CurtPalme.com Home Theater Forum

**Curt Palme** · Posted: Sun May 23, 2010 5:19 pm Post subject: (almost) infinite tube life?

I post once in a while about my retro BG808s with the PT 18 tubes. It's time again. Smile

Ever since I got the set, it's had a bit of blue haze, so anything over 50 contrast had halos around it. I fixed that by running a 45 contrast. Wink

(what's the saying about a plumber and his toilet...?)

So the various g/fs with kids ran the crap out of the set over the last 5 years that I've had it, so I turned it on after Sparky moved out, and was horrified to see that the blue now had massive haze at any contrast. So this morning I pulled the tube.

I will add that this set has 45,000 hours on it or so (I'll post a pix in a bit), so I always assumed that the set had been retubed a few times. White balance (save for the blue haze) was still good, but now the haze was unacceptable.

I've seen LC tubes develop fungus and turn yellow, but I don't think I've had a tube's glycol go milky. It was TERRIBLE! There was a thin film of haze on the tube face itself as well as on the back of the LC housing, but a careful cleaning got rid of that, and I'm now reassembling the set. As I was pulling the tube out, I noticed the date code on the tube, 1997, which is the same as when the set was made. So I'm pretty sure that these tubes are original.

The tube face was maybe an 8 to 8.5 on the blue, the slightest yellowing of the phosphor, and while I'm not pulling the green tube, I'd expect it to be the same, maybe 1 step lower.

So to me that's pretty amazing, an RP set, 72" with 45,000 hours on the original tubes.

I'm about to do a 'from scratch' setup, including astig and focus. I'll post a pix once I'm done.

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

I'm amazed that they even still have good emission.

Running reasonable contrast settings sure does help tube life, doesn't it?

Also, in an RPTV format, PT18s or any other of the usual FP type projection tubes end up working with a very SMALL screen relative
to the screen size of most any FP setup. This means you really don't have to drive the tubes hard at all to get more than adequate
brightness. They're running on maybe half the screen area of an FP setup, with accompanying low contrast settings to match.

CJ

**Curt Palme** · Posted: Sun May 23, 2010 5:49 pm Post subject:

Just did an astig tweaking and touched up the focus. WOW! Never looked this good, I fell back in love with the 350lb beast. Wink

Might need to watch TV on it tonight for a change. Next weekend: 5.1 into the upstairs 'family' room.

Got your PM, rest of the stuff leaving Tuesday.

**Curt Palme** · Posted: Sun May 23, 2010 6:05 pm Post subject:

Set pictures..

stefuel · Posted: Sun May 23, 2010 7:57 pm Post subject:

"so I turned it on after Sparky moved out"

So you scared another one away? Just to big for her eh.
Game on!!!

**Curt Palme** · Posted: Sun May 23, 2010 7:59 pm Post subject:

That was a couple of months ago, catch up! Smile

stefuel · Posted: Sun May 23, 2010 10:49 pm Post subject:

**AnalogRocks** · Posted: Mon May 24, 2010 7:43 am Post subject:

I want one of these sets and somewhere to put it Very Happy

Kiev Savoie · Joined: 25 Oct 2007 Posts: 432

This makes me feel really good about my RP setup with the G70. My contrast stays at 40. I could probably pull out a little more black detail by bringing it up but i have resisted the temptation. It's nice to be able to watch whatever on it and not be worried about wasting my tubes on Two and a Half Men or whatnot. I must admit though, it does not take the place of a large screen FP setup, next project... Very Happy

**Curt Palme** · Posted: Mon May 24, 2010 11:04 pm Post subject: