CurtPalme.com Home Theater Forum

amigaman

Hello all.

I'm working on setting up my NEC XG-75A for 16:9 1080p, from a Moome DVI/component card. I got everything scanning and synced up well, but I would like the raster a bit wider, to more effectively utilize the CRT area.

I read the procedure for calibrating the maximum horizontal amplitude on the horizontal deflection board, but that procedure calls for a 480i signal, and the amplitude decreases when a 1080p signal is applied.

So my question is, can I align the horizontal deflection board with a 1080p signal instead of a 480i one, or might the higher frequency at the same gain damage something? That is, can I set the voltage at pin 1 of IC5306 to 4.5V, and TP5302 to 7.5V with a 1080p signal instead of a 480i one? Of course, I would not align other source presets to exceed the amplitude of the 1080p signal.

I tried it already, and it works, I just want to make sure it won't hurt anything long term.

Thanks in advance.

amigaman · Posted: Wed Mar 09, 2011 4:07 am Post subject:

Any ideas? I'm installing the projector soon, and I'd like to know what I'll have to compensate for.

I read the NEC PG setup guide on this site, and it said not to exceed the amplitude limits of the deflection system, or parts may be damaged. Since I'm not wanting to exceed the size on my XG, only maintain the size it at higher frequencies, would that run the same risk?

If I need to clarify anything, I'd be happy to.

Thanks!

**AnalogRocks** · Posted: Wed Mar 09, 2011 4:09 am Post subject:

You will likely need a scaler to get 1080p to properly fit your NEC. Something like a VP50

amigaman · Posted: Wed Mar 09, 2011 4:23 am Post subject:

I have the Moome DVI/component card, and my computer connected via DVI lists a 1080p option from the card. The projector syncs up just fine, and the 67kHz H and 60Hz V rates are within spec for the projector. The horizontal scale only drops a little bit (about 1/4" on both sides of the raster, looking at the CRT faceplate, not the screen). The 1080p image is also adequately filling the raster, so there isn't excess blanking or anything, leading me to believe that a scaler would not help.

Am I right in thinking that, or am I missing something? This is the first I've worked with CRT projectors at anything but NTSC resolution.

**AnalogRocks** · Posted: Wed Mar 09, 2011 4:42 am Post subject:

Ahhh you're on an HTPC then you can use powerstrip ( provided your video card is compatible ) to adjust the signal timings. Mainly the front and back porches in the video signal to make it 'fit'.

http://entechtaiwan.com/util/ps.shtm

or if you're on an Nvidia card there's a utility to adjust the timings built into the video driver.

amigaman · Posted: Wed Mar 09, 2011 5:13 am Post subject:

That looks like a great program, although I should have mentioned my HTPC is a Mac. Even so though, it's the raster and the image that are a little smaller, not just the image, so wouldn't changing the front/back porches only affect the image inside the raster?

My thought was that this slight drop in amplitude is just the frequency response of the projector's sweep system being slightly less at 67kHz than it is at 15kHz. I can get it where I want it with the horizontal amplitude limit adjust pots on the H deflection board, I'm just wondering if that's a bad thing to do (no voltages are exceeded on the test points on the board).

Basically I want to increase the internal limit, so that at 100% the 1080p matches where the 480i is now, then I would bring the 480i menu adjustment for amplitude down to match the 1080p, so nothing is pushed past the voltage limits on the test points. It's just the higher frequency at that gain that scares me, since I'd image it takes more power to drive the higher frequency at the same size.

Should I just try it that way and see if anything heats up more than usual? Since it's such a small adjustment I would imagine it's ok. Just looking for any potential concerns.

**AnalogRocks** · Posted: Wed Mar 09, 2011 5:23 am Post subject:

DO NOT adjust the projector. If you get one of those pots too far outta whack you'll never get it adjusted right. NEC's are like that. If it needs to be adjusted at 480i then it's 480i only

Since you are on a Mac you need switchXres

http://www.madrau.com/download/latest/latest.html

amigaman · Posted: Wed Mar 09, 2011 5:36 am Post subject:

I'm not one to go in and start adjusting things blindly, but that makes sense. If they bothered to specify 480i, it was probably for a good reason. I'll stick with that procedure then.

Thanks for the link, I'm downloading it now and we'll see if it helps. Looks very useful.

For reference, this is the scale setting procedure I was referring to:

http://www.curtpalme.com/NECXG_Layout1.shtm

I'll stick with that. Better to remain safe and not have a dead projector.

Thanks!

**AnalogRocks** · Posted: Wed Mar 09, 2011 5:48 am Post subject:

friedwart · Posted: Wed Mar 09, 2011 3:57 pm Post subject:

amigaman · Posted: Thu Mar 10, 2011 8:27 am Post subject:

After adjusting keystone, the wider end of the image comes pretty near the CRT edges, so it looks like it's scanning to an acceptable size on the CRTs after all.

Thanks for the input, and the SwitchResX link. Great program!

**AnalogRocks** · Posted: Thu Mar 10, 2011 8:30 am Post subject:

Glad you got it going. How does it look?

amigaman · Posted: Thu Mar 10, 2011 8:40 am Post subject:

Looks amazing so far. The blue tube is fairly worn, so there's a bit of a bluish shift towards the left and right sides, but it's a soft transition, so it's not too objectionable (however if anyone has a spare blue tube they'd be willing to sell that would be amazing). I think they had the phosphor saver turned on, hence the smooth transitions in and out of the wear area. It still white balances well within the wear area.

Compared to my old Sony VPH-1042Q though, it's simply spectacular.