Westinghouse H840CK15

[benman94]

Question for the 15 inch gurus: does pin 13 of the CRT itself typically show signs of having had 10 kV or so on it? Or would you only expect to see marks on hole 13 of the socket?

The CRT has absolutely no signs of having had convergence voltage on pin 13. I mean none. But the corresponding hole in the socket is pretty chewed up...

Maybe the tube was replaced at some point.

[benman94]

The CRT is good:

• The heaters lit normally, and drew normal current
• The neck didn't get any warmer than a typical color CRT neck
• Neither Dave nor I saw ANY glow whatsoever
• There is no discoloration of the cathodes or grids
• Multiple passes with three different tesla coils revealed no gas
• Cutoff on all three guns responded normally, though the pot needed to be in a different position for each gun
• And finally, the Sencore showed emissions results very similar to the Beltron

Dave was fairly confident when he left that the tube would produce a good picture; so am I.

Now to get the chassis to Nick...

[Kevin Kuehn]

Now that the CRT is know to be good are you going to pony up some more cash, or was it an all sales final kind of deal

[benman94]

Originally Posted by Kevin Kuehn

Now that the CRT is know to be good are you going to pony up some more cash, or was it an all sales final kind of deal

Dwight and I have been in contact, and he's happy the tube is operational. The trade was pretty damn fair considering the missing parts on the Westy. If he wants to reveal the details, that's his prerogative. The deal is done.

[Kevin Kuehn]

Originally Posted by benman94

Dwight and I have been in contact, and he's happy the tube is operational. The trade was pretty damn fair considering the missing parts on the Westy. If he wants to reveal the details, that's his prerogative. The deal is done.

Of course I wasn't really too concerned, just being a smarty pants tonight.

[benman94]

Originally Posted by Kevin Kuehn

Of course I wasn't really too concerned, just being a smarty pants tonight.

No problemo; I have a difficult time recognizing sarcasm/jokes.

On another note, I feel incredibly stupid about the swirling pattern on tube. It is not a phosphor defect; it is a defect in the front glass of the tube. At my parents home, there are two ceiling sockets in the main room of the basement, each with a pair of 300 watt lightbulbs. The table that the chassis is on is sitting maybe a foot "behind" the ceiling fixture. The light from the lamp was coming in at such an angle so as to strike an aberration in the glass near top right of the screen and then reflect that onto the bottom left of the screen. When I held the log paper up to it earlier, I wasn't seeing the distortion of the pattern itself but rather the shadow and mistaking it for the distortion (my eyesight isn't so great).

TL;DR The phosphor is fine, the front of the tube has some bubbling that created the weird pattern. In a normally lit room there should be no problem.

[ohohyodafarted]

Congrats Ben! I would bet your assumption that the tube had been replaced at some point, is correct. The tube seems to test like NOS. And the fact that you found some carbonizing only on the socket at pin13, I think your assumption that this is a replacement crt is probably correct.

In addition, it is my belief that late production crt's from RCA were more likely to be free from leak defects as RCA got better at producing good leak free tubes.

When you get a chance to pull the tube, it will be interesting to see if it has been re-necked which would indicate a tube that was either rebuilt at RCA or failed QC and reworked during original production. I have seen a couple 15Gs that were obviously renecked/rebuilt/reworked by RCA. Although this is just conjecture, I think that after the original production run was over, RCA rebuilt duds to have a supply of 15Gs for RCA's replacement crt division. It is well known that replacement crt price lists showed the 15G to be available for quite a number of years.

[benman94]

Originally Posted by ohohyodafarted

Congrats Ben! I would bet your assumption that the tube had been replaced at some point, is correct. The tube seems to test like NOS. And the fact that you found some carbonizing only on the socket at pin13, I think your assumption that this is a replacement crt is probably correct.

In addition, it is my belief that late production crt's from RCA were more likely to be free from leak defects as RCA got better at producing good leak free tubes.

When you get a chance to pull the tube, it will be interesting to see if it has been re-necked which would indicate a tube that was either rebuilt at RCA or failed QC and reworked during original production. I have seen a couple 15Gs that were obviously renecked/rebuilt/reworked by RCA. Although this is just conjecture, I think that after the original production run was over, RCA rebuilt duds to have a supply of 15Gs for RCA's replacement crt division. It is well known that replacement crt price lists showed the 15G to be available for quite a number of years.

Thanks Bob, it feels good to know I don't need to hunt for a good CRT. Eventually I'll want to pick up a spare for the Westy, but I have time yet.

It's funny you mentioned re-necking: the tube has a very obvious, some might say ugly looking, neck weld. Dave noticed it immediately. Either a QC failure, or the grand father of all Coloramas.

I'm guessing a later rebuild; there are four very small (a triad or two) regions of messed up phosphors. There's also a long black human hair caught between the dot plate and the front of the tube, but that would have to be from the initial stages of manufacture, no? She ain't pretty, but a like-NOS tube is like hitting the lottery. I can live with the occasional dead dot.