CurtPalme.com Home Theater Forum

kschmit2 · Posted: Tue Jan 06, 2009 9:55 am Post subject:

MrKing (Conny Johannson) had an XG110 in with spot burn on blue in about 2004 or 2005. He eventually managed to track down the problem, but it took him about 1 year.

Tom.W · Joined: 09 Mar 2006 Posts: 6635

http://www.avsforum.com/avs-vb/showthread.php?t=900430 Crying or Very sad

Sorry but it brings back bad memory's ...

Chuchuf · Joined: 11 Mar 2006 Posts: 548

There are two causes I have found so far on the G90 that will allow the beam to collapse.
1. PA board failure that allows a voltage to drop which is part of the protect circuit (as MP indicated). So when the voltage goes away, the beam collapses but the protect circuit doesn't kick in because it looses it's voltage as well.
2. The second failure is on the YA board and happens after a period of time. This one I haven't fully figured out, believe it is an isolated incident and heat related?

Terry

stefuel · Posted: Wed Jan 07, 2009 1:47 am Post subject:

I love my AmPro, my AmPro loves me.
I've got no spot burn on my crt Mr. Green

**AnalogRocks** · Posted: Wed Jan 07, 2009 2:07 am Post subject:

stefuel · Posted: Wed Jan 07, 2009 2:21 am Post subject:

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

I can tell you EXACTLY how to put a deflection burn on a Marquee tube.

Pull the G2 lead off the pin. Let the CRT float up to full blazing brightness. Turn it off.

Poof..instant burn guaranteed.

The tube in question was a green P16 in (prior to the mishap) brand new condition with absolutely perfect, snow white, pristine phosphor
and even the bell glass was water clear with no trace of browning.

Yes, I was not thrilled with myself. But I was new to these machines and didn't know enough to not be dangerous yet. All I had to do
was connect the G2 lead to pin 6 and it would have been fine...or yank the P14 filament plug for a graceful burn-free shutdown.

I didn't know that on that tube type, the G2 pin is no. 6 while on a Marquee tube it's pin 2. Once I learned I never again put a tube at risk.

CJ

**Curt Palme** · Posted: Wed Jan 07, 2009 3:01 pm Post subject:

True Chris, but I was specifically talking deflection burn. Letting the G2 grid float will spot burn any tube in any set. I've done the same thing... twice... on Marquees. Try to cause a deflection type burn on a MArquee. I don't think you can do it. Smile

RVonse · Joined: 09 Mar 2006 Posts: 3152

Last time I looked at the schematic of the EHT module of my Barco I was amazed at the rediculous amount of safety engineering meant to shut it down. It was like only a small part built to generate high voltage and most of it was shut down circuitry. And you better not try to undo any of the safety or that will shut it down.

There's so many reasons to shut it down it amazes me that it can even run. Laughing