15GP22 June Rebuild Results...

[Pete Deksnis]

Check the link for info.
http://home.att.net/~pldexnis/input/news.html

[zenithfan1]

Getting close!! Lets keep our fingers crossed!

[Steve D.]

Great effort. Kudos to Scotty, John Folsom, Pete Deksnis and all who participated. I agree with Mark, that each attempt just moves us closer to success.

-Steve D.

[Sandy G]

Wonder if they had this much trouble building th' damthings in th' 1st place ?!? (grin)

[Pete Deksnis]

Originally Posted by Steve D.

Great effort. Kudos to Scotty, John Folsom, Pete Deksnis and all who participated. I agree with Mark, that each attempt just moves us closer to success.

-Steve D.

And let me add Bob Galanter, whose deep working knowledge of micro-type spot-welding and stuff I can't conceive of adds so much to this effort. At one point, Bob's procedural modifications to a process were embraced and adopted by Scotty.

Good point Sandy G. Scotty suspects that we see so many extra welds on the necks of 15GP22's because of rework during initial manufacturing rather than from rebuilding later.

Here's a shot of Scotty and Bob with John's 15GP22 being prepared for baking and evacuation. You can see the ill-fated evacuation tube extending from the bottom of the 15GP22. On the right there's a 19VP22 being rebuilt; this is the second one Scotty has done, and it was a successful rebuild.

Pete

[wa2ise]

CRT rebuilding also goes on in the 3rd world.

Wonder how well those CRTs come out, with respect to purity and so on. See
http://www.flickr.com/photos/greenpeaceindia/page2/
for more really bad news e-waste handling...

[fredh]

Congratulations to all involved in this project. I'm looking forward to the day I can take my weak (but under vacuum) 15GP22 to Scotty.
Nothing beats experience and knowing to abort the process shows just how much of that experience Scotty has.

[eberts]

Originally Posted by wa2ise

CRT rebuilding also goes on in the 3rd world.

Wonder how well those CRTs come out, with respect to purity and so on. See
http://www.flickr.com/photos/greenpeaceindia/page2/
for more really bad news e-waste handling...

That photo was dated 2002, those are b&W monitor tubes, they are not rescreening them or removing the implosion protection banding before processing, stupid. They don't even bother washing the outside of the tube.
I doubt they still waste their time doing it, unless their reality is as desperate
as it looks.
It was less expensive to purchase pallets of surplus new tubes. Used to get new monochrome monitor tubes for 50 cents each in quantity.

Scotty should have sealed that stem into the neck a little hotter, and make sure it is annealed afterwards. About 400 degrees in a hotbox for 90 seconds.
Keep those wires away from the tipoff, he may want to put a ceramic Shawfrank cover over the tip off coil on his next try, keep the high temp away from that thin wafer.

Those 20mm getters may cause a problem with arcing if there really is 12KV volts applied to the focus anode, or those deflection plates.
Suggest mounting the getters further up into the tube.

[Pete Deksnis]

Originally Posted by eberts

...Those 20mm getters may cause a problem with arcing if there really is 12KV volts applied to the focus anode, or those deflection plates.

The focus voltage is only 3.5 kV; it's the convergence anode that runs 12 kV.

[Eric H]

Tantalizingly close!

I was wondering though if the stem broke while the tube was under vaccum and being pumped down could this have damaged the phosphor?

[ohohyodafarted]

We were lucky Eric! It was under vacuum but the break didnt leave enough air in fast enough to cause any damage to the phosphor plate. And then there is also the issue the there is the shadow mask in front of the phosphor plate protecting it to some extent. All in all we lucked out on that score. So that tube will have another chance to live again some day.

Now on to rebuilding guns, because the company that did rebuild 2 guns for John Folsom, is no longer able to help us on that score. So I am going to embark on that part of the project myself. I have some good ideas and some resources at my disposal that sould make the job quite possible. It will just take some time to gear up to a level of proificency that is consistently successful.

We also used Vacseal on the glass to metal ring seals. The Vacseal held up well in the oven during the evacuation cycle, and we feal that it may possibly work to seal the leaking crt's that have gone to air. We will not know for sure until we actually try it on a leaker tube. Mine may be the first candidate for that experiment as mine is a leaker.

[andy]

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[Pete Deksnis]

Originally Posted by eberts

Scotty should have sealed that stem into the neck a little hotter, and make sure it is annealed afterwards. About 400 degrees in a hotbox for 90 seconds.

In the first shot, Scotty had just successfully completed welding a new gun into a 19VP22. You can see it there in the annealing box just under his chin. His digital timer is just above his right thumb. Also in that image, the vertical lathe with a new gun in John's 15GP22 is being prepared for the welding process.

Of course, once the gas jets are burning and rotating around the neck, the extra neck glass falls away from the stem in only about three minutes, as shown in the second shot.