Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Early Color Television

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 01-19-2018, 12:22 PM
WISCOJIM WISCOJIM is offline
VideoKarma Member
 
Join Date: Sep 2005
Location: Grand Chute, Wisconsin
Posts: 1,929
Cataract repairs - are we missing the safety glass aspect?

I've seen plenty of threads where people "fix" a cataract, and I have also done many myself in the past. But I always had this feeling that the way we are sealing these jugs is all wrong.

Does anyone really believe that taping or caulking really makes the CRT front "safety glass"? If you think sealing only the edges of the now cataract free CRT gives you any real protection, you are fooling yourself. Why do you think that inner layer was put in there for in the first place? No, not just to keep dust out...

Real safety glass requires that the inner layer holds the front and back glass together, just like in automotive windshields. Removing that layer just gives you two pieces of glass with an air gap.

Has anyone tried doing it the correct way using a resin between the CRT and the "cover glass"? If so, please share details.

I think we all should reconsider how we remove cataracts, and come up with a way to put the "safety" factor back in.

.
Reply With Quote
  #2  
Old 01-19-2018, 12:46 PM
Kamakiri's Avatar
Kamakiri Kamakiri is offline
Administrator
 
Join Date: Jun 2002
Location: Buffalo, New York
Posts: 5,055
I'm all for it....if there's a way.
__________________
"Restoring a tube TV is like going to war. A color one is like a land war in Asia."
Reply With Quote
  #3  
Old 01-19-2018, 01:08 PM
ohohyodafarted's Avatar
ohohyodafarted ohohyodafarted is offline
Bob Galanter
 
Join Date: Sep 2005
Location: Whitefish Bay, Wi (Milwaukee)
Posts: 970
You are correct. Little protection is given by taping the safety glass to the crt.

That said, as hobbyists, we do not have the materials or equipment to do this kind of rework.

Even at Hawkeye, a fairly large crt rebuilder, the safety glass was fastened in place with a bead of silicone sealant and carton sealing tape around the circumference. If Hawkeye didn't have the resources to bond the safety glass, then I think it unreasonable to think we can do it.
__________________
Vacuum tubes are used in Wisconsin to help heat your house.

New Web Site under developement
ME http://AntiqueTvGuy.com
Reply With Quote
  #4  
Old 01-19-2018, 01:04 PM
Tom9589 Tom9589 is offline
VideoKarma Member
 
Join Date: Jan 2013
Posts: 152
I fully understand the principle behind automotive safety plate glass. Why did we go for so long with a separate safety glass with a huge air gap between the glass and the CRT? Also consider CRTs with no safety glass, just a band around the tube under tension. All you want is that the safety glass stop the CRT glass from being projected outward toward the viewer, not hold it in place like a windshield.
Reply With Quote
  #5  
Old 01-19-2018, 01:54 PM
WISCOJIM WISCOJIM is offline
VideoKarma Member
 
Join Date: Sep 2005
Location: Grand Chute, Wisconsin
Posts: 1,929
Quote:
Originally Posted by Tom9589 View Post
I fully understand the principle behind automotive safety plate glass. Why did we go for so long with a separate safety glass with a huge air gap between the glass and the CRT?
Don't mistake plate glass for actual safety glass. I know that a lot of the 1950's TVs I junked in the past did have actual safety glass (with the internal bonding agent) in front of the CRT. And that safety glass was between the CRT and the viewer.

Quote:
Originally Posted by Tom9589 View Post
Also consider CRTs with no safety glass, just a band around the tube under tension.
I'm assuming in the case of those CRTs there were improvements in the glass to bring up the safety margin.

Quote:
Originally Posted by Tom9589 View Post
All you want is that the safety glass stop the CRT glass from being projected outward toward the viewer, not hold it in place like a windshield.
With the force of an implosion, a sheet of glass offers little actual protection to keep the front glass from shattering and sending its own shards everywhere.

I would imagine in every instance where a CRT was designed with the resin layer, it was there for a specific safety reason. Otherwise they would have come with just an edge bonding in the first place.

.
Reply With Quote
Audiokarma
  #6  
Old 01-20-2018, 12:54 AM
reeferman's Avatar
reeferman reeferman is offline
VideoKarma Member
 
Join Date: Jun 2004
Location: St. Louis
Posts: 510
Life was simpler then.

[QUOTE=Tom9589;3195034]I fully understand the principle behind automotive safety plate glass. Why did we go for so long with a separate safety glass with a huge air gap between the glass and the CRT?


We had a 21FB set with come in with a BB hole in it that went through both the safety glass and the CRT face glass. Just left a hole the size of the BB. We couldn't believe it. A one in a million shot, kid.

BTW, there was no "huge air gap".

Last edited by reeferman; 01-20-2018 at 12:59 AM.
Reply With Quote
  #7  
Old 01-20-2018, 02:17 AM
MadMan's Avatar
MadMan MadMan is offline
'A Disgusting Brony'
 
Join Date: Oct 2016
Location: Chicago
Posts: 642
Quote:
Originally Posted by reeferman View Post
We had a 21FB set with come in with a BB hole in it that went through both the safety glass and the CRT face glass. Just left a hole the size of the BB. We couldn't believe it. A one in a million shot, kid.
Must've been one hell of a bb gun. You sure the kid wasn't playing with his dad's .22?
Reply With Quote
  #8  
Old 01-20-2018, 08:04 PM
reeferman's Avatar
reeferman reeferman is offline
VideoKarma Member
 
Join Date: Jun 2004
Location: St. Louis
Posts: 510
Quote:
Originally Posted by MadMan View Post
Must've been one hell of a bb gun. You sure the kid wasn't playing with his dad's .22?
It was a BB gun.
Reply With Quote
  #9  
Old 01-20-2018, 07:53 AM
WISCOJIM WISCOJIM is offline
VideoKarma Member
 
Join Date: Sep 2005
Location: Grand Chute, Wisconsin
Posts: 1,929
Quote:
Originally Posted by reeferman View Post
BTW, there was no "huge air gap".
I assumed Tom was talking about those sets that have the CRT about 1-1/2 to 2 inches behind the flush mounted glass on many of the old TVs.



.
Attached Images
File Type: jpg lk.jpg (30.2 KB, 136 views)
Reply With Quote
  #10  
Old 01-19-2018, 02:00 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 4,686
There were both glass scatter tests and specifications and impact tests/specs over the years, I don't think we can definitively say that the resin bonding was intended specifically to limit scattering, or only to meet the impact tests. If there is someone around who has access to the historical development of UL tests, or very unlikely, some manufacturer's documents (boy, would they not want that to be public), I think we can't say. The resin bond MAY have been mainly for dust exclusion, while the glass continued to provide the same protection as when it was air-spaced.

Can someone who has witnessed breaking a resin tube tell us if it captured all fragments like a windshield, or did glass pieces spray?

If the latter, then the resin may have reduced the force/distance of the spray, or may not. Actual test results with/without resin would be needed to answer this.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
Audiokarma
  #11  
Old 01-19-2018, 02:56 PM
TUD1's Avatar
TUD1 TUD1 is offline
TheUniversalDave1
 
Join Date: Jan 2014
Location: Birmingham, AL
Posts: 1,573
I've done several cataracts and I don't really worry about implosion all that much. I once did a cataract removal on the bathroom floor in my pajamas. A few months ago, I needed to bust up an old dead Zenith 25GP22, and even with a good sized sledgehammer, it took a lot of force to get it to pop.
__________________
"If you wish to make an apple pie from scratch, you must first invent the universe." -Carl Sagan
Reply With Quote
  #12  
Old 01-19-2018, 07:07 PM
madlabs madlabs is offline
VideoKarma Member
 
Join Date: Jul 2016
Posts: 271
Quote:
Originally Posted by TUD1 View Post
I've done several cataracts and I don't really worry about implosion all that much. I once did a cataract removal on the bathroom floor in my pajamas. A few months ago, I needed to bust up an old dead Zenith 25GP22, and even with a good sized sledgehammer, it took a lot of force to get it to pop.
Worry? No. Take sensible and reasonable precautions? Hell yes! I've never done a cataract removal but have popped a few CRT's in my youth (back in the early 7's we didn't know better!) and they can really throw some glass sometimes. A piece in the eye would really ruin your day. I'd be wearing a face shield, some gloves and a jacket. Maybe it goes back to my firefighter days, we did crazy stuff but with proper gear.

What about the air gap between a Predicta CRT and the plastic safety screen?
Reply With Quote
  #13  
Old 01-19-2018, 07:25 PM
TUD1's Avatar
TUD1 TUD1 is offline
TheUniversalDave1
 
Join Date: Jan 2014
Location: Birmingham, AL
Posts: 1,573
A piece of glass in an eye? Meh. I've got two of 'em.
__________________
"If you wish to make an apple pie from scratch, you must first invent the universe." -Carl Sagan

Last edited by TUD1; 01-19-2018 at 11:46 PM.
Reply With Quote
  #14  
Old 01-19-2018, 11:17 PM
MadMan's Avatar
MadMan MadMan is offline
'A Disgusting Brony'
 
Join Date: Oct 2016
Location: Chicago
Posts: 642
I've said this before, just buy a shitload of UV-activated LOCA glue. It's the stuff they use to glue cell phone's glass to the screen. Kind of expensive for that much, but hey, that's the price of 'safety.'

Game is hard.

Also, while I agree that the mushy stuff between the CRT and the safety glass does definitely add some protection... I'm pretty sure that if the tube wanted to implode, anybody in the vicinity would have a really bad day, whether or not it had the mushy stuff.
Reply With Quote
  #15  
Old 01-19-2018, 11:24 PM
WISCOJIM WISCOJIM is offline
VideoKarma Member
 
Join Date: Sep 2005
Location: Grand Chute, Wisconsin
Posts: 1,929
Quote:
Originally Posted by MadMan View Post
Also, while I agree that the mushy stuff between the CRT and the safety glass does definitely add some protection... I'm pretty sure that if the tube wanted to implode, anybody in the vicinity would have a really bad day, whether or not it had the mushy stuff.
And I'm sure it would have given more protection when the tubes were fresh, and not with 50+ year-old crusty mushy stuff like we see nowadays.

.
Reply With Quote
Audiokarma
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:25 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
ęCopyright 2012 VideoKarma.org, All rights reserved.