Purely from curiosity, I removed this CRT from its Mumetal screen: not an easy task, as it was "glued" in at the front corners with what looked like foam.

To my surprise, the front face detached in the process, so I've taken some photos looking back down the tube. I was also surprised to see a "window" through which the electron beam fires: the last object prior to hitting the screen. You can just see where beam has "written" on this window.

The Y-plates are segmented, but all wired in parallel: I did wonder if this was a part common to the 454, and for this latter variant they added inductors to create the delay line?

Photos at

http://www.flickr.com/photos/jaybs/sets/72157630205984812/

John

On the 7834 where I have separated the shield from the CRT a couple of
times, they are completely separate pieces. There it is possible to
install the CRT without the shield although all of the magnetic
interference from the rest of the oscilloscope renders the CRT useless
until the shield is installed; the display becomes a smear.

On Thu, 20 Jun 2013 16:01:06 -0000, "John S" <John@...>
wrote:

Purely from curiosity, I removed this CRT from its Mumetal screen: not an easy task, as it was "glued" in at the front corners with what looked like foam.

To my surprise, the front face detached in the process, so I've taken some photos looking back down the tube. I was also surprised to see a "window" through which the electron beam fires: the last object prior to hitting the screen. You can just see where beam has "written" on this window.

The Y-plates are segmented, but all wired in parallel: I did wonder if this was a part common to the 454, and for this latter variant they added inductors to create the delay line?

Photos at

http://www.flickr.com/photos/jaybs/sets/72157630205984812/

John

I'd say it has suffered some damage, and may not work properly any more. Ed

Ed Breya wrote:

I'd say it has suffered some damage, and may not work properly any more. Ed

He definitely defaced it.

"Michael A. Terrell" <mike.terrell@...> wrote:

He definitely defaced it.

Groan! Seriously, those corners are not intentionally glued.
They do stick pretty badly sometimes. The proper way to get the
tube out is to loosen the clamp around the neck (inside the shield)
and push like crazy on the center of the base with your thumbs.
Have a soft landing zone ready for when it pops out. No shocks and
no prying. That's bad mojo.
-ls-

"those corners are not intentionally glued"

Oh yes they were! Brown fine-pored foam, just in the four corners. It wasn't going to pop out with mere mortal efffort.

John

--- In TekScopes@..., "Ed Breya" <edbreya@...> wrote:

I'd say it has suffered some damage, and may not work properly any more. Ed

Ed:

Much as it grieves me, I have to concur. ;-(

--- In TekScopes@..., "John S" <John@...> wrote:

"those corners are not intentionally glued"

Oh yes they were! Brown fine-pored foam, just in the four corners. It wasn't going to pop out with mere mortal efffort.

John

I respectfully disagree. The corners were not intentionally glued. Read the "CRT replacement" section in the service manual.

The latex foam used as a cushion deteriorates over time. In the process, all exposed external surfaces become "sticky" and act just like the pressure sensitive adhesive that was applied to just one side (the shield side) when the cushions were installed in the shield. Over the course of four or five decades, all surfaces of the deteriorating foam adhere to anything touching them, including the CRT.

- Steve

larrys@... wrote:

"Michael A. Terrell" <mike.terrell@... <mailto:mike.terrell%40earthlink.net>> wrote:

He definitely defaced it.

Groan! Seriously, those corners are not intentionally glued.
They do stick pretty badly sometimes. The proper way to get the
tube out is to loosen the clamp around the neck (inside the shield)
and push like crazy on the center of the base with your thumbs.
Have a soft landing zone ready for when it pops out. No shocks and
no prying. That's bad mojo.

A bad pun is a terrible thing to waste. ;-)