suffix "A" have a tolerance of 5% and 6.8V-0.34V=6.46V seemed to me being too close to the operating value of 6.35V...
Regards,
barclay66
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Wed Nov 16, 2011 1:47 pm Post subject: Re: what sweep would violate that? |
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| incova wrote: | The filament rail is floating coming out of the LVPS. It then connects to the horizontal winding of the deflection yokes. The DC voltage applied to the h winding goes from about 20V to over 200V over the sweep range 15-105kHz. That means the filaments in the CRTs can be referenced 20 to 200V above ground. The CRT spec allows the cathode to be something like 300V more positive than the filaments but 0V negative relative to the filaments. That can be violated at the highest sweep rates. One (of many) good reasons not to run an Ampro above 80 or 90kHz.
what sweep would violate that Scott? Also would this be applicable to any projector or just Ampros? |
If your video card set-up doesn't tell you the horizontal frequency you can multiply total lines times vertical refresh frequency to determine the horizontal freq.
Scott
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"Were we directed from Washington when to sow and when to reap, we would soon want bread."
Thomas Jefferson
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Thu Nov 17, 2011 1:39 am Post subject: |
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| macgyver655 wrote: | | This is probably not applicable to other projectors as the filament voltage is not usually tied to anything else. But it would have to be looked at on an individual model basis. I was not even aware of this issue on Ampros until Chip commented on where the filament voltage comes from in an Ampro (you know how he's always causing trouble....LOL ). |
Yep, thats me. I'm just like the mayhem guy on those auto insurance commercials
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Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Fri Nov 18, 2011 8:55 pm Post subject: |
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| tse wrote: | How such a simple thing got so screwed up in the Marquee is a mystery to me.
Scott |
the only machines with burned out tubes had one of these installed. The ones with the blue pot were all fine
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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: Fri Nov 18, 2011 9:30 pm Post subject: |
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| draganm wrote: | | tse wrote: | How such a simple thing got so screwed up in the Marquee is a mystery to me.
Scott |
the only machines with burned out tubes had one of these installed. The ones with the blue pot were all fine |
I don't know if that's true. I think Greg Eisemann said the opposite, and I'm pretty sure I've had both gray and blue pots be bad. I always change them regardless.
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