EEVblog Electronics Community Forum

General => General Technical Chat => Topic started by: Homer J Simpson on August 21, 2016, 02:25:41 am

Title: Vintage CRT Safety Lense Removal and Cleaning
Post by: Homer J Simpson on August 21, 2016, 02:25:41 am

https://www.youtube.com/watch?v=32_qMSWEdjc (https://www.youtube.com/watch?v=32_qMSWEdjc)

Title: Re: Vintage CRT Safety Lense Removal and Cleaning
Post by: Brumby on August 21, 2016, 03:10:56 am

Never knew that about early TVs.

I remember our first TV (B&W).  It had a flat glass plate at the front of the cabinet, with the CRT sitting behind it.  No bonding and nothing between them but air.


I did have a laugh at his procedure for removing the degaussing coil from a donor set.

Title: Re: Vintage CRT Safety Lense Removal and Cleaning
Post by: helius on August 21, 2016, 06:11:11 am

PVA glue was also used to bond the front glass onto the CRT of many 1970s computers and "glass TTY" terminals. It looks really wacky when it breaks down:

(http://www.retrotechnology.com/restore/nick_adm_CRT.jpg)
This is not mold! It's decayed poly-vinylalcohol.

Title: Re: Vintage CRT Safety Lense Removal and Cleaning
Post by: N2IXK on August 21, 2016, 06:47:14 pm

I worry about the long-term safety of a CRT that has had this procedure done.

The entire purpose of the bonded faceplate is for implosion protection.  Removing the resin layer eliminates this safety feature, even if the glass faceplate is reinstalled over the tube.  Before the bonded faceplates were introduced, a separate safety glass panel was used in front of the CRT.  The removed and reinstalled faceplate is NOT made from safety glass, and, without the resin bonding layer, offers little more than added shrapnel in the event of a screen implosion.

Some vintage TV collectors have had the tube implode while attempting this "cataract surgery", as well.