CurtPalme.com Home Theater Forum

tye3333 · Joined: 20 Oct 2012 Posts: 19

Hi everyone
I don't often post here because I don't often play around with CRT projectors. I know my way around arcade monitor/chassis but projectors are another thing!

So I picked up a working NEC PG-9200G (maybe the EXRA type?) and it was working fine for me for about a runtime of 8-10 hours total, and the total unit time is at 500hour.

Thinking I was all safe I went to the trouble of mounting it to my roof and started to converge my new 5m screen when it happen. my blue tube went a solid colour then turned off. Thumbs Down

so what I have now when I turn the unit on is red and green tubes run fine as they should, no problems there. but the blue is full bright blue with raster lines across the screen. I have tried unplugging the screen input (G2) and tube dose not come on (dur) and tried unplugging the 10 pin input lines (G1, H1 ect.) and again nothing on screen. I have tried swapping the green and blue 10 pin input lines and I get the same blue screen (I can not plug green into blue because it wont reach). the neck board is the larger type for these units that has a VPA13 driver chip onboard (PWC-3958).
Also the 7-seg display on the back comes up with "Fd".

Please, any help of info on this unit will be so good, I have been working on this thing now for hours, upside down, not wanting to take it back down and am in need of help

Thanks heaps
Tye

**Curt Palme** · Posted: Tue Oct 06, 2015 1:51 pm Post subject:

Try tapping on the neck of the tube to see if it cuts in and out. They do short out sometimes. I should have a decent blue tube for cheap if you want it.

The Fd comes up because the HV is shutting down to protect the set.

I'm out of town for the next 10 days, but email me at curtpalme at shaw.ca if you want the tube.\

The video driver circuit driving the blue CRT socket/video amp is usually OK, but it is possible that it has an issue as well. MOre likely to be the tube though.

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

I once had the exact same problem with the blue tube and it was the neckboard, there are a few topics on this forum regarding bad blue neckboards in PG xtra. The other colors oddly do not fail.

tye3333 · Joined: 20 Oct 2012 Posts: 19

Thanks for the quick reply! So this morning I dug out my rejuvenator (sencore CR7000) and tested my blue tube and found no shorts on the tube at all, so I guess that's good news. I just now I'll be looking at the neck board but it's good to know I'm not the only one with this problem

tye3333 · Joined: 20 Oct 2012 Posts: 19

Just done a search on the forum for bad blue neck boards and couldn't find anything, could you point me too them so I can do a bit of reading?
Thanks

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

Oh well, I could only find one "want to buy" topic on the blue neckboard, but I pretty sure somewhere it was said out loud that the blue neckboard was somewhat problematic on the PG xtra. I had thousands hours od experience on PG xtras and only got one blue neckboardfailing though.
Anyway it most likely it has a bad VPA13 and a random diode shorted out, from this the VPA13 is harder to tame, and in fact is cheaper to buy a complete board than hunting for the IC.

gregstv · Joined: 27 Aug 2007 Posts: 628 Location: Australia

Just buy a tube and a neck board from Curt. I don't think Curt would be asking to much for them. Shipping maybe the only concern.

tye3333 · Joined: 20 Oct 2012 Posts: 19

Ok so after a little bit of work things have changed up a little. I removed the neck board, done some testing and found a surface mount diode bad on the back. I replaced the diode and the tube come up, all good! YES! ....but the joy only lasted 2min before the tube started flickering and turned off, it occasionally flicks back on and off again. So now it seems the only difference I have now is I have screen control back but other then that, nothing. I was able to swap the green and blue outputs from the video board and blue signal works fine on the green tube.

So I was able to find a VPA13 chip ($55USD thanks very much) and I am hoping this will fix the problem as I cant find any other problems on the neck board.

But my new problem that i have just seen today is a have a burn hole in the center of my green tube, I know there is only one solution to this problems sadly but I'm more interested to find out how this happened, i don't think it was anything i have done when testing for problems but i don't know, any info on this?

Last thing, dose anyone have a manual/schematics for the PG xtras ?

tye3333 · Joined: 20 Oct 2012 Posts: 19

This is a photo of my green tube burn hole

https://www.dropbox.com/s/gsv9ql40oc3j8mt/IMG_3859.JPG?dl=0

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

You most likely did the spot burn when you left your machine running without G2 lead... Confused

I am also pretty sure Curt would sell a complete neckboard for way less than $55 Confused

tye3333 · Joined: 20 Oct 2012 Posts: 19

oh double poo!, I guess now im after a green tube and blue neck board

**Curt Palme** · Posted: Wed Oct 07, 2015 3:20 pm Post subject:

Yeah, a lack of G2 wire will do this, bad design on NEC's part. I replied to your email today. I have both a mint set of PGXtra tubes as well as some lightly worn greens, but I'm out of town for 10 days. Will email again as soon as I am back, a week THursday.

tye3333 · Joined: 20 Oct 2012 Posts: 19

Big thanks to everyone who helped with my problem, I got my new VAP13 chip and that seem to have fixed the problem, Inpwnhave control over my blue tube again. My next problem is that I started working on my projector before I looked at this forum and I played around with the trimpots that everyone says not to touch- Big oops!
This is a photo of my screen settings, the blue circled only got moved a little, and I think are back to where they started from but the red circled is way off, and I don't know where it started from
https://www.dropbox.com/s/9lzt4c9aum869nq/File%2015-10-2015%2C%209%2052%2036%20AM.jpeg?dl=0
Same again with this next photo, the blue circled I only just turned a tiny bit, the put back. But the red circled I don't know where is started from.
https://www.dropbox.com/s/i9quypum5kbzrol/File%2015-10-2015%2C%209%2052%2055%20AM.jpeg?dl=0

I know I should not have touched these and if I had read the forum frist I would have never gone near them
If anyone can help with these adjustments or how I should go about recalibrate them I would be greatly appreciated.

Thanks again
Tye

**Curt Palme** · Posted: Wed Oct 14, 2015 11:31 pm Post subject:

Not sure if I posted earlier in this thread, but long ago I spent a VERY frustrating week trying to figure out how to calibrate those controls on a plain PG set. I got help from the NEC expert (now deceased), Doug Baisey, who knew NECs inside and out. He told me 'Oh, you're trying to figure out the NEC white balance? Great, let me know when you figure it out, I never could!'

So that tells you that no one has ever figured it out. The Japanese to English instructions in the service manual are TERRIBLE, so the only advice I can give is:

If it is only one control that you misadjusted, if you say the second one is close to where it was, then I'd run the set at low and high brightness with a stepped gray scale test pattern on the screen, to see if you can get it close. The video boards and neck boards all work together, with feedback loops between them, which is why I couldn't just send you a replacement board out of another set, as they are all calibrated when in the set, and each video board control setting is slightly different from the next one.

Bad news, I'm sorry, but it's the truth.

Hopefully you can find a setting of the control that is close enough, then work with the color balance controls within the menu to fine tune to an acceptable picture.

**Curt Palme** · Posted: Wed Oct 14, 2015 11:32 pm Post subject:

BTW, I am back in town now, and am working through the 300+ emails I have.

If you still need a tube(s), and if you emailed me, I'll respond by the end of Friday.