Stromberg Carlson X-21 M4B project.

[Yamamaya42]

Originally Posted by Electronic M

Well you all could come to Wisconsin to cool off in the severe thunderstorms we've been getting the last couple of days... The dime sized rain drops are refreshing till the thunder scares you inside. I make it sound so appealing don't I?

Oh, we also get pretty bad thunderstorms here too, lots of huge rain, wind, hail... Hail hail fire and snow, call the angel, we will go...
Wait a sec, lets NOT go there!
Anyway, thunderstorms, tornadoes, etc...
Which leads to another strange tale, my parents place has ( still does ) a primitive intercom system in it, all transistorized, with the electronics being in the main unit, and the remotes being nothing but a speaker, switches and pots.

One night there was a rather bad thunderstorm, as I was trying to sleep, ( or as I was almost asleep), there was a deafeningly loud KOBOOM and bright flash outside the widow, ( my window and my parents faced front), it was soon found out that struck the oak tree out front.
It felt like I jumped 3 feet above my bed when it hit...

It was quickly seen that not only was the tree hit, but the bolt had forked, and blasted through the roof and hit some metal molding that ran between the wood boards above the awning over the entryway and found it's way to a light fixture, all the edges were burned.
Afterward, it was found that the intercom control unit had been burned out and had to be replaced, but after it was, the 2 forward facing remote units still did not work right, this made no sense, for there was no semiconductors in them, so how could they be affected?
After they too were replaced and the entire system working again, it was soon discovered what happened to the remote units, the strike had somehow disrupted the permanent magnets in the speakers leaving them too weak to be of use anymore.
Something to this day that still boggles the mind.

Shortly after that happened, my parents had lightning rods added to the house, and there was never a problem with strikes again.

[Electronic M]

Lol.

Back when I lived in Florida the family home had been through something similar before we bought it. Supposedly it had taken a lightning strike and the ground floor AC was taken out (it's junction box and a number of outlets were rather sooted up). We had this late 70s Nutone intercom system that was dead (don't know if it was the lightning or what) but the early digital LED clock still worked (albeit it wouldn't allow setting time). I was a teen then and just getting the hang of tube stuff but not familiar with SS so I left the intercom be.

[Yamamaya42]

what I find amusing is, this thing has 23 tubes, and the RCA 630TS / FADA has 30.

[Yamamaya42]

Originally Posted by Electronic M

Just knock the loose stuff off, mask the areas that shouldn't have dag and spray some Slip Plate on it. That will fix the bald spots long term.

would something like film tape work also?
like i am using here?
https://imgur.com/xOxAbso

[Electronic M]

Originally Posted by Yamamaya42

would something like film tape work also?
like i am using here?
https://imgur.com/xOxAbso

Unless the glue in the tape is conductive, NO it's not a substitute. Slip Plate is fairly affordable and is essentially aquadag spray paint. If you want to continue restoring sets this $18 can will respray many CRTs for future projects. https://www.amazon.com/Slip-Plate-Pl.../dp/B005ESITFQ I got 3 roundy CRTs and 2-5 black and white tubes out of my last can....I'd have gotten more out but the mixing ball was a glass marble and it eventually chipped up and the chips clogged the spray valve...I ended up carefully venting the remainder of the can into a bottle where it dried on me before I could use it all...I need to order another can one of these days.

Many sets especially those with doorknob HV caps don't need all their dag....But the dag has to be grounded, and every bit of dag has to be electrically connected to every other bit or arcing will occur between day islands. This arcing creates electrical interference, HV ripple and if strong and sustained can locally heat the CRT glass and cause implosion in some extreme cases.

In a pinch Blaster graphite spray lube from the hardware store can work but it's resistance is a bit too high for the application....it's basically watered down slip Plate.

[Yamamaya42]

Is it me, or does it seem that the GE 21AUP4A in the Stromberg Carlson x-21 was made rather thin compared to other tubes of its size? :O

[Yamamaya42]

hauled the SC chassis upstairs to take a look at it, and noticed as i mentioned before, it has been worked on before at least once if not more.

I also saw this right away.

https://imgur.com/Ob83Mxm

burned resistor

it SHOULD BE100 ohms...
https://imgur.com/xAm1uzk

it checked at 187 ohms.
the cap with it is way bad too, should be 5mfd checks at 210 pf.


that being on the HOT cathode, I have doubts this TV was working very well at all like this when it was put in storage.

I will no doubt find many other crappy caps all over the set, and it's too risky to power up in this state as of now.

[Yamamaya42]

As i showed before, C1 in this set has been replaced before, but that does not mean that it is still good

most likely is, but who knows

https://imgur.com/fCAigeF

right now, i have it isolated from everything else and am powering up on a variac to 300 v for a while.
the cap is rated at 450v

[Jeffhs]

Originally Posted by init4fun

While the rest of the country tends to think of the northeast as being always cold , every so often even here the heat vents of Hell open up and we roast pretty much like the rest of ya . Only difference is on average we get maybe 20 or so days of this each Summer , VS the southern states that roast pretty much all Summer long .

I live in northeastern Ohio, 30 miles east of Cleveland, which often gets very hot weather this time of year. This summer has been very hot and humid here so far, with temperatures in the 80s and lower 90s; fortunately, I live in an apartment building with central air, so the heat doesn't bother me as long as I don't go outside during the day for any length of time. If I have things to do outside my apartment (taking out trash, etc.) I always wait until at least seven or eight o'clock or so, when the heat is not nearly as bad.

I like summertime, as it is my favorite time of year (I was born in the middle of the summer of 1956, which has a lot to do with it), but gee whiz, this beastly hot weather we've been seeing here this summer is too much. I guess I should enjoy it while I can, though, because it won't be long before it gets colder than the proverbial iceberg and the snow starts. This region can and does get some bad snowstorms (how can I ever forget the Blizzard of 1978, in which the entire Cleveland area and other parts of the country were snowed in for days or weeks), but not nearly as bad as Buffalo and Syracuse, New York, so I guess I should count my blessings.

Oh well, that's life in the Great Lakes region of this country, like it or not. I've been here all my life and am used to it by now. Goodness knows I don't like it, but that's the way our weather is in the winter.

[Yamamaya42]

FAILED!
https://imgur.com/nCuesm2
after 10-15 min the cap was 115f-120f not going to trust it!

[Jeffhs]

Originally Posted by Yamamaya42

FAILED!
https://imgur.com/nCuesm2
after 10-15 min the cap was 115f-120f not going to trust it!

I hope you get that SC TV working again. Those were good sets. My aunt, now deceased, had a Stromberg-Carlson TV in a white console cabinet with doors and Chinese style door pulls (the thing weighed the proverbial ton, as do all consoles; in fact, the picture of your own SC console reminded me of it), which was, I believe, the first TV she and her husband had. I don't know how long that SC TV lasted for them (I think it may have gone until the mid-1960s), but when it finally died it was replaced by a metal-cased RCA Victor 17-inch portable.


The RCA portable lasted some time (don't recall how long) and was replaced by a Westinghouse instant-on (!) color console. By then (after she divorced her husband), my aunt had moved to a Cleveland suburb that was in a very strong signal area, so her new Westinghouse color TV could receive all six Cleveland TV stations in color (the picture looked great, as I recall), without an antenna (the first "antenna" she used on that set was a piece of wire). Eventually, however, she got a Spico all-channel rabbit-ear TV antenna which she wouldn't have needed in that area, as strong as the TV signals from the local stations were. She eventually moved to an eastern Cleveland suburb, but kept the Westinghouse TV and its rabbit-ear antenna.

The rest is history.

[Yamamaya42]

I'm a bit disappointed the cap is bad, but not surprised, seeing as the set was kept in a damp environment for such a long time that the cabinet is warped, and will most likely be harder to fix than the electronics.
No telling when in the past that cap was replaced, but it should not be uncomfortably warm to the touch after being powered up for just such a short time, oh well, just one more electrolytic capacitor to replace, IE all of them...

[Yamamaya42]

OK... this is a bit confusing
the 21aup4a has an aluminized screen and an ion trap?

I thought ones with aluminized screens did not need traps.

or is this just an odd tube?

[mrjukebox160]

https://frank.pocnet.net/sheets/093/2/21AUP4B.pdf

[Yamamaya42]

snip/ paste from another froum
>The Ion trap was used to prevent “ion burn” to the screen.. It is impossible to remove every molecule of gas from the tube. The electron beam strikes molecules of gas, knocking off an electron thus creating an ion. These ions would travel to the screen and damage it causing “ion burn” which showed up as a dark patch in the middle of the screen. Eventually aluminized tubes solved this problem completely. But before aluminized tubes were invented the combination of a “bent gun” and an ion trap protected the screen. The bent gun was actually pointed at an angle so the electrons would have struck the neck of the tube somewhere. But the magnetic ion trap was used to bend the electron beam so that it would hit the screen. Those nasty ions, being heavier than electrons were deflected by the magnet of the ion trap, differently than the electrons so they did not hit the screen. In an aluminized tube, a thin coating of aluminum is deposited over the rear surface of the screen. The Aluminum also covers the whole inside surface of the tube. It does at least 4 important things. <P>(1) It protects the screen from ions, thus eliminating the need for the bent gun and ion trap.<BR>(2) It reflects the light emanating the rear surface of the phosphor screen to the front thus almost doubling the brightness.<BR>(3) It prevents scattering of the light inside the tube thus improving contrast.<BR>(4) It acts as one plate of a high voltage capacitor. The other plate is the conductive outside paint or “aquadag”. This capacitor filters the high voltage. Which is derived from the horizontal oscillator and has 15 kHz ripple.

thus my confusion with this tube