CurtPalme.com Home Theater Forum

SweetChuck · Posted: Sun Dec 20, 2009 8:32 am Post subject: Pop goes the marquee :(

Long long after powerup, watching a movie I hear a loud crack like arcing only louder, the Pix dies for a second or two and comes back up. Only now I have no EM focus. I checked the focus board and all looks superficially good and no bad smells etc. Does anyone know of common faults with the board? or maybe it was an arc that took it out. I've also got a leaking bellow on the blue so looks like I need new ones. What a crappy day I'm having 1 hour after my projector dies I broke a tooth Evil or Very Mad

What next???

Thanks all

cinema mad · Joined: 25 Nov 2009 Posts: 219

It was prob the Leaking Glycol from the Bellows that corsed A short somewhere..

Is the Projector ceiling mounted or floor mounted ?..

Cheers...

CIR Engineering · Posted: Sun Dec 20, 2009 4:01 pm Post subject: Re: Pop goes the marquee :(

mp20748 · Posted: Sun Dec 20, 2009 4:08 pm Post subject:

Check your HVPS and see if it's a 34.9KV

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

yeah like someone said if it's on the floor and leaking that could certainly cause an arc/short. Order the bellows from Nash and follow this guide

http://www.curtpalme.com/forum/viewtopic.php?p=189967#189967

I can also do it if you don't want to deal with it. Biggest concern is first removing the tubes and finding the leak, hopefully it didn't drain back into the chassis.

**Curt Palme** · Posted: Sun Dec 20, 2009 8:00 pm Post subject:

If the arc was loud, then I'd suspect nothing else other than an HV arc that could have taken out the HDM (most likely), or the V board.

Disconnect/unplug the C board ribbon cable and hte focus board and see if the set comes back to life.

SweetChuck · Posted: Sun Dec 20, 2009 10:30 pm Post subject:

Thanks for the replies. You know is does almost look like low HT symptoms as the EM focus sort of looks like its trying to work. When I adjust the centre focus you can get the edges fine bit centre bad and vice versus. The PJ is cieling mounted so I don't think Glycol got on any boards but possibly it got around the blue HT plug. This set has had a history of arcing but this was due to a bad HV splitter. What a good point to measure the HV? I've never done a 9500 before .

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

You symptoms for the focus sounds like the mosfett's went on one or all channels. there are 9, 3 for each channel that switch different capacitors in and out for different frequencies. you could test to see what internal frequencies focus normal. also do one color at a time . hit color the color you want to test the focus of, ramp it up and down and see what it does for each color . you might only have one bad channel or all three.

change the internal frequencies and test one by one, some may focus while others won't( like the closest on to what your using now)

Athanasios

SweetChuck · Posted: Sun Dec 20, 2009 10:48 pm Post subject:

I see the Mosfets, 9 of them next to various caps I'll see if I can test them out of the unit as I have it all in pieces. You know I had a thought that it couldn't be low HV related or the Pix would grow bigger but the raster stayed the same size.

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

you should also test the smaller mosfets that are the drivers, they are near the bottom of the board, Q1,Q3,and Q5 and all the parts near them, they turn on the larger mosfets after getting a band switch signal from the CLM. or it could be the Focus wave form generator on the CLM that is not working but i put my money on the focus board, it might be easier to just look for a new board. I still have not fixed mine 100% I can not get the one mosfett for each channel to turn on. Might be the zener diodes near them.

Athanasios

mp20748 · Posted: Sun Dec 20, 2009 11:33 pm Post subject:

Check and make sure you have a 34.9kv HVPS. Arching to the degree of muting the image was a problem on the earlier 34.0kv HVPS and was rare on an 34.9kv HVPS.

That arching can take out a fet on the HDM or transistor on the VIM. And almost any of the other boards, but the VIM and HDM is the most common.

If you're getting a lot of arching with a 34.9kv HVPS, you have a serious problem that could eventually damage other boards, and that may explain why you lost static focus (rare to me).

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

Actually i think he lost Dynamic. if you can get the center good and then loose center and get edges its the dynamic, those are the 9 fets that switch in and out the film capacitors for different band switched resolutions.

Athanasios

mp20748 · Posted: Sun Dec 20, 2009 11:41 pm Post subject:

Yep, arching is tough on FETs. especially the 2N7000

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

SweetChuck · Posted: Sun Dec 20, 2009 11:54 pm Post subject:

Thats correct I've only lost Dynamic. You know I have a feeling its not the Focus card, I just measured every forward junction of every Semiconductor on that board. Unfortunatly I won't be able to get to rest of the projector for another 10 hours as I'm Working today and have to go to the God damn blood sucking dentist today .

I'll pick this up later and get some more fact as I'm just stabbing in the dark ATM.

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

Those you need to test out of the board, they look ok while in.

Athanasios

**Curt Palme** · Posted: Mon Dec 21, 2009 1:20 am Post subject:

I've got a messload of spare focus boards. Might be cheaper to buy another one off me rather than repairing that one..

SweetChuck · Posted: Mon Dec 21, 2009 1:33 am Post subject:

**Curt Palme** · Posted: Mon Dec 21, 2009 2:23 am Post subject:

Email me at curtpalme@shaw.ca and I'll give you a couple of options.

SweetChuck · Posted: Mon Dec 21, 2009 9:32 am Post subject: