View Full Version : Westinghouse H840CK15


benman94
10-06-2017, 10:56 PM
I picked up the Westinghouse today from Dwight here in the Metro-Detroit area. My father went with me, and after going out for a late dinner, we decided we weren't going to try to carry the chassis plus 15GP22 up to my walk-up apartment.

Since I have sold off most of the items that my parents were very graciously allowing me to keep in their unused basement, we decided to take it out to their house near Flint to stay temporarily. He called my mother, explained the situation, and she begrudgingly allowed the Westy in the house. Thanks Ma! :o

We set both chassis on a table in the main room and moved the cabinet back deeper into storage.

We turned immediately to testing the 15GP22, and were pleased with some slightly encouraging signs. The heaters lit normally using my regulated 6.3 volt supply, and drew normal current. It passed a date with my tesla-coil, and I put it on the Beltron using hastily made clip leads. To our surprise, the tube shows excellent emissions on all three guns, with the red looking the strongest, and the blue looking slightly weaker than the green (and taking a tad longer to "wake up").

Neither he nor I saw any pink or purple glow between any elements in the gun like I have when testing other gassy 15GP22s.

The meter was not pegged on any gun, but we still haven't tested cutoff (the Beltron can not do this). Like the idiot I am, I left my Sencore at the museum by mistake, so I will have to wait for further testing in November when I get back from Ohio. I think the Sencore will be a bit more conclusive. If I find I can get the meter to peg on the Sencore with certain settings of cutoff, then it is clear the tube is gassy. If cutoff responds normally, then the tube is quite possibly good.)

Tonight was by no means conclusive, and I'm going to continue to assume the tube is a dud. That said, I may get a pleasant surprise when I get the tube on the Sencore, and eventually (God willing) a working 15 inch chassis.

Thank you again Dwight! :thmbsp:

benman94
10-07-2017, 09:57 AM
I've determined how Dwight got the low readings for emissions by replicating them; he accidentally connected the G1 lead from the B&K to G2, not G1.

Some photos of the chassis and jug:

https://thumb.ibb.co/hkYXVb/20171006_223725.jpg (https://ibb.co/hkYXVb) https://thumb.ibb.co/mQxRqb/20171006_223744.jpg (https://ibb.co/mQxRqb) https://thumb.ibb.co/mAJo3w/20171006_223801.jpg (https://ibb.co/mAJo3w) https://thumb.ibb.co/bBmaiw/20171006_223808.jpg (https://ibb.co/bBmaiw) https://thumb.ibb.co/hbOcwG/20171006_234108.jpg (https://ibb.co/hbOcwG)

benman94
10-07-2017, 10:29 AM
Any ideas on what causes that weird swirling pattern on some color CRTs? I had a 21CYP22 with the same damn thing. It didn't seem to alter the picture in use, but it looked like hell when the set was off.

Perhaps RCA continued their prewar policy of selling "lesser" CRTs to competitors and holding the best for their own sets.

The 15GP22 in this set was built in the 13th week of '54.

benman94
10-07-2017, 12:33 PM
The getter above the blue gun looks a bit odd to me, almost like a small portion of the center has flaked away from the glass. It isn't white though, everything is still a dark grey/black color:

https://thumb.ibb.co/cg3V0b/20171007_121913.jpg (https://ibb.co/cg3V0b) https://thumb.ibb.co/e3216G/20171007_121803.jpg (https://ibb.co/e3216G) https://thumb.ibb.co/j8u9tw/20171007_121807.jpg (https://ibb.co/j8u9tw)

The other two getters look fine, and actually a deal bigger than the getters on the tube in the CT-100 I sold:

https://thumb.ibb.co/fpx7fb/20171007_121840.jpg (https://ibb.co/fpx7fb) https://thumb.ibb.co/hsdDLb/20171007_121849.jpg (https://ibb.co/hsdDLb)

jr_tech
10-07-2017, 03:49 PM
Impressive! that chassis is a beast! Is the circuitry much different from the CT100, or did Westinghouse not get innovative?

I assume the chassis is copper, like my h22t155, or is that rust?

I have seen drying patterns in some early kasil settled phosphor tubes, but not rings like that... could that be a moire pattern perhaps generated by poor contact of the silk screen during the screening of one of the phosphor colors? Seems likely that RCA would sell less than perfect tubes to competitors.

Perhaps the getter above the blue gun was the first one flashed after "pinch off", in a fairly poor vacuum. :scratch2:

Looks like a very fun project.

jr

benman94
10-07-2017, 04:16 PM
Impressive! that chassis is a beast! Is the circuitry much different from the CT100, or did Westinghouse not get innovative?

I assume the chassis is copper, like my h22t155, or is that rust?

I have seen drying patterns in some early kasil settled phosphor tubes, but not rings like that... could that be a moire pattern perhaps generated by poor contact of the silk screen during the screening of one of the phosphor colors? Seems likely that RCA would sell less than perfect tubes to competitors.

Perhaps the getter above the blue gun was the first one flashed after "pinch off", in a fairly poor vacuum. :scratch2:

Looks like a very fun project.

jr

Totally different ball of wax compared to a CT-100. Difference demod (R-Y and B-Y), but the mixing is done CT-100 style with seperate triodes for RBG in the adder section and a triple diode clamp.

No traditional PLL like the RCA, nor the shock excited crystal approach of the 15 inch GE. Just a color hold control up front. The hue is on the rear panel like on the GE. What were they thinking?

Totally different HV and focus section compared to the RCA. Uses three 3A3s in a doubler arrangement for the ultor and a 1X2? for the focus. According to an old post on the H840CK15 from Folsom, this set has the most stable HV of all the 15 inchers.

Twin 6BG6Gs drive the flyback, compared to the 6CB5s and 6CD6s used in other sets.

The set also makes use of the unusal 6BK5 tube, a minature tube ultimately derived from the 6Y6, 6W6 family. One for audio output (about 2ish watts) and one to drive the delay line.

The audio section in particular leads me to believe this was the brainchild of a Westinghouse engineer and not some copy cat chassis; Westinghouse was one of the only manufacturers using the 6BK5 and 6BN6 combination to lower parts count. I think Zenith may have used it too.

benman94
10-08-2017, 01:59 PM
Impressive! that chassis is a beast! Is the circuitry much different from the CT100, or did Westinghouse not get innovative?

I assume the chassis is copper, like my h22t155, or is that rust?

I have seen drying patterns in some early kasil settled phosphor tubes, but not rings like that... could that be a moire pattern perhaps generated by poor contact of the silk screen during the screening of one of the phosphor colors? Seems likely that RCA would sell less than perfect tubes to competitors.

Perhaps the getter above the blue gun was the first one flashed after "pinch off", in a fairly poor vacuum. :scratch2:

Looks like a very fun project.

jr

The chassis is copper plated.

I couldn't resist the temptation to retest the tube today with the Beltron. Dave Pike will be coming over with his Sencore CR-70 to check for cutoff later this week.

Red:
https://thumb.ibb.co/kL5a1G/20171008_132638.jpg (https://ibb.co/kL5a1G)

Blue:
https://thumb.ibb.co/csNcFb/20171008_132911.jpg (https://ibb.co/csNcFb)

Green:
https://thumb.ibb.co/cwJjvb/20171008_134316.jpg (https://ibb.co/cwJjvb)

I've never seen a tube this closely matched on all three guns, so I'm inclined to think it's gassy, but I got no indication of gas while testing it (blue or purple glow between the cathode and first grid) or with the tesla coil... :saywhat:

I need to find someone in the area with a working 15 inch chassis.

ohohyodafarted
10-08-2017, 02:55 PM
Very curious Ben. :dunno:

Meter readings seem suspicious just like a gassy 15G I have. But the fact that you cant get any neck glow, even with your Tesla coil makes me believe the tube is NOT gassy. I have never seen a gassy tube that failed to give a purple glow with a Tesla coil.

Your getters look just like the ones in my aforementioned 15G (shiny and black) which is gassy, but my tube glows like a neon sign with my Tesla coil.

CR70 cutoff test should prove it one way or the other.

SpaceAge
10-08-2017, 02:59 PM
Any ideas on what causes that weird swirling pattern on some color CRTs? I had a 21CYP22 with the same damn thing. It didn't seem to alter the picture in use, but it looked like hell when the set was off.

Perhaps RCA continued their prewar policy of selling "lesser" CRTs to competitors and holding the best for their own sets.

The 15GP22 in this set was built in the 13th week of '54.

Must be a manufacturing defect, right? I don't see how it could happen afterwards. I thought the imperfect CRTs ended up in test jigs, but was there ever a 15-inch test jig? I'm guessing not.

Good luck, I really hope your picture tube is functional.

benman94
10-08-2017, 03:06 PM
Very curious Ben. :dunno:

Meter readings seem suspicious just like a gassy 15G I have. But the fact that you cant get any neck glow, even with your Tesla coil makes me believe the tube is NOT gassy. I have never seen a gassy tube that failed to give a purple glow with a Tesla coil.

Your getters look just like the ones in my aforementioned 15G (shiny and black) which is gassy, but my tube glows like a neon sign with my Tesla coil.

CR70 cutoff test should prove it one way or the other.

What tesla coil do you use? Any tesla coil of sufficient power should show gas... now I'm going to check and make sure it's working properly with an unused CFL...

old_tv_nut
10-08-2017, 06:28 PM
The fact that you have seen the same sort of swirl on two different tube types that used different methods of application is really interesting. I have never seen anything like this.

In the 70's, Sylvania came up with a brighter phosphor slurry that was thicker than usual. Motorola had trouble using the thicker slurry because of broad swirl marks, but they were faint and only showed up when the tube was lit. Engineering staff were commandeered to take two identical 19 inch sets (except for old and new slurry) home and get unprompted comments from their families to find out if anyone could see the swirls as well as the difference in brightness.

old_tv_nut
10-08-2017, 06:32 PM
Can you hold up something with a contrasty pattern to the tube and see if the reflection is distorted? Wondering if the swirl is a defect in the glass phosphor plate.

benman94
10-08-2017, 06:42 PM
Wayne,

I held a sheet of log paper up to the tube. It was sort of hard to see, given that there was a second reflection from the front of the jug itself, but no, the reflection of the pattern from the inner glass phosphor dot plate was not distorted.

The swirling is definitely the phosphor itself.

dtvmcdonald
10-09-2017, 11:18 AM
About Tesla coils and CRTs. I have a Tesla coil or three. I used them to start discharges
with microwave generators to make Fluorine or Oxygen atoms for my research.
They are exactly like the pictures I see offering the CRT tester ones in ebay.

But ... is using one to test a 15GP22 in a CT-100 (in the set) dangerous to the
parts of the set, like the yoke or purity magnet? I would of course disconnect everything.
The CRT itself is immaterial ... its red gun is truly dead.

benman94
10-09-2017, 11:59 AM
About Tesla coils and CRTs. I have a Tesla coil or three. I used them to start discharges
with microwave generators to make Fluorine or Oxygen atoms for my research.
They are exactly like the pictures I see offering the CRT tester ones in ebay.

But ... is using one to test a 15GP22 in a CT-100 (in the set) dangerous to the
parts of the set, like the yoke or purity magnet? I would of course disconnect everything.
The CRT itself is immaterial ... its red gun is truly dead.

For testing the CRT for gas with a Tesla coil, I removed the purity coil assembly and yoke. On the Westinghouse chassis this is extremely fast. Loosen four nuts, slide everything back and you're done.

I removed them simply because it is easier to see discharge with more of the neck exposed.

I would keep the Tesla coil away from the base as much as possible; check up by the convergence and focusing electrodes. A Tesla coil of sufficient power can burn out a small incandescent light bulb; I imagine a tube heater would be fundamentally no different.

If your tube is gassy, it will be very apparent with the Tesla coil.

Another good test for gas is a Sencore CR-70. Play with bias setting. At sufficiently low bias voltage the meter should peg; the cutoff control fails to control the beam current like normal if the tube is gassy.

Actually, with a sufficiently gassy tube, the voltages from the Sencore are sufficient to strike the gas and cause discharge between the cathode and grids one and two.

See this post for an admittedly poor picture of what I'm talking about:

http://mail.videokarma.org/showpost.php?p=3158010&postcount=16

I would be very curious to know if you can see the faint purple pink glow between the red cathode and first or second grid in your tube Doug.

jr_tech
10-09-2017, 12:23 PM
Gents, is ths what we are talking about here?

https://www.amazon.com/Oudin-Coil-Tesla-Safety-Switch/dp/B009P8CG8M/ref=sr_1_8?ie=UTF8&qid=1408141994&sr=8-8&keywords=tesla+coil

Tis like the one I remember seeing at various CRT production/rebuildng facilities years ago.

not affiliated,
jr

benman94
10-09-2017, 01:13 PM
I have two, one similar to that and a smaller one that operates from a 9 volt battery. Both can fully illuminate a CFL, neither shows any gas on the CRT.

SwizzyMan
10-09-2017, 08:58 PM
Hopefully this isnt too off topic, but it has been intriguing me for awhile now. Is there a reason why the H840 uses RY GY demodulation and the CT-100 uses Q demodulation? Both sets are from the same year and I believe RY GY became standard soon after. Did RCA consider Q demod superior to RY GY?

benman94
10-09-2017, 09:18 PM
Hopefully this isnt too off topic, but it has been intriguing me for awhile now. Is there a reason why the H840 uses RY GY demodulation and the CT-100 uses Q demodulation? Both sets are from the same year and I believe RY GY became standard soon after. Did RCA consider Q demod superior to RY GY?

I/Q demodulation is superior to difference demodulation, yes. (For the record, the Westinghouse is R-Y and B-Y, and it was this that briefly became the preferred demod axes). X and Z demodulation, as explained in Wayne Bretl's response to my query on difference demod in another thread, is essentially just a variant of R-Y B-Y demodulation.

I/Q is more expensive to implement. With R-Y B-Y, you have red and blue essentially ready to go right from the demodators. Just amplify it to drive the grids of the CRT and mix the luma in at the cathodes of the CRT. G-Y can be recovered from a simple network of passive components mixing R-Y and B-Y in the correct proportions. Then amplify it, send it to the grids, and ta-da, you have a color picture.

Note however, that this is not how the Westinghouse accomplished this. The Westy uses triodes to mix the difference signals and the luma, amplifies it, sends the result to a DC clamp, and then the grids are driven with actual R, G, and B.

The RCA method is more complicated. I and Q (or -I and -Q) are recovered from the demodulators. I and Q are then inverted. You now have I, -I, Q, and -Q available. These four signals are mixed in the correct proportions, along with the luma, so as to produce R , G, and B. These signals are then sent to a DC clamp, and the grids are driven with true R, G, and B.

More complicated = more costly. It isn't hard to see why RCA abandon this method of demod for the CTC-4 and all subsequent chassis (during the tube era at least). Difference demod is cheaper. If you want to sell more TV sets, you find a way to make them less expensive.

Now, would the difference between these demod methods actually have been visible on a Westy and a CT-100 both connected to an antenna circa 1954: not no, but hell no.

Watching a 15G is similar to watching TV through a screen door: the dot pattern is plainly visible and all fine detail is essentially obliterated.

On a 21 or 19 inch set, I think the difference may have been visible to very observant viewers under the right set of conditions. Whether those conditions would have existed "in the wild" with an antenna on the roof circa 1954 is again doubtful.

SwizzyMan
10-09-2017, 09:27 PM
Interesting, seems like Q demodulation was just another factor in the poor sales of the CT100.

old_tv_nut
10-10-2017, 01:20 AM
As I probably explained in another thread, the transmitter side Q filters were really not properly specified by the NTSC/FCC. To guarantee good results, Q baseband should have a notch at 900 kHz, so that in the receiver, when the upper sideband is killed by the receiver 4.5 MHz sound trap, the lower Q sideband also has no energy at 900 kHz below chroma and there would be no quadrature distortion, which was the aim of I/Q modulation in the first place. So, when I/Q demodulation was tried on some later sets with larger screens, the quadrature distortion could be quite visible, and results depended on the Q response of the particular color encoder in use at the studio. So, I/Q was a great idea, but suffered from under-specified filter standards. I believe none of the experiments that led to the choice of I/Q actually used an end-to-end system including the RF/IF parts. Later, when the whole system was being tested, there were a million problems to fix, and if the quadrature distortion was visible (say on a large-screen trinescope), it would have been easy to ignore as possibly a small receiver issue that could be fixed later.

Edit: Also, probably posted by me elsewhere, I did an extensive series of tests on I/Q demodulation when I worked for Zenith in the 80s, and even using baseband I/Q with no quadrature distortion, there were some effects that people weren't used to, like the vertical strokes of yellow movie titles turning orangish because the I signal was full amplitude for narrow objects while the Q signal was smeared and reduced in amplitude.

etype2
10-10-2017, 02:54 AM
The last three comments are way over my head.

From a common man’s point of view (average but devoted), it seems to me from recollections and observations back in 1956 and subsequent up to approximately the late 70’s, the “state of the art” in television color broadcasting was incapable of exploiting the potential of the 50’s CRT color reproduction and resolution capabilities.

miniman82
10-10-2017, 08:43 AM
The 15G actually has pretty poor resolution, owing to its diminutive size. Good color yes, but the 19 and 21” sets are where you could really start to get a good color picture at a size you didn’t have to squint at.

benman94
10-10-2017, 02:23 PM
Brought the set up on a Variac today. I figured if I could get the set to produce HV that would definitively say whether the 15G is gassy or not. No HV, and before I had a chance to poke around further a small electrolytic under the main chassis popped.

Electronic M
10-10-2017, 02:54 PM
If I'm not mistaken X Y color demodulation required limiting the bandwidth of the wider band signal in the transmitted I/Q signal. On something like fireworks where there are colored lights of diminishing size the difference between wide and narrow band color might be noticeable in a side by side comparison. Were there viewers that smart, signals that good, two such sets side by side....Perhaps at the FCC hearings prior to NTSC approval and in some TV labs, but unlikely in the real world.

Congrats on the set Ben.

benman94
10-10-2017, 04:49 PM
If I'm not mistaken X Y color demodulation required limiting the bandwidth of the wider band signal in the transmitted I/Q signal. On something like fireworks where there are colored lights of diminishing size the difference between wide and narrow band color might be noticeable in a side by side comparison. Were there viewers that smart, signals that good, two such sets side by side....Perhaps at the FCC hearings prior to NTSC approval and in some TV labs, but unlikely in the real world.

Congrats on the set Ben.

Thanks Tom! :-)

After much thought and deliberation, I've decided the Westinghouse restoration is more than I want to tackle, and admittedly a bit more than I feel I am capable of.

So, Nick Williams will be restoring and aligning the chassis, a fine furniture restoration shop will be completely refinishing the cabinet, my friend Kevin Stankovic will be drawing up model of the mask and knobs in CAD and then reproducing them, and I will simply cooridnate all those efforts and do the final assembly and setup myself.

miniman82
10-10-2017, 09:01 PM
I welcome the challenge.

I have a Halolite on the bench right now, that will be followed by another 621 and a pair of Curtis Mathis color chassis, then I’ll be ready for the westy.

dtvmcdonald
10-10-2017, 10:26 PM
The big problem with I-Q demod is that to get it really right required two
delay lines, one for Y, one for I. And to get them right and the filters with good phase response is not easy ... without digital (or bucket brigades).

My personal opinion is that best is to use any two axes and get the response
quite flat to about 700-800 kHz then rolling off to zero at 1.5 MHz. on both
axes. Few folks notice the resulting bleedthrough from I into Q. Using
equal bandwidths the results are identical independent of the axes used.

However, other people may seriously object to the bleedthrough.

old_tv_nut
10-10-2017, 10:47 PM
My personal opinion is that best is to use any two axes and get the response
quite flat to about 700-800 kHz then rolling off to zero at 1.5 MHz. on both
axes. Few folks notice the resulting bleedthrough from I into Q. Using
equal bandwidths the results are identical independent of the axes used.

However, other people may seriously object to the bleedthrough.

Yep. It was less disconcerting to have the color saturation of details reduced than to have the wrong hue - and if the level of quadrature distortion was low enough, at normal viewing distance in the home it appeared to add some color detail without being obviously wrong. With the engineer's nose to picture tube, the quadrature was visible as a rainbow effect on small strongly colored objects, but it also tended to be hidden by the luminance overshoot due to video peaking.

Since later solid state sets usually simplified the chroma bandpass such that they had this gradual chroma cutoff rather than the classic double-tuned response, it meant that they could actually benefit from composite video input that had double sideband chroma, meaning that the color detail would be somewhat better with a digital source (DVD or digital broadcast converter) fed into the baseband composite input than was possible with RF feed.

reeferman
10-11-2017, 01:14 AM
Interesting, seems like Q demodulation was just another factor in the poor sales of the CT100.

Demodulation had nothing to do with poor sales.
The Consumer Price Index says $1,000 (price of CT-100) in March, 1954 is supposedly equivalent to $9,127 today.

benman94
10-11-2017, 08:43 PM
The big problem with I-Q demod is that to get it really right required two
delay lines, one for Y, one for I. And to get them right and the filters with good phase response is not easy ... without digital (or bucket brigades).

My personal opinion is that best is to use any two axes and get the response
quite flat to about 700-800 kHz then rolling off to zero at 1.5 MHz. on both
axes. Few folks notice the resulting bleedthrough from I into Q. Using
equal bandwidths the results are identical independent of the axes used.

However, other people may seriously object to the bleedthrough.

This raises an interesting question. What exactly is "wide bandwidth" chroma demod? Where does one draw the line in the sand and say this set is narrow band whereas this other set is wide band? I guess it is more accurate to say that some sets are wider or narrower relative to one another...

Take for instance the CTC-2 vs the CTC-5N. Both are "wideband" but the CTC-2 demodulates along I/Q and has extended I response. The CTC-N uses difference demod and starts rolling off at about 600 kHz on both axes, yet both are described as having wide chroma bandwidth on Ed's site. The CTC-2 has wider bandwidth, than the 5, but compared to the CTC-4 they both would qualify as "wide".

miniman82
10-12-2017, 06:36 AM
The actual terms are next to meaningless, but I recall someone telling me it’s actually more correct in most cases to call narrowband circuits ‘equiband’ since most difference circuits have about the same frequency response in both axis. Maybe it was wayne?

benman94
10-12-2017, 12:32 PM
I built a small Tesla coil yesterday using the self-tuning, and extremely efficient, "Slayer" exciter with junk box parts. This morning, I tested it with a 150 watt replacement CFL bulb. Lit up like a Christmas tree.

Retested the neck and face of the 15GP22 for gas with the new Tesla coil. Nadda.

If Dave and I get normal looking cutoff tonight, I'm calling the tube good.

benman94
10-12-2017, 01:13 PM
The ability of the RF from the Tesla coil to excite the gasses in a sealed low pressure tube is inversely proportional the pressure of the gasses inside the tube, over a fairly wide range of pressures. At about 3 torr, the pressure inside of the typical CFL, the Tesla coil was capable of exciting the gasses. Pressures too high will not allow the excitation of the gasses to be visible. On the opposite end of things, a pressure too low won't allow one to observe excitation of the gas from a Tesla coil either.

Once we get below about 10^-3 torr, the excitation of the gasses from the Tesla coil should no longer be visible. A CRT with a pressure above about 10^-4 torr is useless and will start arcing. A tube at 10^-6 to 10^-9 is ideal.

Given what I've observed thus far, I can safely conclude that the tube must be at a pressure no greater than 10^-3 torr. Even a Tesla coil isn't as fool proof as I had thought... Nick is right, the only good test is a working chassis.

old_tv_nut
10-12-2017, 04:15 PM
The actual terms are next to meaningless, but I recall someone telling me it’s actually more correct in most cases to call narrowband circuits ‘equiband’ since most difference circuits have about the same frequency response in both axis. Maybe it was wayne?

Yes, the major difference is non-equiband (I/Q) vs. equiband; a secondary difference is how wide the equiband demods are. Generally, if the demods are "high level" (have high gain and are coupled to the CRT without further amplification) they will have more roll-off due to stray capacitance than a "low level" demod that is followed by an additional stage of amplification (like the RCA X/Z system). The X/Z system was truly a well-optimized trade-off of cost and performance, which was not improved on for many years.

benman94
10-12-2017, 05:18 PM
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
10-12-2017, 07:05 PM
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


:banana: :banana: :banana:

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
10-13-2017, 12:08 AM
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 :deal::D

ohohyodafarted
10-13-2017, 12:15 AM
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
10-13-2017, 12:18 AM
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 :deal::D

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.

benman94
10-13-2017, 12:28 AM
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.

Kevin Kuehn
10-13-2017, 02:03 AM
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. :thmbsp:

benman94
10-13-2017, 10:26 AM
Of course I wasn't really too concerned, just being a smarty pants tonight. :thmbsp:

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.

etype2
10-13-2017, 11:49 AM
Great news about the CRT tests. Hopeing for the best.

benman94
11-04-2017, 06:26 PM
I decided to bring the chassis up on a Variac again to see what if anything I could get. That's when I noticed that the filament of the third 5U4 wasn't glowing. I could have sworn I checked all the 5U4s when I did the first check, but I must have missed one.

Anyway, I inserted a replacement, and was greeted by an angry sounding horizontal section and fireworks show in one of the 3A3s, along with an extremely faint pulsating raster. I replaced it, but not without knocking myself on my ass from the residual HV first, and was greeted by a very bright, stable squished raster.

In the photo, you'll see a slight light blue glow on the inside surface of the neck. I believe this is NOT gas, but rather stray electrons striking the inside of the glass. This is a normal phenomenon, and most beam power tubes and vacuum rectifiers exhibit this, at least when new.

It ain't purty, but it proves that the set is restorable and more importantly, the the 15GP22 has some life in it yet.

Something is FUBAR in the vertical section, but given that I haven't recapped the set yet, this isn't surprising. I'll let Nick deal with it when the chassis gets to Maryland.

Needless to say, I'm ecstatic. :banana: :banana: :banana:

Electrons striking inside of glass?

https://preview.ibb.co/b80KOG/20171104_175205.jpg (https://ibb.co/e5TTHb)

First feeble pulsating raster (bad 3A3):

https://preview.ibb.co/jUrFxb/20171104_173516.jpg (https://ibb.co/c1KPqw)
https://preview.ibb.co/kaxzOG/20171104_175155.jpg (https://ibb.co/hG4eOG)

Much brighter raster with the new 3A3 and healthier HV:

https://preview.ibb.co/k6jkxb/20171104_180539.jpg (https://ibb.co/fLE7Aw)
https://preview.ibb.co/bvtHAw/20171104_180543.jpg (https://ibb.co/mTbFxb)

Zenith26kc20
11-04-2017, 08:27 PM
Yeah baby!
Don't you love seeing that!

Electronic M
11-04-2017, 11:22 PM
Congrats. Not too many of those left making light on the front end...

benman94
11-05-2017, 01:14 PM
Congrats. Not too many of those left making light on the front end...

Thanks! I hope to see your 21-CT-55 lighting up shortly... that's a set I'm truly envious of. Superior wideband chroma demod without the pain in the ass 15GP22 to deal with. That's a winner in my book.

I've determined that I don't have vertical sweep at all, the focus was just messed up. I can now get it sharply focused down to three unconverged lines (not that I'll run it like that). All three guns are fine; using the built in gun killing switches on the back shows normal results.

I've also determined why I don't have vertical deflection; the cathode connection on the 6AH4 is either open, or the tube is stone dead. It doesn't deflect the meter on my Hickok at all, even at 12.6 volts on the filament. I've ordered a new Westinghouse branded 6AH4, and also a 6BL7 for the vertical convergence and color killer. The 6BL7 is very weak. I'll see if that helps. I'd like to be know that the vertical is semi-operational before the set goes to Nick. I'll feel better knowing that all of the major parts are working correctly.

etype2
11-05-2017, 01:43 PM
Patience and you will get there. Good sign on the CRT.

benman94
11-06-2017, 02:13 PM
I am gathering up tubes to send along with the chassis when Nick restores it. The cascode RF amp is listed as either a 6BQ7A or a 6BZ7. I know they're interchangeable, but I'd like to know which should give a better noise factor. I plan on taking the set up to Sault Ste. Marie to DX some Canadian analog repeaters once it's working properly. I just have to see it working the way it would have in 1954 with a proper antenna etc.

The other, more troublesome, tubes are in the chroma. The service manual lists the R-Y and B-Y demod tubes as being either type 6AS6 or 6DB6. It also specifically states to only replace with the type shipped with the reciever. I have no clue what was in the set originally. Am I correct in assuming that one could stick either tube type in, perform an alignment of the chroma sub chassis, and be fine?

Any guidance is much appreciated...

Steve D.
11-06-2017, 02:36 PM
I am gathering up tubes to send along with the chassis when Nick restores it. The cascode RF amp is listed as either a 6BQ7A or a 6BZ7. I know they're interchangeable, but I'd like to know which should give a better noise factor. I plan on taking the set up to Sault Ste. Marie to DX some Canadian analog repeaters once it's working properly. I just have to see it working the way it would have in 1954 with a proper antenna etc.

The other, more troublesome, tubes are in the chroma. The service manual lists the R-Y and B-Y demod tubes as being either type 6AS6 or 6DB6. It also specifically states to only replace with the type shipped with the reciever. I have no clue what was in the set originally. Am I correct in assuming that one could stick either tube type in, perform an alignment of the chroma sub chassis, and be fine?

Any guidance is much appreciated...

Ben,

I assume you've checked the cabinet tube chart if available. And also the Sams which I'm including here. Hope this helps.

-Steve D.

benman94
11-06-2017, 02:41 PM
Ben,

I assume you've checked the cabinet tube chart if available. And also the Sams which I'm including here. Hope this helps.

-Steve D.

The tube chart in the cabinet lists both types unfortunately, with neither scratched out. It also lists 3A3 or 1B3 for the HV rectifiers, but has 1B3 scratched out.

I'll look at the Sam's closer. Thanks Steve.

Steve D.
11-06-2017, 03:07 PM
The tube chart in the cabinet lists both types unfortunately, with neither scratched out. It also lists 3A3 or 1B3 for the HV rectifiers, but has 1B3 scratched out.

I'll look at the Sam's closer. Thanks Steve.

Ben, Sorry. Should have included the Sams top view tube chart. Notice they have the 1B3 & the 6AS6 listed as well as the 6BZ7. Who knows?

-Steve D.

benman94
11-06-2017, 03:30 PM
IIRC, Sam's bought the sets they used for the Photofacts, either that or they were lent them, in any case. I'm going to assume the my set was built with the more common 6AS6, just as the Sam's set apparently had. My set does have 3A3s where the Sam's shows 1B3s... who the hell knows?

I'll try both the 6BZ7 and the 6BQ7A; they are slightly different according to the GE manual, but close enough to assume that either will work.

Electronic M
11-06-2017, 03:43 PM
One quick way to find which tube is better would be to check introduction dates...Often the newer interchangeable type was an improved version of the older one.

benman94
11-06-2017, 06:25 PM
One quick way to find which tube is better would be to check introduction dates...Often the newer interchangeable type was an improved version of the older one.

This was actually a great idea Tom. I looked up the 6BQ7, 6BQ7A, and 6BZ7 intro dates. The 6BQ7 came first with a mu of 35 per section. Then came the 6BZ7 with a mu of 38 and lower noise. RCA promptly retooled the 6BQ7A to match the noise figure of the 6BZ7 and upped the mu of each section to 39. The 6BK7 and 6DJ8 can also sub in parallel heater circuits, both offering an improvement over the 6BZ7/6BQ7A in a cascode arrangement. Then along came the Nuvistor and the rest is history.

old_tv_nut
11-06-2017, 07:07 PM
Regarding 6DB6 vs. 6AS6, since the schematic says either and doesn't show any alternative circuitry, I think it's safe to assume that the only differences are small ones that might skew the alignment a bit, as you said.

benman94
11-09-2017, 11:40 AM
Reminds me of that Beatles tune... "...getting so much better all the time!"

Vertical is back, and the vertical and horizontal dynamic convergence circuits are semi-operational. I may end up starting the recap myself instead of waiting to send it to Nick. It's a good portion of the way there already and I've only replaced a couple of caps.

https://thumb.ibb.co/jHiShb/20171109_110728.jpg (https://ibb.co/jHiShb) https://thumb.ibb.co/m9bPTG/20171109_110745.jpg (https://ibb.co/m9bPTG) https://thumb.ibb.co/bTfwaw/20171109_110808.jpg (https://ibb.co/bTfwaw)

BigDavesTV
11-09-2017, 12:26 PM
"WOW-ZERS!" LOOK AT ALL THE COLOR! Getting better all the time, is right! So enjoy the progress reports, this set is going to display an excellent picture, when all is said and done!

etype2
11-09-2017, 01:22 PM
We second that. Hopeing for the best.

miniman82
11-09-2017, 09:43 PM
As long as you don’t leave me with a mess to clean up, I won’t complain...

benman94
11-10-2017, 02:15 PM
I have six new Westinghouse "Reliatron" 6DB6s and one 6BZ7 on their way to Michigan. I guess that answers the 6AS6/6DB6 and 6BZ7/6BQ7A questions.

benman94
11-12-2017, 11:01 AM
Pulled and cleaned more of the tubes. To my suprise, the set has more than likely spent some time in Canada. There were a couple of Rogers branded tubes, one Marconi branded tube, and one Electrohome tube, all with mid-to-late 1950s datecodes.

The transformer on this thing is massive, as are the filter chokes, and they run very, very cool. 25 Hz chokes perhaps? Given the area it was found in it wouldn't be surprising.

tubesrule
11-12-2017, 12:09 PM
There was a guy, Robert S. outside of Toronto trying to sell a H840CK15 back in 2000. I passed on it at the time and never heard what happened. I know he was trying to sell it for quite some time. Perhaps this is that set?

Darryl

benman94
11-12-2017, 03:33 PM
There was a guy, Robert S. outside of Toronto trying to sell a H840CK15 back in 2000. I passed on it at the time and never heard what happened. I know he was trying to sell it for quite some time. Perhaps this is that set?

Darryl

Dwight found this set in Buffalo, NY, and according to Dwight, the guy he bought it from obtained it from the original owner who used the set to teach color television repair for either a trade school or a Westinghouse program to teach their own techs in house.

I can't imagine the set being the same one that was for sale in the Toronto area, but anything is possible. There was recently (within the past few years) a Westinghouse H840CK15 listed on Toronto Kijiji. I don't recall the set selling, but it was complete and supposedly had a good CRT. Perhaps that was the set from Robert?

EDIT:

My set is most definitely not the set from Robert S. in Ontario. His set had a developmental CRT (the C73599 proto-15GP22) according to Marlin Mackley's site. This set has a production 15GP22 from the 13th week of 1954.

Marlin's site also mentions that the Wingham museum in Ontario has one with a 25 Hz tranny and 25 Hz chokes. Interesting.

benman94
11-15-2017, 12:20 PM
I like to have advertisements for my sets to frame and put near them. I found a number of rather aesthetically pleasing advertisements (Westinghouse ran one hell of a national ad blitz in March of '54), but I also stumbled upon a neat article from January of 1954 showing a Westinghouse H840CK15 prototype and RCA Model 5, as well as articles on Westinghouse color CRT development/manufacturing circa 1954/1955.

Also included is an ad for the lost 19 inch Westinghouse color set, model H890CKU19.

https://preview.ibb.co/kJVJCm/20171115_120354.jpg (https://ibb.co/g4sWXm)
https://preview.ibb.co/fs7yCm/20171115_120535.jpg (https://ibb.co/cJoidR)
https://image.ibb.co/gpDuk6/20171115_120815.jpg (https://ibb.co/kKHbyR)
https://preview.ibb.co/kxu0Q6/20171115_115841.jpg (https://ibb.co/ci4OdR)
https://preview.ibb.co/kzDuk6/20171115_120729.jpg (https://ibb.co/iBBQsm)
https://preview.ibb.co/fO3S56/20171115_120640.jpg (https://ibb.co/eqTuk6)
https://image.ibb.co/gKO5sm/20171115_120909.jpg (https://ibb.co/mpSn56)
https://preview.ibb.co/icK0Q6/20171115_120438.jpg (https://ibb.co/dspOdR)

This last Chicago Tribune ad was used in most major cities, with just the name of the city and the copy about the local dealer switched out.

benman94
11-15-2017, 12:43 PM
The ad for the lost 19 incher:
https://preview.ibb.co/fHBmyR/20171115_123849.jpg (https://ibb.co/naGx56)

Electronic M
11-15-2017, 03:07 PM
The ad for the lost 19 incher:
https://preview.ibb.co/fHBmyR/20171115_123849.jpg (https://ibb.co/naGx56)

I't looks like a 15" set with a bigger CRT installed. If there was anyone with a good spare 19"* CRT and a 15" westy with a lousy mask and dead 15G it would make for an interesting project trying to convert it to be a 19" set.

*(assuming the 19" they were using is the up scaled 15GP22 electronics magazines of the day mentioned)

benman94
11-15-2017, 04:39 PM
I'm quite certain that the jug used was the 19VP22. They mentioned in the dealer sheet for the set that the phosphors were directly deposited on the face of the jug.

I suppose the set could have used the DuMont type 19TP22, which had the CBS style directly deposited phosphors with a 15G style gun. But since the set hasn't turned up, and a DuMont 19TP22 hasn't surfaced, it's all academic.