CurtPalme.com Home Theater Forum

[CIR Engineering]

Questions for NEC tweakers...

I have here an NEC PG Xtra and a PG+. Both projectors run well.

The Xtra has crispy fried tubes and the PG+ has fresh minty tubes. I know that you can't just swap tubes between the two (I think I know that anyway). However, would it work if I took the full tube assemblies including magnetics and hardware from the PG+ and put that into the PG Xtra? Has anyone tried this before?

Doc gave me these projectors for free instead of throwing them away, and I am setting one up for a friend of mine FREE of charge. Do you think swapping the tubes is worth it, or should I jsut give him one or the other of the projectors.

The tube wear is heavy on the Xtra, but if I stay inside the wear pattern the projector still look good. Attached are screen shots of the Xtra on a piece of wrinkled black out fabric taken with my crappy camera... so it looks MUCH better in person.









Not bad for burnt tubes eh? Maybe I should leave well enough alone!

craigr

[Curt Palme]

Craig, pink looks good on you!

Try it. I haven't.

My next experiment is to try Xtra system boards in a PG+. I am completely out of PG+ system boards, and need a test chassis....

[Curt Palme]

Craig, pink looks good on you!

Try it. I haven't.

My next experiment is to try Xtra system boards in a PG+. I am completely out of PG+ system boards, and need a test chassis....

[draganm]

Craig maybe your ideas of "crispy fried" is different from mine? If the tubes were really that burnt then the hawk would be purple instead of white.
MY 2 cents, since your doing this as a freebie, why make it harder on yourself than it needs to be. Install the Xtra as-is and the guy will be thrilled. Save the PG+ for someone else.

[CIR Engineering]

[CIR Engineering]

[Elaine Benes]

You can't run parts between the two chassis, period. They just don't interchange, they are more different than between Xtra's and XG's....

Leave the burned tubes in the Xtra and set up around them, you can EASILY make a very, very good picture with burned tubes, especially with an EM focus projector which will show absolutely no sign of the wear in terms of focus(it will still be very sharp).

The PG Plus is a VERY VERY good looking projector, and in my opinion, the absolute easiest NEC to setup WELL. It doesn't have any of the line distribution issues that virtually all later models had, the color is superb, focus and sharpness are above reproach. Don't discount the Plus just because its an older chassis, its a VERY good looking projector.

With NEC's the only thing that blocks getting a good looking picture is static image burn in, I've had ones with tubes almost burned black, and you could still get a good *looking* picture out of them.

Also, NEC's are the LEAST acceptable to swapping boards and parts between chassis of any projectors I've ever encountered. They are also the hardest to get back to "factory" type performance after they've been "messed" with. You can not swap the tubes from the Xtra to the PG Plus, even if you leave the magnetics in place, they use different tubes, the HV lead is even oriented 180 degrees from the Xtra to the Plus.

Technically, the Plus blue and red tubes will work in an Xtra, but they are not exactly the same and you can run into issues. I've used a PG Plus blue in an Xtra, but it was a hack solution which wasn't ideal, the HV lead was just barely long enough, and the connections for the upside down neckboard were also strained...

Seriously, set up the Plus and be amazed at how good they are, they're really an unsung hero among crt projectors. They perform REALLY well, and are a LOT quieter than any NEC after them too...

[CIR Engineering]

[Elaine Benes]

The PG Plus with perfect tubes is a MUCH MUCH better choice...set it up and see, it will only take 20 minutes if it hasn't been screwed with...

My first "lot" of projectors was three PG Plus's, they're really nice projectors...

[CIR Engineering]

[Elaine Benes]

Start reading on the NEC's there's lots to pick up...

There is a global width pot on the main Def board to tweak the width...

As with any crt projector, the way to run it easy is to do a VERY good mechanical alignment and setup, with NEC's the placement of the projector is of vital importance. They don't have continuously variable lens flapping, so you need to have the projector in the optimal position relative to the screen to get perfect optical focus. Also, for NEC's you *shouldn't* need point convergence. It is fairly easy to get the convergence pretty much perfect without using Point. But yes, you can easily add a point board, if/when you find one...The point boards from PG's and PG Plus's are interchangeable, but not with the Xtra's, they are, like with all things Xtra, unique...

Plus's generally run a LOT cooler than Xtra's or XG's, in my experience, which is likely why they make so much less noise, fewer small fans needed to keep things from burning up...The only concern heat wise in a PG Plus are the STK's on the convergence and focus boards, but they are heat sinked to the entire bottom of the chassis, so cooling is fairly good to begin with...

Don't use the internal test patterns to set up your NEC's, they work ok, but you'll notice the results from a test pattern from your source will be more accurate and last longer...

[CIR Engineering]

[benareeno]

set it up as per the manuals throw distance...it should run quite easily if you do. Premature tube burn is a possibility, but if the tubes are good, run the contrast low.

Also, don't forget...if you want to see even better colors from the NEC...defocus blue even more, it will make a big difference to the linearity of the greyscale.

[Elaine Benes]

Where exactly are these "width coils" you keep referring to ??

I'm pretty curious, as I can't for the life of me find them in my PG6100 out in the garage...

There is a HWidth adjustment pot on the Def board, you *can* use that to adjust the width wider than the factory set width, but you are inviting failure if you change a factory calibrated setting without knowing what effect it will have. Right ?

I'm not sure where all this "streaking" you've seen has come from either, I've owned 20 or more NEC's, PG's, PG Plus's, Xtra's, XG's every type, even a few 10PG's and I've never seen any hint of "streaking" except perhaps in one projector that had the reference mechanical white balance completely screwed.

There is a general recommendation handed out on forums about "maximizing raster usage" or some such pap, it may be great advice for a Barco*(its in their manuals in fact), or even good for a Marquee, but for an NEC, if you want to avoid trouble, and have an EXCELLENT image, follow the directions. That's all that is needed.

[macgyver655]

The system boards are definitely different. If you have questions on other boards I can look them up.

[macgyver655]

The width pot is on the deflection board. If you choose to adjust it I would recommend first turning off and unplugging the projector and rotating the pot back and forth to clean the wiper in the pot. Adjusting it when its dirty has been known to take out the output transistor.

[Mark_A_W]

There are no width coils on a NEC, that is a Barco thing.

I also have run a PG blue in an Xtra, it does work. But the G2 settings are quite different. I wouldn't do it if I could avoid it, and the plus chassis is almost as good (Paul thinks it's better).


With all PGs I would add a heatsink to the baseplate opposite the C and F drives, and some small fans to the deflection coil. Then they do not overheat.


The width pot should be set according to the procedure, 1.8v at PA Pin 2 to ground, with a video signal at 100% width.


There is a cap that needs changing on the def board from 47uf to 470uf, it is the big one front middle. NEC screwed up, the parts list says 470uf in the service manual, but they fitted 47uf. It needs a high ripple cap.



A PG Xtra/Plus is the best air coupled projector. Full stop. Not as noisy nor prone to streaking/raster visibility as an XG, as sharp as any other AC model, and colour filtered out of the box.


Oh, and basically none of the boards will swap.

[benareeno]

Thus my wanting to make a PGLC projector....but i need a workable chassis...hmmmm.

It would have the c-elements and lenses from a G70 which I can just sense wasn't meant to be...I feel a deep hatred toward that projector now. I would love a PG+LC...quiet and sharp, does 720p in a snap....adding the LC optics would be so freakin' sweet

[CIR Engineering]

[CIR Engineering]

[CIR Engineering]