CurtPalme.com Home Theater Forum

[listenlounge]

Hi peoples
As mentioned. I bought a NOS 9500LC Ultra Chassis from Curt earlier this year. ( The one where the new tubes were BROKEN in transit ( Sad Face Sad Face ). I put my 180DMB's ( new set ) into it and my HD145's on the front. Nice little zero hour set.

Watched the new Bourne Movie last Saturday and once it was finished - Boom - Blue as far as the eye can see, can still see the pic, but like it is overdriven. Blue enough to look like a BSOD on a windows computer.

Havent touched anything yet, except to try switching inputs from the Moome back to another input, removed all signal cables, checked G2 levels, drives and sub-brites and it all looks solid.

Any thoughts?

I've got a movie marathon planned this weekend......

Thank You

[barclay66]

[listenlounge]

Thanks mate
I haven't pulled out any of my meters yet to test the voltage. I did try to adjust the G2 just now and regardless of what the setting was, the brightness remained constant.

I have a spare set of neck boards, and a spare set of tubes, and a spare HVPS. I will do as you say and test them in order.

Appreciate your help, very informative.

Ben

[Curt Palme]

Barclay has it correct. A super bright blue tube isn't dangerous to the tube (or you), unless you power down... possibily. What I would do at this point is look into the blue tube to make sure you don't have a spot burn in the middle of the tube face. IF not.... good!

Leave the blue neck board connected, but pull iit off the tube neck. Measure the G2 voltage that should be somewhere between 300-600 volts or so. If it's higher then your HVPS or G2 control circuits may be bad), or you may have had what's called the G2 'snap" (I think that's what Tim calls it'), where the CLM glitches and sets the G2 setting to 100. If you have no G2 voltage on the white wire, then trace back to the G2 pin to see if you have G2 voltage coming from the HVPS.

I've had solder joints and resistors crack on the neck board, causing an open circuit right by the G2 pin.

Worst case, you have a shorted tube, but MArquee tubes don't typically do that.

[Curt Palme]

Barclay has it correct. A super bright blue tube isn't dangerous to the tube (or you), unless you power down... possibily. What I would do at this point is look into the blue tube to make sure you don't have a spot burn in the middle of the tube face. IF not.... good!

Leave the blue neck board connected, but pull iit off the tube neck. Measure the G2 voltage that should be somewhere between 300-600 volts or so. If it's higher then your HVPS or G2 control circuits may be bad), or you may have had what's called the G2 'snap" (I think that's what Tim calls it'), where the CLM glitches and sets the G2 setting to 100. If you have no G2 voltage on the white wire, then trace back to the G2 pin to see if you have G2 voltage coming from the HVPS.

I've had solder joints and resistors crack on the neck board, causing an open circuit right by the G2 pin.

Worst case, you have a shorted tube, but MArquee tubes don't typically do that.

[cmjohnson]

Is the white flying lead on the neck board even properly connected to pin 2? Caution, that wire carries up to about 600 volts
so be sure not to touch the open electrical contact at the end of it!

If it's a G2 problem, then you should see brighter diagonal lines on the face of the tube, brighter than the rest of the raster.


Shutting down a Marquee in this condition will almost always result in a spot burned tube.

The way to save the tube in this condition is to pull off the P14 filament voltage supply plug off the motherboard. It is
located very close to the neck card cage, underneath it, under the blue tube.

The safest way to do this is to pull off the side cover and the metal shield under the side cover and then you can easily
and safely reach the P14 plug.

Pull the plug and wait until all traces of image are gone from the CRT face. Then power down the unit and then reconnect
the P14 plug. Then look for the possibility that the G2 lead may simply have come off its pin. Which is pin 2 if your tubes
are P19LCPs. Pin 2 is the clockwise pin in the two pins that are in their own compartment on the tube base.

I HAVE seen Marquee neck cards fail in such a way that G2 failed to function properly. Which is absolutely bizarre as the entire
G2 circuit on the neck card is literally three resistors and one capacitor. I have a couple of those cards in the "Some day I will
try to fix that problem" pile.

[listenlounge]

Thank you for the help
It is not the neck board. I switched out a neck board for a spare i had here. No difference.
Curt - yep, diagonal lines.
Spot burn, not yet, but when it powers down I see the beam current centre out as the sweeps die and i reckon if i keep doing it i'll screw the tube. I do have a brand new set of tubes, not that that is an excuse to toast one "for fun"

What I want to do next is test for g2 voltage at the connector to the neck board and the white wire to the tube.

My plan of attack is

1. Pull out the HVPS and check the contacts and seating in the connector for proper mating.
2. Put back said HVPS.
3. Pull the HV lead to the blue tube, insulate the open socket on the HV splitter to prevent arcing to ground and power the step up - i.e. without HV to the blue tube.
4. Meter the voltage coming into and out of the neck board.

Sound reasonable?

Another step? A better way?

I also have a spare HVPS here if needed. Matter of fact, I've got a spare everything.

Do you guys remember "Short Circuit" where Number 5 built an entire replica robot of himself from spare parts? And then sent it in to be blown up?

Love that movie. Steve Gutenberg. Ally Sheedy.

Cheers all

Ben

[barclay66]

Hi,

Swapping the HVPS with the spare one should be enough for the moment. You only need to do the other things if You're planning to repair the HVPS...

Regards,
barclay66