View Full Version : Predicta - Tube type 21SFA - dangerous?


madlabs
11-26-2016, 11:44 AM
Hi All,

I'm assessing the two Predictas I just picked up. On the inside of the cabinet of one of them it has a sticker which reads:

CAUTION TO USER
The picture tube type 21SFA is dangerous to handle. Refer all servicing and replacement to Philco qualified personnel only.

What's up with that? This one also has the sticker for having the 21EAP4 replaced with a 21FDPA.

Thanks!

Phil Nelson
11-26-2016, 12:20 PM
Sounds like a standard CRT warning label, similar to this one:

http://antiqueradio.org/art/Hoffman7M112CRTLabel.jpg

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

mstaton
11-26-2016, 12:21 PM
All CRT's can be dangerous.(They all have the same warning sticker) They are under very high vacuum. Be extremely carefull especially around the neck where the glass is at it's thinest. wear eye protection.

benman94
11-26-2016, 01:04 PM
I just had my first CRT implosion the other day. Definitely treat any CRT with kid gloves.
I had a bad 12LP4 that I pulled from a Philco or Hallicrafters or some damn thing. Anyway, I've been boxing up CRTs to ship to Europe for my stay overseas. I set the bad 12LP4 on the lower rear patio, went upstairs to get the mail. I met my terrified Dachshunds on the stairs, and discovered broken glass all over the back yard, all over the patio, and shards of glass imbedded in the wooden deck above the patio. The doorwall was (surprisingly) unscathed.
Bottom line: be careful.

decojoe67
11-26-2016, 01:35 PM
After installing a CRT in an Admiral 7" one time it imploding on me with only a loud crack and hiss. I was told I was lucky. It could've been a lot worse. They are delicate at the neck and can be easily ruined if mishandled.

Titan1a
11-26-2016, 08:20 PM
Been there. Done it twice. Just call me a big dummy! Hasn't occurred since.

Eric H
11-26-2016, 09:49 PM
I just had my first CRT implosion the other day. Definitely treat any CRT with kid gloves.

So what do you think caused this? Temperature difference? did the Dog knock it off the patio? They almost never just implode spontaneously.

benman94
11-26-2016, 10:06 PM
The Dachshunds were inside, so it couldn't have been them. Temperature drop too rapidly was the most likely cause. It had been on a tester, cooking at 9 volts, so the neck was very hot. I took it right outside, where the temp couldn't have been more than 40, and was likely closer to freezing. Now that I think of it, scratching the face when I set it on the pavement could have contributed greatly as well. All I know for sure is that I'm never putting duds on the back patio again. I'll walk them right out to the curb on trash night from here on out.

Eric H
11-26-2016, 11:29 PM
Well if you do put one out again set up a Go Pro to capture it. :D

I always either break the nipple or punch a tiny hole through the Anode connector to let the atmosphere in.

David Roper
11-27-2016, 03:38 AM
scratching the face when I set it on the pavement

This. A breach in the neck rarely results in implosion, but a nick to the face has always been considered an implosion waiting to happen. Sometimes the wait isn't long. I remember a question to TV Guide's regular tech Q&A column about what to do about a TV screen nicked by a kid's thrown toy. The reader was advised to carefully--carefully--unplug the TV, turn it toward the wall, then run (not walk) to the nearest repair shop.

Safety glass serves a dual purpose.

madlabs
11-27-2016, 12:09 PM
OK, so just a standard warning. I was thrown because it seemed to be specific to the tube 21SFA. Which doesn't cross to a CRT that I could find. I will continue to be careful!

Thanks!

Kevin Kuehn
11-27-2016, 12:24 PM
I remember a question to TV Guide's regular tech Q&A column about what to do about a TV screen nicked by a kid's thrown toy. The reader was advised to carefully--carefully--unplug the TV, turn it toward the wall, then run (not walk) to the nearest repair shop.

Safety glass serves a dual purpose.

I'm surprised they didn't suggest first throwing a heavy blanket(maybe a couple) over the set. In the above case I would think it would have been the safety glass that was nicked. But always better to be safe than sorry. What's scary is that many of us collectors likely have a couple crt's hanging around with scratched faces. :scratch2:

kvflyer
11-27-2016, 02:47 PM
...
What's scary is that many of us collectors likely have a couple crt's hanging around with scratched faces. :scratch2:

I would be one of those collectors. I have a color RCA CTC-9 "roundie" and a B/W Zenith 12" Porthole with CRTs which test NOS. I just have to get off of my fat arse and restore them. :tears:

StellarTV
11-27-2016, 03:06 PM
SF-21 was just Philco's proprietary part number for their home-grown narrow profile CRT. 21EAP4 was based on the industry standard numbering scheme.

SF stood for Sure Failure.