CurtPalme.com Home Theater Forum

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

Hi,
I just finished building my new theater and went to start setting up the projector yesterday when I found out that the projector will no longer lock onto a signal. I tried sending the projector 1024x768 from my xbox360. This is a signal that I already have setup and converged from my last setup and the projector has never had any problems with it. Now the image is constantly scrolling up. Sometimes the pj says that it is an unregistered signal and sometimes will randomly call it the "768p" name that I gave it. Only once did it lock on and it did this without warning and only for two seconds. There is no error code. The rear most red LED on the deflection board is randomly flashing. The 360 works fine on my computer monitor and I tried two different, known to be good, breakout cables. Removing the black V sync cable from the projector causes the scrolling to slow down a little bit and be more steady. The only thing different this setup from my last is that I mounted the projector vertically with the image bounced off of a mirror which means that I had to reverse the three blue-red leads going to the deflection board. Prior to this the projector wouldn't lock onto a 720p signal after warming up but I feel that was different issue as 720p was really messed up, not just scrolling.

So, what can I do narrow down the problem? Is this a board that Curt can fix or should I start searching?

Thanks for all your help with this great hobby!

-Greg D.

Mark_A_W · Posted: Sat Oct 11, 2008 9:20 pm Post subject:

Sounds like the deflection board (actually the oscillation circuits on the deflection board).

Unless you can do component level repairs you'll need to replace it, or send it to Curt.

It could also be the System board, but I don't think so.

BTW, these things are about 15 years old now....they will start to fail more and more.

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

Thanks for the reply. Although I'm handy with a soldering iron, I'm not comfortable with component level repairs. I had a good feeling that repair or replace would be my two options. Just out of curiosity, would repairing/replacing this board also fix my 720p problems?

Curt: If you are reading this, is this a board that you are able to fix?

I'll start searching for a replacement immediately. I don't think deflection boards from the Xtra series will work but what about non + PGs or 6PGs?

Thanks again,
-Greg D.

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

Sorry for the double post I've decided that I'm going to try to replace all the capacitors that I think are related to the oscillation circuits. Are there any other specifications that I need to look at other than voltage and capacitance? Will any radial electrolytic capacitors work or do they need to have a low ESR like motherboards?

Thanks in advance!

-Greg D.

Tinman · Posted: Mon Oct 13, 2008 4:13 am Post subject:

HAH! Good luck!

Blindly replacing caps won't get you anywhere. Especially since V-sync is probably not the deflection oscillator. Usually the horizontal tears if the caps are bad.

And.... if you flipped the image and never flipped the cables UNDER the Def board for the C-drive, then you need the manual.
The NEC doesn't really like 720p. Run it at 1080i.

I'd try re-seating all the system cards first. Put a tiny bit of de-oxid on the socket pins to clean them.

And.... DID you twiddle ANY of the pots?

Marc

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

Brooklyn · Joined: 17 Sep 2007 Posts: 494 Location: Morgan Hill, CA

Sounds like a deflection board issue. 720p is fine I think, that is all I ran on my 6PG, it looked great. It seems the oscillator circuits on the deflection boards tend to go out, it happened to my 6pg too. You can try adjusting the 2 oscillator pots on the top right of the deflection board. I don't think it helped though when my deflection board went out.

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

Thanks for all the replies.

I'm pretty certain from reading other threads that it is a deflection board issue. Plus I have the V Fail LED blinking. I'll try cleaning and re-seating all the connectors as well as very carefully touching the oscillator pots. I'll mark those so that I can get them back to exactly their starting position if they don't do anything. Aside from the focus pots, I have never touched any other pots inside. I no longer have my oscilloscope and wouldn't know what to do with it if I did mess up some pot.

As for 720p, I feel that it is a very different problem most likely on the system board. I just want it to sync to the same 1024x768 that it always has.

I won't be going in completely blind. From my reading on here I have a good idea of which capacitors deal with the oscillation circuits. I'm in college so I have no money but I do have friends who are EE majors and should have access to a capacitor tester. Since I have the problem narrowed down to a single board I can just test/replace until it is fixed.

Brooklyn: What were your symptoms when your oscillator circuits failed?

Thanks for all the replies!

-Greg

Brooklyn · Joined: 17 Sep 2007 Posts: 494 Location: Morgan Hill, CA

The projector started dropping the signal, until it would not sync entirely. I believe it was the unregistered signal error, although this was a year ago I don't exactly remember. You might be surprised that a working deflection board will fix both of the problems.

Tinman · Posted: Mon Oct 13, 2008 5:02 pm Post subject:

Greg,

If you can borrow an ESR meter, check all the little caps around the oscillator IC. They will be small value, and often you can even see the leads and solder corroding. It's usually 2 or 3 caps that go, so don't just go replacing things blindly. DO NOT adjust the 2 oscillator pots! There is a procedure for that. The oscillators DO NOT affect the Vertical hold. If you have horizontal lock, they are fine.

I think you are loosing sync somewhere else, or try sync polarity.

Marc

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

Thanks for all your impute

I won't mess with those pots. I didn't really like the idea to begin with. I'm almost 100% sure that the EE lab on campus has an ESR meter that I can use. I'm glad that those meters can be used with the caps still on the board as that will save me a huge amount of time. Thanks again!

-Greg

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

IT'S ALIVE!!!

I wasn't able to borrow an ESR meter or find a cheap replacement so I just replaced all the caps that I thought had to do with the oscillation circuits which were about 13 of them. I replaced all of them at once so I'm not sure which one or two caused the problem.

This surprisingly fixed both of my problems. The projector now locks onto my known good 1024x768 signal without any vertical scrolling. It also fixed my issue where 720p and 1280x960 would get completely mixed up and sheared. 720p is now displaying properly although not converged because I haven't set it up yet.

Thanks again for all the great help on this forum!

-Greg