CurtPalme.com Home Theater Forum

Zebu Fellenz · Joined: 21 Dec 2006 Posts: 2567

comm · Joined: 09 Mar 2006 Posts: 46

Haha. Guess those lines do kind of look like some of the creative drawing exercises I have done it art classes.

Any suggestions on how to get the BurnBeast out of the my projector? The burn happens when the projector is turned on not off. I am pretty sure one set of those lines was the first time I powered on, and one the second. The raster was lit up, but no more than the red tube. The green tube raster was not lit up at all compared to the red and blue. The other two tubes do not have this burn issue at all. I had to put a new scan yoke on the blue tube because the old one was trashed by glycol.

Thanks again.

David

comm · Joined: 09 Mar 2006 Posts: 46

Hey guys,

I haven't had much of a chance to work on the 9500 for a while. I really want to get this thing going so I get get it off the living room floor. Any ideas on where to start? Could contamination in the tube cause this or is it more likely a board in the projector? Since the burn is not just horizontal or vertical can I eliminate the hor. and vert. boards? Since it is on startup it wouldnt be the spot burn protection would it? VIM possible?

Thanks for any help

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I hate to say it but it looks like you'll have to turn it on again and hope for the best. what tube is it on? If it was some sort of scan failure then it would happen to all the tubes unless it was a bad scan yoke on the tube affected. It could be the neckboard, if its only on that tube. You may have doen the mod right but the spotkill circuit on that neck board might have been ready to go anyhow. Too bad yo dont have any old tube you dont care about and hook it up and turn it on and see if it repeats, first using one of the other neck card then using the one on the spotburned tube. you wouldnt have to remove your old tube either.

Athanasios

stefuel · Posted: Fri Jul 11, 2008 10:14 am Post subject:

That's a odd one for sure. Whatever it is, it appears to have done it 4 times. I've never seen spot burn occure anywhere but the center of the raster. That's not centered. Is there any chance that a pin hole of sun light has come in through the lens and etched the tube? Is it only on one tube?

comm · Joined: 09 Mar 2006 Posts: 46

Sorry if I haven't been clear, I have turned it on twice. Each time it burned a pair of the lines. Yeah it would be a lot easier if I had a spare tube, if I could find one cheap I might pick one up. It is the blue tube and the scan yoke has been replaced. The old one was trashed by the glycol leak. Is it possible that the new scan yoke could be causing this?

Thanks again

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Yepp i guaranty thats it, those scan yokes are very delicate, one scratch or nick to the windings and that yoke is shot. i still test it on a used spent tube, if it doesnt happen to that tube then you know its the scan yoke that did the damage. Then to be 100% sure swap the scan yoke from your tube to the used spent tube and see if it repeats .

Athanasios

comm · Joined: 09 Mar 2006 Posts: 46

Thanks for the help Athanasios! I hope it is just the scan yoke, a lot easier fix than some of the alternatives.

Out of curiosity, anyone seen bad yokes make burns like this before?

Fujifrontier · Joined: 20 Oct 2007 Posts: 354 Location: San Antonio, Texas

how visible is the burn whe nyou turn the thing on?

comm · Joined: 09 Mar 2006 Posts: 46

It's fairly visible, though I have not put a lens on it to see what it looks like on a screen. I can definitely see it without looking too close. That's how I first noticed it, I thought I had a string of silicon on the lens. Wish my first guess was right.

David

comm · Joined: 09 Mar 2006 Posts: 46

Made some progress on the 9500 finally. I talked to Curt and he thought that it could be contamination in the tube. I pulled the tube to put it face down so I could tap on the neck. While I had it out I noticed that on of the ground straps was really close to the terminal block on the yoke. I pulled it away some with a zip tie. While I was at it I also pulled the ACON and contrast mod board. This time when I turned it on it didn't burn the tube like it did the previous two times!

Pulled the G2 down to 30 or so on the blue and the raster now looks like it should. I put a lens on it to see what the burn looks like. I attached a picture of it, looks pretty distracting... I also noticed what looks like some vertical burn from the center of the raster to the bottom edge.

While I was working on it it noticed the sound of HV crackle coming from the blue tube. I think there is some sort of leak from the ground strap. I did have to make a new one due the the glycol leak. I used 3m 1181 for the copper strap:

http://products3.3m.com/catalog/us/en001/electronics_mfg/electronic_handling/node_GSZ0WDCLQ8gs/root_GST1T4S9TCgv/vroot_8088DWF29Kge/bgel_2H2H9B33G0bl/gvel_RQ89J1RQDXgl/theme_us_ehpd_3_0/command_AbcPageHandler/output_html

And something like this to cover the copper:

http://solutions.3m.com/wps/portal/3M/en_WW/electronics/home/productsandservices/products/TapesAdhesives/AntiStaticTape/

Not sure how the HV is getting out. I haven't checked the strap yet.

So my guess is that the HV leak caused the spot burn somehow? Either by traveling down the outside of the ground cable jumping the the terminals on the yoke or by some sort of induction by having it to close to the terminals?? Or maybe I just dislodged some contamination by tapping it? I don't think it was the either of the boards I pulled.

Since I am pretty sure now it is either the tube or the grounding I am really tempted just to buy a whole new Marquee tube assembly, since this one is probably trashed anyway. Anyone have any sources on these besides VDC? Almost wish I would have picked up one of the ones on the bay recently just to get this up and going.

Thanks for the help everyone!

David

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Yepp its Shot!!! Were the grounding straps you used insulated? I bet they shorted the convergence yokes causing they squiggly burn.

your in luck check this out:
https://www.curtpalme.com/forum_archived/viewtopic.php@t=11628.html

Athanasios

comm · Joined: 09 Mar 2006 Posts: 46

Yeah, the grounding strap was insulated. The leads from the strap to the neck board were the ones I pulled from the original setup, so I would think those should be fine. It would have to be the new copper tape I put in or the tape to insulate it.

David

Chuchuf · Joined: 11 Mar 2006 Posts: 548

David,

Just caught this thread.

Grounding the outside of the tube with tape can be done a variety of ways. It can be done with copper tape or lead tape. All you are trying to do is to ground the aqua dag so that there isn't as much crackling from the HV.

Looking at the burn you have on that blue tube (if that is really what it is), I would try and run the tube (once you have figured out what is causing the burn) as the B tube gets defocused a bit and it doesn't look to me as though the burn is that dramatic.

Put up an all white field projected on a screen and see (after defocusing B a bit) if you can see the pattern on the screen.

Terry