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David_Web
Joined: 02 May 2007
Posts: 418
Location: Sweden
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| Posted: Tue Aug 18, 2009 4:09 pm Post subject: External PSU? |
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The quad decoder is useless so I though I would use the space for something useful and lessen the load on the LVPS.
So I though I would install a P14 switch just in case something where to happen.
Then I thought why not make a proper PSU for it that is properly regulated. Maybe with additional features like pre-heat and current limiting at cold start(if needed, maybe resistor?). Less noisy as well.
Is the filament disconnected from the rest of the tube (floating) or grounded in some way?
I also don't have to worry about LVPS burning the tubes down the road. Less load as well.
How about a separate PSU for the VIM? Noiseless power always seems to improve performance. And the Marquee has a video chain that goes directly to VNB it might be of great benefit.
+-15V if I got it right. Not sure what pins it should be fed to though. +-5 or 6V as well if I remember right.
VNB might be a good idea to leave alone. With all that protection that needs to work.
Is there any other place that might benefit from separate power?
Or additional fans as I have a bunch laying around.
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Tue Aug 18, 2009 4:45 pm Post subject: Re: External PSU? |
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| David_Web wrote: | The quad decoder is useless so I though I would use the space for something useful and lessen the load on the LVPS.
So I though I would install a P14 switch just in case something where to happen.
Then I thought why not make a proper PSU for it that is properly regulated. Maybe with additional features like pre-heat and current limiting at cold start(if needed, maybe resistor?). Less noisy as well.
Is the filament disconnected from the rest of the tube (floating) or grounded in some way?
I also don't have to worry about LVPS burning the tubes down the road. Less load as well.
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A Marquee no doubt. Filaments do not shut off when the projector is off, they run 3.9 vdc if off then rise to 6.35vdc when on.
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1031
Joined: 22 Mar 2006
Posts: 657
Location: Finland
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David_Web
Joined: 02 May 2007
Posts: 418
Location: Sweden
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| Posted: Sat Aug 22, 2009 8:59 pm Post subject: |
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Thanks for the links.
External PSU for fans is not bad. Might lower some noise as well. I guess I could put a fan controller to lower the speed of the fans a little as well as my Marquee don't seem to get hot at all. But it might change when I max raster with the new tubes. Better keep the deflection coils cool.
That P14 mod sounds interesting. Any details?
I should have anything I need to build a good PSU. Boxes of caps laying around as well.
I think I will stay away from the 85V though.
What is the power draw for the different parts?
I wonder if using something like the LM317 as a reference for a power mosfet or npn would work nicely. Lots of different PSU designs to dive in to.
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